Biotic and abiotic factors affecting calling activity at ...

Biotic and abiotic factors affecting calling activity at traditional breeding ponds of Puerto Rican crested toads (Bufo [Peltophryne] lemur) in Quebradillas, Puerto Rico by Gail Susana Ross A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCES in BIOLOGY UNIVERSITY OF PUERTO RICO MAYAGÜEZ CAMPUS 2007 Approved by: ________________________________ Allen R. Lewis, Ph.D. Member, Graduate Committee

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________________________________ Carlos J. Santos, Ph.D. Member, Graduate Committee

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________________________________ Alberto R. Puente Rolón, M.Sc. Member, Graduate Committee

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________________________________ Fernando J. Bird-Picó, Ph.D. President, Graduate Committee ________________________________ José A. Cruz-Burgos, Ph.D. Representative of Graduate Studies ________________________________ Lucy Bunkley-Williams, Ph.D. Chairperson of the Department

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ACKNOWLEDGEMENTS Many people and organizations contributed to the development of my research. It would have been impossible to carry out this work without their support. Let me begin by thanking Bob Johnson, Andrew Lentini and Sarah Ingwersen at the Toronto Zoo for introducing me to the Puerto Rican crested toad. In Puerto Rico, staff at the US Fish and Wildlife Service Caribbean field office set me up and running, a special thanks to Silmarie Padrón and Carlos Pacheco. Alberto R. Puente Rolón, Sondra Vega Castillo, José A. Cruz-Burgos, Marisel López and José Sustache from Iniciativa Herpetológica, Inc. offered technical support, guidance and encouragement. I wish to thank them for their support and the bottomless energy with which they strive to educate the public on the importance of herpetology. At the University of Puerto Rico, thanks to Fernando Bird-Picó for encouraging me to continue my studies. I am grateful to Raul Machiavelli, Allen Lewis, Juan Carlos Benavides and Robert Smith for their help in statistical analyses and to Amos Winter for helping me unravel weather data. Marcela Bernal and Roseanne Medina worked for hours on GIS habitat modeling, and Ricardo Colón collected and identified invertebrates with the help of Carlos Santos. A special thanks to Jenny Urbina for being in the right place at the right time to assist in analyzing hours of frog calls, as well as William Rivera and Natalia Falcón Banch. The Biology Department supplied a teaching assistantship, access to field vehicles and a building full of enthusiastic and helpful staff. The WALSAIP project (Department of Electrical and Computer Engineering) provided a research assistantship to cover my last semester. Thanks to Juan G. González Lagoa and the Resource Center for Science and Engineering for funding my ii

travel to the SCGIS conference in California, where SCGIS and ESRI provided GIS training and ArcGIS programs. At UPR Río Piedras, I would like to thank Luis Villanueva for guidance with equipment and Alonso Ramírez for also identifying invertebrates. In the field, I am indebted to Ernesto Estremera, Marcos Caraballo, Papo Vives and the García family for their support and assistance. In particular I would like to thank Willie Hernández for his invaluable field support, companionship and for pulling me out of pond 3. A special thanks to all my friends here for providing music and laughter and to those abroad for keeping me in their lives, despite the length of time between phone calls and visits. Above all, I thank my family, for laughing with me in my quest to find this elusive toad. Funding was provided by cooperative agreement # 1448-40181-04J012 between US Fish and Wildlife Service and Iniciativa Herpetológica, Inc.

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TABLE OF CONTENTS THESIS TITLE ............................................................................................................................ I ACKNOWLEDGEMENTS .......................................................................................................II TABLE OF CONTENTS .......................................................................................................... IV LIST OF TABLES ..................................................................................................................... VI LIST OF FIGURES ................................................................................................................. VII CHAPTER 1- DESCRIPTION OF LANDSCAPE AND SPECIES PRESENCE AT PUERTO RICAN CRESTED TOAD (BUFO [PELTOPHRYNE] LEMUR) NORTHERN BREEDING PONDS.................................................................................................................................................10 ABSTRACT ................................................................................................................................11 RESUMEN ..................................................................................................................................12 INTRODUCTION .....................................................................................................................13 MATERIALS AND METHODS .............................................................................................15 RESULTS ....................................................................................................................................21 DISCUSSION ............................................................................................................................23 RECOMMENDATIONS ..........................................................................................................30 LITERATURE CITED ...............................................................................................................32 TABLES .......................................................................................................................................34 FIGURES.....................................................................................................................................34 APPENDIX A .............................................................................................................................43 APPENDIX B..............................................................................................................................46

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CHAPTER 2 - EFFECT OF ABIOTIC VARIABLES ON THE CALLING ACTIVITY OF AMPHIBIANS AT BUFO [PELTOPHRYNE] LEMUR NORTHERN BREEDING SITES ....48 ABSTRACT ................................................................................................................................49 RESUMEN ..................................................................................................................................50 INTRODUCTION .....................................................................................................................51 MATERIALS AND METHODS .............................................................................................53 RESULTS ....................................................................................................................................56 DISCUSSION ............................................................................................................................61 LITERATURE CITED ...............................................................................................................70 TABLES .......................................................................................................................................73 FIGURES.....................................................................................................................................76 APPENDIX A .............................................................................................................................88 APPENDIX B..............................................................................................................................91

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List of Tables

Tables

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Chapter 1 Table 1. General characteristics of five ponds under investigation.

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Chapter 2 Table 1. List of rain events, total recordings (missed recordings) and total at all sites over study period from January 6, 2006 to December 31, 2006. List of rain events, total recordings (missed recordings) and total at all sites over study period from January 6 - December 31, 2006.

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Table 2. Results of logistic regression analysis for abiotic variables at 2100 h (temperature, relative humidity, change in barometric pressure, percent moon illumination, and daily precipitation) versus calling activity over study period January 6 – December 31, 2006.

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Table 3. Results of logistic regression for abiotic variables (temperature, relative humidity, barometric pressure, precipitation and percent moon illumination) versus calling activity every 30 minutes (1800-0600 h) over study period January 6 – December 31, 2006.

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List of Figures Figures

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Chapter 1 Figure 1. Location of five ponds under investigation in the municipality of Quebradillas, Puerto Rico, northwest karst zone (image on left: Ikonos 2004 state plane 1983, image on right: USDA 2001). The four ponds to the east are historic Bufo lemur breeding locations, the single pond located to the west is considered a future captive bred toad release site......................................................35 Figures 2a and 2b. State of pond 1 (located in Bo. San José, Quebradillas) in October 2005 compared to March 2007. ...................................................................36 Figures 3a and 3b. State of pond 2 (located in Bo. Cocos, Quebradillas) in March 2005 compared to January 2007. ...............................................................................37 Figures 4a and 4b. State of pond 3 (located in Bo. Cocos, Quebradillas) in March 2005 compared to October 2006................................................................................38 Figures 5a and 5b. State of pond 4 (located in Bo. Cocos, Quebradillas) in September 2005 compared to December 2006. .........................................................39 Figure 6. State of pond 5 (located in Las Talas, eastern Quebradillas) in August 2005... 40 Figure 7. Average calling activity per species at the five ponds in the municipality of Quebradillas (Site 1 – 4: Jan. – Dec. 2006, Site 5: Jan.– Jun 2006)......................41 Figures. 8a and 8b. Comparison of land use changes in the municipality of Quebradillas, Puerto Rico, from 1963-2001 as viewed through satellite images and analyzed in ArcView 3.2 by Rosanne Medina (2004, unpublished report).........................................................................................................................42 vii

Chapter 2

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Figure 1. Location of five ponds under investigation in the municipality of Quebradillas, PR, northwest karst zone (image on left: Ikonos 2004 state plane 1983, image on right: USDA 2001). The four ponds to the east are historic Bufo lemur breeding locations, the single pond located to the west is considered a future captive bred toad release site......................................................77 Figure 2. Illustration of average calling activity (1 = presence and 0 = absence) per species over the study period. Data include the 5 study sites over a 24 hour period. Anti = E. antillensis, Coqui = E. coqui, Coch = E. cochranae, Lepto = L. albilabris, Bufo = B. marinus, Osteo = O. septentrionalis....................................78 Figure 3. Average calling activity per species at each of the five ponds over the study period. Ponds 1-4 were monitored from January 6 – December 31, 2006. Pond 5 was monitored from January 6 – June 2, 2006. .............................................79 Figure 4. Comparison of average temperature readings between South East Regional Climate Center (SERCC) from 1955 - 1975 from Quebradillas and average Hobo recordings taken at the study sites from January 6 - December 31, 2006......................................................................................................................80 Figure 5. Average temperature and relative humidity readings from Hobos placed at study sites 1 - 4 in Quebradillas from January 6 - December 31, 2006.....................81 Figure 6. Comparison of average monthly precipitation between data collected from South East Regional Climate Center 1955-2000 in Quebradillas and that collected by rain gauges at the study site from January 6 – December 31, 2006. .....82

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Figure 7. Comparison of total precipitation (mm) and barometric pressure cycles (kPa) from January 6 - December 31, 2006...............................................................83 Figure 8. Comparison of precipitation and drop in barometric pressure over 11 weeks of rain during study period from January 6 - December 31, 2006..................84 Figure 9. Comparison of changes in barometric pressure for week of rain over eleven rains events during study in Quebradillas in 2006. ........................................85 Figure 10. Average amphibian calling activity during each rainfall event over study period in 2006: Event 1 = Jan 12 -18; Event 2 = Mar 3 – 9; Event 3 = Mar 28 Apr 3; Event 4 = Apr 19 – 25; Event 5 = May 7 – 13; Event 6 = May 27 - Jun 2; Event 7 = Jun 5 – 11; Event 8 = Aug 5 – 11; Event 9 = Sept 10 – 16; Event 10 = Sept 26 – Oct 2; Event 11 = Nov 23 – 29..........................................................86 Figure 11. Average amphibian calling activity during each day during the week of rain over study period in 2006: Day 1 – 3 were days before the main rain event, day 4 was the main day of rain, day 5 -7 were days following the day event. ..........87 Figure 12. Average rainfall over seven days of rain event. Days 1-3 are days before the rain event. Day 4 is the day of main precipitation. Days 5-7 are days following rainfall. ..............................................................................................88

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CHAPTER 1 Description of Landscape and Species Presence at Puerto Rican Crested Toad (Bufo [Peltophryne] lemur) Northern Breeding Ponds

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ABSTRACT The apparent decline in amphibian populations worldwide has driven the need to establish more effective monitoring strategies. Puerto Rico has experienced the loss of three species of amphibians, and a decline in six others including the island’s only endemic toad, the Puerto Rican crested toad (Bufo lemur). Puerto Rican crested toads were once distributed along the northern and southern karst belt of the island but the last known northern individuals were observed in 1992. In this study a survey was carried out in the north of Puerto Rico over the course of a year with an aim to survey amphibians at four documented Puerto Rican crested toad breeding ponds and at a potential captive bred toad release site, compare habitat characteristics, land-use changes, the presence of other pond-dwelling organisms, and develop recommendations on future search protocols and captive bred toad reintroductions. Six species of amphibians, including two exotics (Bufo marinus and Osteopilus septentrionalis) were detected over the 2006 survey period. Puerto Rican crested toads were not detected. Land use change analysis indicated a 21% increase in urban development contiguous to the ponds between 1963 and 2001, but no development between the ponds and Bellaca creek. Additional land use change leading to habitat fragmentation and the presence of invasive amphibians could have played a role in stressing extant Puerto Rican crested toad populations. Without the availability of suitable habitat and protection it would seem impractical to recommend the release of captive bred individuals to the area. Continued and expanded searches may still yield extant individuals.

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RESUMEN La disminución aparente de poblaciones de anfibios a nivel mundial motiva el establecimiento de estrategias de monitoreo más eficientes. Tres especies de anfibios han desaparecido de Puerto Rico, y se han documentado declives en otras seis especies, incluyendo al único sapo endémico de la isla, el sapo concho puertorriqueño (Bufo lemur). El sapo concho puertorriqueño se distribuyó históricamente en la zona cársica del norte y sur de la isla, aunque los últimos individuos del norte se observaron en 1992. Durante este estudio se llevó a cabo un monitoreo durante un año en cuatro charcas de reproducción y una zona de potencial de liberación al norte de Puerto Rico. Se compararon características de hábitat, cambios de uso de terreno, presencia de otros organismos acuáticos, y se desarrollaron recomendaciones para protocolos de búsqueda y liberación de renacuajos producto de reproducción en cautiverio. Seis especies de anfibios, incluyendo a dos especies exóticas (Bufo marinus y Osteopilus septentrionalis) se detectaron durante el monitoreo de 2006. No se detectó al sapo concho puertorriqueño. Análisis de cambio en uso de terreno indicaron que el desarrollo urbano aumento un 21% cerca de las charcas entre 1963 y 2001, aunque no hubo desarrollo de terreno entre las charcas y la quebrada Bellaca. El cambio en uso de terreno que fragmentó el hábitat y la presencia de especies invasoras pudieron añadir estrés a las poblaciones restantes de Bufo lemur. Sin hábitat adecuado o protección parece poco práctico recomendar la liberación de individuos de propagación en cautiverio en el área. Se podrían aún encontrar individuos por medio de búsquedas continuas y de mayor cobertura.

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INTRODUCTION The Global Amphibian Assessment, carried out by the Declining Amphibian Population Task Force, estimates that nearly one-third (32%) of the world’s amphibian species are currently under threat (GAA 2006). However, obtaining a comprehensive list of species is difficult and lack of baseline data leaves no information over which to measure population changes (Heyer et al. 1994). Finding efficient ways to monitor species and inventories become increasingly important as the scientific community struggles to understand reasons behind amphibian declines. Habitat loss and degradation, pollution, disease and the introduction of invasive species are listed as the top reasons for species decline (GAA 2006). Puerto Rico has 19 native amphibians: 18 leptodactylids and 1 bufonid. Of these, 3 members of the genus Eleutherodactylus have not been sighted in over 10 years (E. karlschmidti, E. jasperi, and E. eneidae) and at least 6 others are considered under threat (Burrows et al. 2004). Puerto Rico’s only endemic toad, the Puerto Rican crested toad (Bufo [Peltophryne] lemur), has also suffered a population decline. The distribution of crested toads, described by Cope in 1868, was once documented along the northern and southern karst regions of Puerto Rico and on Virgin Gorda (where they have not been observed since the 1930’s). Crested toads in Puerto Rico were considered extirpated after 1930 until they were rediscovered in the northern municipality of Isabela in 1966 (García Díaz 1967). From 1974 to 1992 crested toads were observed breeding at artificial ponds in the neighboring municipality of Quebradillas (Rivero 1980, Estremera unpublished notes). In 1984, crested toads were discovered in the south, breeding in ephemeral ponds at the Guánica State Forest (Moreno 1985). Today, these ponds in the south are the only known remaining natural crested toad breeding areas. The Puerto Rico Department of Natural and Environmental Resources considers the southern population 13

endangered and the northern population as critically endangered. The species was listed as threatened by the US Fish and Wildlife Service in 1987 (USFWS 1992). Puerto Rican crested toads are difficult to monitor presumably due to their semi-fossorial lifestyle. They have been documented in arid or semi-arid, rocky areas with an abundance of limestone fissures and cavities in well drained soil (USFWS 1992). Individuals have been found under rocks by Richard Thomas (personal communication), in river beds (García-Díaz 1967), grass fields (Moreno 1985), and rock cracks and crevices (Johnson 1994, Rivero 1998) where they are believed to seek refuge to retain humidity. This cryptic species is most easily detected at the breeding ponds where adults congregate to mate during explosive breeding events. Population estimates and monitoring are usually conducted at this time. Most documentation of habitat use and monitoring has centered on the southern population because the area is accessible and personnel have been available (Johnson 1994, Moreno 1985, Canals unpublished field notes, Matos unpublished masters thesis). However, much less information is available on the current status of northern habitat and population. The aims of this study were: 1)- to survey amphibians at four documented Puerto Rican crested toad breeding ponds in the northern municipality of Quebradillas and at a potential captive bred toad release site, 2)- to compare habitat characteristics and land-use changes, 3)- to inventory pond-dwelling invertebrates and vertebrates at each breeding pond, and 4)- to develop recommendations on future search protocols and captive bred toad reintroductions.

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MATERIALS AND METHODS Study Site Although the four historic breeding ponds are in relative proximity to each other and are all located in grassland (Fig. 1), each has a unique set of local habitat characteristics, inhabitants and history. Each of these ponds was built to retain water permanently, for use by cattle (USFWS 1992). The following section discusses each pond in reference to the history of Bufo lemur.

Site 1 – Finca los Martínez Pond 1 is located in an active cattle farm once known as “El callejón de Doña Rosa” in Barrio San José, to the northwest of Bellaca creek. According to a soil survey by USDA (1975), soil at this site consists of Matanzas clay, generally found on foot slopes and valleys between limestone hills. This soil type has generally been used to build residences and industry or plant with sugarcane. Today the area is actively used by cattle and contains mostly grazed grasses and scattered Croton rigidus and Lantana involucrata shrubs. A few trees and larger bushes dot the landscape and surround the pond. The pond is located on the hill where water gathers during rain events. The pond is 6 m x 7 m and slants gently at the south to allow cattle access. The pond can fill to just over 1 m and drains over its north border down to Bellaca creek located 135 m to the northeast. The pond is actively used by cattle and excrement appears easily washed into the pond during rain events. The depth of the pond varied during field visits over 2006 (see Figures 2a and 2b). During dry season the pond has been known to dry completely (Estremera personal communication).

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Crested toads were reported breeding at this pond between 1976 and 1980. Toads were also seen traveling by Ernesto Estremera up to the pond from a ravine approximately 50 m to the west. When toads were first located, the area was more densely covered by trees and some cattle were present, but otherwise the area has not changed significantly (Estremera personal communication).

Site 2 – Charca de los Jacintos Charca de los Jacintos is located in a creek bed behind private property in an area known as Hoyo Brujo. Soil maps (USDA 1975) indicate the soil type is a combination of Matanzas clay and Limestone rock land known as Matanzas-Limestone rock “generally used for grazing, woodland or wildlife habitat due to the large number of outcrops and rocks”. The pond today is covered in water hyacinth, Eichhornia crassipes (Mart.) Solms, a vascular plant native to Brazil and considered a noxious weed (USDA 2007). The Center for Aquatic and Invasive Plants (2007) states water hyacinth “greatly reduces biological diversity: mats eliminate native submergent plants by blocking sunlight, alter emergent plant communities by pushing away and crushing them, and also alter animal communities by blocking access to the water and/or eliminating plants the animals depend on for shelter and nesting”. The plant was not present when toads were first discovered in 1974 (Estremera personal communication). This small pond (4.5 x 5 m) is otherwise generally exposed to the sun. The southern aspect is open and shallow even at its deepest end which might fill as much as about 0.5 m before water pours around the pond and drains into Bellaca creek 35 m away. The western side of the pond is exposed rock face with limestone crevices and refuges. A small pig farming operation has been

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set up on private property about 10 meters from the pond. Over the course of 2006 the pig farm increased from 1 to 23 individuals. Waste from these animals flows directly to the pond and continues into the creek (see Figures 3a and 3b). Puerto Rican crested toads were first documented at this site in 1974, then in 1975 and 1977 (Estremera unpublished notes), but despite return visits no individuals have been since observed.

Site 3 – Charca de los González This area is also Matanzas-Limestone rock (USDA 1975). The pond is located about 160 m to the south of Bellaca creek and did, at some point, capture rain water flowing from the area. However, the pond is now bordered immediately to the south by a housing development. The pond is large (7 x 15.6 m) and fills to just over 1 m at its deepest end during heavy rain events. The pond is shaded by a heavy canopy of trees and immediately surrounded by a variety of shrubs and small trees (Figures 4a and 4b). This is the site of the last Puerto Rican crested toad sighting in 1992. Toads were seen at this site in 1977, 1980, and 1985, when the area was not yet developed and was still a combination of forest and grasslands. This pond was monitored by Ernesto Estremera for years (personal communication) but no toads were documented after 1992. The area and pond have undergone many changes: the area was deforested to make room for a church that was never built and the site was used as a junk yard, the pond was drained by locals to limit the production of mosquitoes. Conversation with neighbors suggests chemicals, such as bleach, are still occasionally added to the pond to combat mosquitoes.

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Site 4 – Charca de los Rodríguez Pond 4 (also known as Charca de Papo) is located in an undeveloped grass field, within 55 m of Bellaca creek. The area is characterized as Limestone outcrop with “hard, massive, gray and pinkish-gray limestone crops out of 75 to 100% of the surface” with a 0-60% slope. Its use is restricted to wildlife or water supply. Vegetation surrounding the pond is mostly pasture which does not appear to have changed much according to aerial photographs of the area. This is the largest (9.2 x 10.5 m) and deepest of the northern historic breeding ponds. The pond appears to retain water year round and can reach a depth of up to 2 m. The north end is shaded by trees that overhang from a back wall of limestone rock containing many exposed cavities. The pond is located in a depression that naturally catches water flowing down the valley (Figures 5a and 5b). Engravings in the cement state the pond was built in the 1940s. Crested toads were documented at this site in 1976, 1977, 1978, 1980 and 1982, and captive bred toadlets were also released at this site in 1983 (Estremera unpublished notes). According to Estremera (personal communication) and evidenced by aerial photos, aside from the disappearance of grazing cattle the area has not been altered and the pond has never been seen empty.

Site 5 – Las Talas Puerto Rican crested toads were never documented at this site. However the area has been considered a future release site for captive bred toads based on its habitat characteristics and proximity to the municipality of Isabela, where toads were observed in 1966 and 1982. The pond is located west of Quebradillas and 1 km east from the Guajataca river in a forested sector

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of limestone outcrop known as Las Talas (Figure 6). Carvings in the cement date its construction to 1943. The pond is 9 x 5 m and sits directly in a small creek from which it captures rainwater to fill up to 1m at its southern end. The area is heavily forested and contains endemic plant species such as Beautiful goetzea (Goetzea elegans), which at one point was being removed by someone from the local community.

Anuran Vocalization Recordings Automated data recorders (Frogloggers) were set up to record amphibian calling activity at each of the study sites. Sony® Hi-MD froglogger systems (Sony® Hi-MD MZ-RH10 digital portable recorder, controller, waterproof case and cables) were chosen based on their inconspicuous size and mid-range cost. Each logger was equipped with a high quality Sony® ECM-MS908C Stereo Condenser Microphone to ensure quality recordings and minimize misidentification of species. Each froglogger was located within 5 meters of the selected pond with a microphone placed 1 to 2 meters above ground and pointed towards the pond as recommended by Bridges and Dorcas (2000). All equipment was hidden, chained to trees and camouflaged to prevent theft. Frogloggers were preprogrammed to record 14 seconds every 30 minutes over a 24 hour period. I conducted weekly field visits to download the information on the loggers and replace batteries. Nightly calling activity from 1800 to 0600 h were viewed as a spectrogram using Raven Light developed by the Cornell Ornithology Laboratory and this was used to identify species. Calls were categorized as 1= presence and 0 = absence. For each species I used a Kruskal-Wallis

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statistical analysis to test the null hypothesis of no difference in calling activity among ponds. If significant differences were documented (p < 0.05), I applied pairwise tests to compare the ponds. Climate data were collected for one year and periods of heavy rain (over 25.4 mm of rain during a 24 hour period) were considered for analysis. The four historic ponds were monitored from January 6, 2006 until December 31, 2006. The fifth site was monitored from January 6 – June 2, 2006. Calling activity per species at each site was examined for one week over each rain event.

Habitat Evaluation of Study Sites Study sites were located in maps using geographic coordinates collected by Global Positioning System (Garmin® eTrexLegend) and overlaid on aerial photographs from 1963 and Ikonos 2001 satellite images. Images were examined with ArcView 3.2, municipal records reviewed and residents interviewed to assemble the history of local land use changes from 1930’s – 2001. Information layers on rivers (US EPA 1988), soils (USDA 1975), and land-use analysis carried out by graduate student Rosanne Medina (unpublished data) were overlaid on satellite images to examine habitat characteristics at each pond and surrounding area. Layers were projected to Puerto Rico State Plane using North American Datum 1927 in 30 x 30 m pixels.

Pond Sampling An inventory of pond-dwelling vertebrates and invertebrates at each pond was carried out in October 2005. Specimens were captured using three different sized nets. I swept nets through the center, on the surface and along the edge of each pond twice. Contents collected from each

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sweep were examined, placed in a container, and taken to the lab for identification where they were examined again and placed in 70% ethanol. Nets were cleared between ponds. At the laboratory all specimens were identified to the lowest possible taxonomic level.

RESULTS Anuran Calling Activity Three families of anurans, Leptodactylidae, Bufonidae and Hylidae, were documented during the eleven heavy periods of rain recorded over the sampling period (January 6, 2006 to December 31, 2006). The four leptodactylids recorded are native (Eleutherodactylus antillensis, E. coqui, E. cochranae and Leptodactylus albilabris). The remaining two families are represented by introduced species: Bufo marinus and Osteopilus septentrionalis. Puerto Rico’s only endemic toad, Bufo lemur, was not detected. Kruskal-Wallis analyses rejected the null hypothesis of no difference in calling activity among ponds for each species, and all-pairwise comparison tests then compared the calling activity of ponds. Four of six species were documented at each pond. The Antillean coqui, Eleutherodactylus antillensis, called frequently at every pond: a difference was detected between pond 1 and pond 3 with the most activity. Differences were detected for the common coqui, E. coqui, calling activity at all ponds: calling was highest at pond 5 and lowest at pond 1. Calling activity for the whistling coqui, E. cochranae, was significantly higher at site 5 and this species was not detected at ponds 1 or 2. White-lipped frogs, Leptodactylus albilabris, called at all the ponds but significantly less at pond 1. Statistical analysis illustrated that marine toads, Bufo marinus, called most actively at pond 4, and were not active at pond 2. Cuban treefrogs, Osteopilus septentrionalis, were detected calling at all ponds, but most actively at pond 2. 21

Figure 7 illustrates the calling activity of each species per pond and Appendix A outlines Kruskal-Wallis results. Overall, less activity was recorded at pond 1, whereas ponds 4 and 5 appeared to be the most active. The presence of invasive species at these ponds will be discussed in further detail.

Description of Historic Landscape Examination of satellite images indicates ponds are located within the northern karst belt of Puerto Rico. The four historic breeding ponds to the east of Quebradillas are less than 100 meters in elevation and are located within 100 meters of Bellaca creek. The fifth pond is located at an elevation of 113 m in a creek bed approximately 1 km east of Guajataca river. Soils underlying the ponds consist of a mixture of limestone outcrop, Matanzas limestone outcrop, and Matanzas clay. Aerial photos (1936 - 1955) indicate an agricultural landscape around the ponds, which according to engravings in the cement, were built in the 1940s. Each pond is a man-made cement structure varying in size from 4.5 x 5 m to 9.2 x 10.5 m. A comparison of aerial photographs (1963) and satellite images (2001) indicates the grassland area between the four ponds and Bellaca creek has not been altered significantly. However, analysis of images showed rural development has altered much of the habitat within 1 km of the creek (Figures 8a and 8b). Most development has occurred closest to ponds 2 and 3, which are now located immediately adjacent to housing developments. A summary of pond details and habitat characteristics is outlined in Table 1.

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Inventory of Pond-Dwelling Organisms Biological samples collected from the ponds were composed mostly of adults and larvae of the following insects: Odonata (Libellulidae), Hemiptera (Notonectidae, Belostomatidae, Pleidae, Corixidae, Gerridae), Coleoptera (Dytiscydae), and Diptera. Snails of the family Physidae and Ampullaridae and leeches of the species Helobdella punctatolineata were also collected. The least number of individuals and species was collected from ponds 1 and 2. Overall, a greater number of specimens and species were collected at ponds 3, 4 and 5. Turtles, fish and amphibians were also collected during the inventory, including a redeared slider (Trachemys scripta); tilapia (Oreochromis) and minnows (Poeciliidae); and Whitelipped frog, marine toad and Cuban treefrog tadpoles. A complete list of collected specimens is included in Appendix B.

DISCUSSION Species Composition at Sites Six species of amphibians were detected while surveying the historic Puerto Rican crested toad breeding ponds. Species composition and calling activity varied between sites with only four species detected across all sites. The make-up of vertebrate and invertebrate organisms at each pond and landscape changes offer clues with which to speculate on possible reasons for the disappearance of Puerto Rican crested toads in the area. Three of the four species of leptodactylids detected during this inventory develop directly and are of island-wide distribution. Their presence at each site is not dependent on pond conditions or directly affected by pond-dwelling organisms. Antillean coquis were detected

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calling at each site, not surprisingly since this species is distributed island-wide particularly in lowland areas (Joglar 1998). This species generally calls from low lying vegetation about 0-1 m above ground (Drewry and Rand 1983). The common coqui was also detected at each site (less actively at site 1) and is found in all habitat types across the island. This species uses trees, shrubs, bromeliads, rocks, detritus, and tree trunks among others as calling sites and refuges (Joglar 1998). The whistling coqui, a small species documented in lowland areas up to 335.8 m in elevation, generally calls from bromeliads, grasses and vegetation up to 2.5 m and 8 m in the dry forest (Joglar 1998). This species was detected mostly at sites 3, 4 and 5. The fourth member of this group, the White-lipped frog, is a ubiquitous semi-aquatic species also distributed islandwide (Rivero 1998) and was also detected at all sites. Overall, site 1 was the least popular calling site, particularly for the group of native anurans. At this active cattle ranch, grasses are kept short by grazing cattle and shrubbery is reduced to unappetizing spurts of Croton rigidus leaving few perches available for arboreal frogs. Besides the pond, this area is located upland with few surrounding crevices or depressions to accumulate water and provide appropriate moist refuges. Site 5, on the other hand, was a forested area offering a wider variety of refuges and was the most active calling site for this group. Marine toads were the only species not detected at site 5. The habitat preference and reproductive activity of the two exotic species documented in this inventory (marine toads and Cuban treefrogs) are discussed in further detail as the effect of introduced species is considered a large threat to biodiversity (GAA 2006, Meshaka 2005) and of potential interest in the case of missing Puerto Rican crested toads. Successful exotic species have common characteristics, among these they adapt easily to living in human developed habitats, disperse easily, and are highly fecund (Meshaka 2005).

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Marine toads are considered one of the most successful colonizing invasive species (Meshaka 2005). They were introduced to Puerto Rico in the 1920’s from Jamaica to control the larva from the May beetle (Phyllophaga portoricensis) that constantly attacked sugarcane plantations and were soon transported to sugar cane fields throughout Puerto Rico due to their success in controlling this pest (Lever 2001). Marine toads are mainly nocturnal animals that seek daytime retreats in underground shelters with damp soil, preferably close to water for regular hydration - a factor which may be limiting in the dry season (Lever 2001). They prefer to breed in temporary, shallow and warm water (Hero and Stoneham 2005). In these temporary (or sometimes permanent) bodies of water females lay between 8,000 – 30,000 black eggs in strings. As per Lever (2001) marine toad tadpoles feed mostly on algae and have been known to practice cannibalism; upon metamorphosis they switch to a carnivorous diet which includes terrestrial arthropods, and crabs, mollusks and also small vertebrates. Studies suggest the presence of marine toads is detrimental to native anuran populations (Punzo and Lindstrom 2001). In 2005, graduate student Ingrid Flores (personal communication) observed a juvenile marine toad with a newly metamorphed crested toad in its mouth. Observations by Miguel Canals (personal communication) at the Guánica State Forest, where crested toads and marine toads breed in the same pond, also suggest that marine toads compete with crested toads for access to refuges and resources at the breeding ponds. The Cuban treefrog is another documented frog-eater and expanding colonist present at these ponds (Meshaka 2001). Cuban treefrogs were thought to arrive in Puerto Rico in the 1950’s through accidental introduction (Smith 2005). They were first documented on the northwest side of the island but their range has expanded and will most likely continue to expand given the

25

availability of habitat and its life history (Meshaka 2001). Cuban treefrogs are explosive breeders with females laying up to 16,000 eggs (Meshaka 2001). Meshaka (1996) studied treefrogs living near buildings and reported a combination of arachnids and insects (mostly roaches), crustaceans, gastropods, amphibians and small lizards in their diet. He suggested the large quantity of roaches in their diet indicates an availability of these items on buildings, and that Cuban treefrogs prey upon other potential competitors (other frogs and lizards) to assure a constant food supply. Anecdotal evidence (Bartlett 1967) suggested that native herpetofauna in Florida has suffered from the introduction of Cuban treefrogs as a result of adult predation. Kevin Smith (2005) studied the effect of both marine toads and Cuban treefrogs on growth and development of other anurans in Florida. He found that Cuban treefrog tadpoles significantly delayed the growth rate and metamorphosis of native anurans (Bufo terrestris and Hyla cinerea). Other experiments by Smith (2005) suggest Cuban treefrog tadpoles will eat other anuran larvae when held in large densities with no available food supply. Interestingly, during this study, at these smaller ponds, Cuban treefrogs and marine toads seemed to dominate one or other of the study sites, almost suggesting one species does not fare well in the presence of the other. In their native Venezuela, studies indicate that although marine toads co-occur with 21 other anurans, they are often found alone or with few other species, indicating they chose times and locations when other species are not active or other species avoid marine toads (Hero and Stoneham 2005). In 2006, marine toads were observed at each of the breeding ponds over the year but were only detected calling at ponds 1, 3 and most notably at pond 4 where marine toad adults and tadpoles were often encountered during field visits. Few Cuban treefrogs were detected calling at this site. On the other hand, Cuban treefrog adults were detected most frequently at pond 2, where although marine toads were observed on field visits,

26

they were not detected calling. One possible reason for this apparent separation of habitats could be habitat preference itself. Marine toad eggs are toxic and tadpoles are unappetizing to many species (Hero and Stoneham 2005, Lever 2001, Wassersug 1971) so eggs are safe in ponds with the presence of fish and other predacious aquatic invertebrates as seen in pond 4, where Cuban treefrog tadpoles might be vulnerable. Failure to detect marine toads calling at pond 2 is difficult to explain other than their possible preference for higher water levels or competitive exclusion by Cuban treefrog tadpoles. Then there is the presence of invertebrate and other vertebrates at the ponds to consider. These man-made permanent ponds were slowly colonized by an assortment of flora and fauna (either naturally or by human introduction). Our study revealed a range of predacious organisms inhabiting the ponds: mainly members of Odonata, Coleoptera and Hemiptera. Carnivorous dragonfly larvae of the family Libellulidae were detected in large numbers at ponds 4 and 5. A few larvae of beetles of the family Dysticidae were also detected in ponds, 1, 2, and 5. Giant water bugs (Belostomatidae), also known to predate on amphibian larvae, were documented at pond 4. Turtles were collected during a survey at pond 1 and were often seen basking in the sun at pond 1 and 4. Guppies (Poeciliidae) were captured at ponds 3 and 4 and Oreochromis sp. cichlids that grew to 4 inches over the course of a year were captured at pond 4. All of the ponddwelling arthropods documented at pond 3 were larvae of terrestrial insects; in other words, no aquatic residents were collected, indicative of poor water quality.

Landscape Changes Each of the ponds considered in this study is a man-made cement structure built in the 1940s to facilitate rain water catchment and retention for cattle use (USFWS 1992). Ponds were 27

built in a natural depression or along creek beds where water would naturally flow and accumulate. Many of these ponds retain water throughout the year and have been colonized by a variety of species. Puerto Rican crested toads are thought to breed in ephemeral ponds during heavy rain events as observed at the Guánica State Forest (USFWS 1992). In the north, however, crested toads have only been documented breeding at these permanent sites. Johnson (1994) suggested these permanent man-made ponds may have been considered secondary breeding sites by species such as crested toads when traditional ponds were unavailable due to habitat alteration or weather changes. There are no records of Puerto Rican crested toad breeding events in the municipality of Quebradillas prior to 1967. Early in the century, toads in the north were sighted in river beds and grass fields. From 1931-1966 biologists lamented the loss of this Puerto Rican endemic, until they were rediscovered in the creek bed of La Sequia, Isabela, by García-Díaz (1967). Toads were then observed in Barrio Cocos, Quebradillas, in 1974 and three additional breeding sites in Quebradillas (subjects of this study) were discovered. The historic breeding ponds in Quebradillas were monitored from 1974 onward but the last crested toad in the north was seen in 1992. Crested toads were also located in the south at the Guánica State Forest in 1984. Puerto Rico was still mostly an agricultural society early into the twentieth century, producing sugarcane, coffee, tobacco and other miscellaneous crops (Dietz 1986). Sugarcane was Puerto Rico’s most important agricultural product with approximately 237,758 acres devoted to its production in 1929 (Dietz 1986). Land not suitable for agriculture production was left forested or as pasture for cattle grazing. Aerial photographs from 1936 show an agricultural patchwork quilt over most of the coastal municipality of Quebradillas, with little urban development. Aerial photos and discussion with the local Soils Conservation Office also suggest

28

that most of the land in the study area immediately bordering Bellaca creek was and still is grassland. Johnson (1994), suggested crested toads used Bellaca creek as a refuge and ascended to the breeding ponds during rain events. No development has taken place in the area so far to impede this voyage. In the 1970’s Estremera (personal communication) documented toads moving from a nearby lowland creek with limestone crevices up to pond 1 about one hundred meters away. It is possible that crested toads are still present in Bellaca creek but disturbances at these traditional breeding ponds may have caused them to shift their breeding activity to other sites. Most landscape changes in the area have occurred in the vicinity of the ponds and Bellaca creek. Analysis of land-use in the municipality of Quebradillas by Roseanne Medina (2004 unpublished report) showed a decrease of 29% in grass areas and agricultural land from 1963 to 2001, whereas urban development increased by 21% (Figure 8). Most major urban development completely surrounds the creek and ponds, creating a barrier to any type of migration. Field observations suggest crested toads may travel from 2 km (Johnson 1994) to 4 linear km (Moreno 1985) from the breeding ponds at Guánica to the limestone hills to seek refuge in caves and limestone cavities. If the north toads also sought refuge in limestone crevices surrounding these breeding ponds instead of Bellaca creek, they might have slowly found their path from these crevices to the breeding ponds obstructed by urban development. As development increased, fewer corridors to the ponds were available, eventually cutting off access to breeding sites. Development in the area has been so extreme that some ponds are now directly bordered by housing complexes. Pond 3 lies directly behind a housing development and pond 2 in immediate vicinity of a pig farming operation. This close proximity to human poses many risks.

29

The ponds have at times been drained in a human effort to control mosquito propagation (Estremera personal communication). A neighbor also suggested chlorine is sometimes added to limit the production of mosquitoes, which might account for a few floating marine toad cadavers I encountered during field visits. Rain and runoff from grasslands commonly sprayed with herbicides, chemical fertilizers and pesticides would also add to possible contamination (USFWS 1992). Estremera (personal communication) remembers herbicides being sprayed in the area when he was searching for crested toads. It is interesting to note that marine toad populations started to decline in the mid-1930’s possibly due to their proliferation and subsequent obliteration of the white grub upon which their diet relied, and prolonged droughts that dried up many breeding ponds (Lever 2001). Following a decline in marine toads, the white grub staged a recovery in the late 1930’s and farmers resorted to the use of benzene hexachloride and other chemicals to control this beetle larva (Lever 2001). It was around this time in 1931 that Puerto Rico’s only endemic Bufonid, Bufo lemur, was last observed, until it was rediscovered in 1966.

RECOMMENDATIONS In summary, no Puerto Rican crested toads were documented over the study period. Two invasive species were detected. Unfortunately, each species has a reputation for affecting native wildlife in one form or another. The need to understand the biology and distribution of invasive species is equally as important as that of endemics. It is important to document the patterns of introduced amphibians in Puerto Rico to better understand the impact of these species on native fauna. Meshaka (2005) suggested that invasive species have been successful colonizers partially

30

due to our disinterest in them. Enough evidence points to the damage caused by these species that we should focus more research in this area and increase methods of control. Although no significant changes have occurred between the ponds and the creek, urban development at Site 2 and 3 make these areas unsuitable for captive breeding reintroductions. Of the traditional breeding ponds, Site 1 offers the most potential due to its isolated location, low assortment of permanent inhabitants and its ephemeral nature. Site 4 could also be considered a potential release site, if more ephemeral ponds are built. Site 5 in Las Talas or an equally isolated area with undisturbed access to rock crevices is also a potential. However, additional surveys should be carried out at this pond, if considered for reintroductions, as leeches were detected during our survey and these could disturb the breeding success of pond-breeding amphibians. If any of these sites are considered for reintroductions, they should be managed aggressively to control invasive species. The search for toads at these ponds is scheduled to continue for another year and recommended to continue for 5 years (Johnson personal communication). The search should be expanded to include Bellaca and La Sequia creeks where toads may have returned to natural breeding sites. Recent collaboration between the Department of Biology and the Electrical and Computer Engineering Department (WALSAIP project) at UPR Mayagüez proposes to set up equipment to monitor amphibian populations in areas of interest. Additional recommendations include distributing compact discs with toad calls to local communities and offering rewards to those who hear and record the species. Education programs set up by the Puerto Rican Crested Toad Recovery Group could encourage schools to become involved in acoustic monitoring.

31

LITERATURE CITED Bartlett, R.D. 1967. Notes on introduced herpetofauna in Dade County, Florida. Bulletin of the Pacific Northwest Herpetological Society 2:5–7. Bridges, A.S. and M.E. Dorcas. 2000. Temporal variation in anuran calling behavior implications for surveys and monitoring programs. Copeia 2000:587-592 Burrowes, P.A., R. L. Joglar and D.E. Green. 2004. Potential Causes for Amphibian Declines in Puerto Rico. Herpetologica 60(2):141-154 Center for Aquatic and Invasive Plants, University of Florida and Sea Grant. 2007. Non- Native Invasive Aquatic Plants in the U.S. http://plants.ifas.ufl.edu/seagrant/eiccra2.html. Drewry, G. E. and A. S. Rand. 1983. Characteristics of an acoustic community: Puerto Rican frogs of the genus Eleutherodactylus. Copeia 1983:941-953. Dietz, J. L. 1986. Economic History of Puerto Rico. Princeton University Press, New Jersey. García Díaz, J. 1967. Rediscovery of Bufo lemur (Cope) and additional records of reptiles from P.R. Stahlia 10:1-6. Global Amphibian Assessment. 2006. Declining Amphibian Population Task Force. http://www.globalamphibians.org/summary.htm. Hero. J.M. and M. Stoneham. 2005. Bufo marinus. In Amphibian Declines: The Conservation Status of United States Species, ed. M. Lannoo, pp 419-422. University of California Press, Los Angeles, CA. Heyer, W. R., M. A. Donnelly, R. W. McDiarmid, L.C. Hayek and M. S. Foster (eds). 1994. Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians. Smithsonian Institution Press, Washington, D.C. Joglar, R. L. 1998. Los coquies de Puerto Rico: su historia natural y conservación. Editorial de la Universidad de Puerto Rico, San Juan. Johnson, R.R. 1994. Model programs for reproduction and management: ex site and in situ conservation of toads of the family Bufonidae. In Captive Management and Conservation of Amphibians and Reptiles, SSAR, Contributions to Herpetology, volume 11, eds. J.B. Murphy, K. Adler and J.T. Collins, 243-254. Ithaca, New York. Lever, C. 2001. The Marine Toad. The History and Ecology of a Successful Colonist. Westbury. Academic and Scientific Publishing, Otley, West Yorkshire.

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Meshaka, W. E., JR. 1996. Diet and the colonization of buildings by the Cuban Treefrog, Osteopilus septentrionalis. Caribbean Journal of Science 32:59–63. ________. 2001 The Cuban Treefrog in Florida – Life History of a Successful Colonizing Species. University Press of Florida, Gainesville, Florida, USA. ________. 2005. Exotic Species. In Amphibian Declines: The Conservation Status of United States Species, ed. M. Lannoo, 271-274. University of California Press, Los Angeles, CA. Moreno, J. 1985. Notes on Peltophryne lemur Cope. Unpublished document. Peterson, C. R., and M. E. Dorcas. 1994. Automated data acquisition. In Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians, eds. Heyer, W. R., M.A. Donnelly, R.W. McDiarmid, L. C. Hayek and M.S. Foster, 47-57. Smithsonian Institution Press, Washington, D.C. Punzo F., L. Lindstrom. 2001. The Toxicity of Eggs of the Giant Toad, Bufo marinus to Aquatic Predators in a Florida Retention Pond. Journal of Herpetology. 35(4):693-697. Rivero, J. A. 1998. The Amphibians and Reptiles of Puerto Rico. Editorial de la Universidad de Puerto Rico, San Juan, Puerto Rico. 2nd edition. Rivero, J. A., H. Mayorga, E. Estremera, and I. Izquierdo. 1980. On Bufo lemur (Cope). Caribbean Journal of Science 15:33-44 Smith, Kevin G., 2005. Effects of Nonindigenous Tadpoles on Native Tadpoles in Florida: evidence of competition. Biological Conservation 123:433-441. United States Department of Agriculture. Natural Resources Conservation Service. 2007. Plants Database. http://plants.usda.gov/java/profile?symbol=EICR. United States Department of Agriculture. Soil Conservation Service. Soil Survey of Mayagüez Area Western Puerto Rico. December 1975. United States Department of Agriculture. Puerto Rican Karst – A Vital Resource. Forest Service. Gen. Tech. Report WO-65. August 2001. U.S. Fish and Wildlife Service. 1992. Recovery Plan for the Puerto Rican crested toad (Peltophryne lemur). Atlanta, Georgia. 19 pp. Wassersug, R. 1971. On the Comparative Palatability of Some Dry-Season Tadpoles from Costa Rica. American Midland Naturalist, 86(1): 101-109.

33

Tables Table 1. General characteristics of five ponds under investigation.

1

2

3

4

5

Ponds in

Bo. San José

Bo. Cocos

Bo. Cocos

Bo. Cocos

Las Talas

Quebradillas

(Martínez)

(Los Jacintos)

(Los González)

(Rodríguez)

Built

Callejon de Doña

Hoyo Brujo

Papo

Dec 18, 1943

Rosa

Geographic

18.28163N

18.28060N

18.28134N

18.28341N

18.27554N

Coordinates

66.55152W

66.55106W

66.54436W

66.54574W

66.57052W

Bufo lemur

1976

1974

1977

1976

Observations

1977

1975

1980

1977

1980

1977

1985

1978

1992

1980

WGS-84

1982 1983 (introduced)

Soil Type

Matanzas

Matanzas

Matanzas limestone

Limestone

Limestone

clay

limestone rock

rock

outcrop

outcrop

land complex

land complex

Grassland

Grassland

Grassland

Grassland

Forest

145

35

160

55

1000

Elevation (m)

85

95

95

85

113

Type of

Cement pond

Cement pond

Cement pond

Cement pond

Cement pond

6x7

4.5 x 5

7 x 15.6

9.2 x 10.5

5x9

Land Use 2001

Distance to River (m)

Breeding Pond Size (m)

34

Figures

WS Study ponds

1

3

4

Weather station (WR)

2 5

WS

Figure 1. Location of five ponds under investigation in the municipality of Quebradillas, Puerto Rico northwest karst zone (image on left: Ikonos 2004 state plane 1983, image on right: USDA 2001). The four ponds to the east are historic Bufo lemur breeding locations, the single pond located to the west is considered a future captive bred toad release site.

2a.

2b.

Figures 2a and 2b. State of pond 1 (located in Bo. San José, Quebradillas) in October 2005 compared to March 2007.

36

3a.

3b.

Figures 3a and 3b. State of pond 2 (located in Bo. Cocos, Quebradillas) in March 2005 compared to January 2007.

37

4a.

4b.

Figures 4a and 4b. State of pond 3 (located in Bo. Cocos, Quebradillas) in March 2005 compared to October 2006.

38

5a.

5b.

Figures 5a and 5b. State of pond 4 (located in Bo. Cocos, Quebradillas) in September 2005 compared to December 2006.

39

Figure 6. State of pond 5 (located in Las Talas, eastern Quebradillas) in August 2005. Photo by Ricardo Colón.

40

Eleutherodactylus antillensis

Eleutherodactylus coqui 1.00

0.75

0.50

0.25

0.00 1.00

2.00

3.00

Site

4.00

5.00

1.00

Average Calling Activity



1.00

Eleutherodactylus cochranae

0.75

0.50

0.25

0.75

0.50

0.25

0.00

0.00 1.00

2.00

3.00

Site

4.00

5.00

1.00

2.00

3.00

4.00

5.00

Site

Figure 7. Average calling activity per species at the five ponds in the municipality of Quebradillas (Site 1 – 4: January 2006 – December 2006, Site 5: January 2006 – July 2006). 41

Urban Forest Pond Agriculture Ocean Grassland Study Sites

Figures 8a and 8b. Comparison of land use changes in the municipality of Quebradillas, Puerto Rico, from 1963-2001 as viewed through satellite images and analyzed in ArcView 3.2 by Rosanne Medina (2004, unpublished report).

42

Appendix A Kruskal-Wallis and All-Pairwise Comparison Tests E. antillensis

E. coqui

Kruskal-Wallis One-Way Nonparametric AOV Mean Sample Variable Rank Size Site1 2884.5 1346 Site2 2994.6 1406 Site3 3137.0 1206 Site4 3018.5 1216 Site5 3017.3 838 Total 3006.5 6012


Kruskal-Wallis Statistic 35.5256 P-Value, Using Chi-Squared Approximation 0.0000


Parametric AOV Applied to Ranks Source DF SS MS F P Between 4 4.102E+07 1.025E+07 8.93 0.0000 Within 6007 6.899E+09 1148541 Total 6011 6.940E+09

Parametric AOV Applied to Ranks Source DF SS MS Between 4 2.393E+09 5.982E+08 Within 6007 1.026E+10 1708764 Total 6011 1.265E+10

Total number of values that were tied 6012 Max. diff. allowed between ties 0.00001 Cases Included 6012 Missing Cases 1018


Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Site1 Site2 Site3 Site4 Site1 2884.5 Site2 2994.6 110.0 Site3 3137.0 252.4* 142.4 Site4 3018.5 133.9 23.9 118.5 Site5 3017.3 132.7 22.7 119.7 1.2

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Site1 Site2 Site3 Site4 Site1 2125.4 Site2 3591.6 1466.1* Site3 2574.6 449.2* 1016.9* Site4 3141.0 1015.6* 450.5* 566.4* Site5 3866.4 1741.0* 274.8* 1291.8* 725.4*

Alpha 0.05 Critical Z Value 2.807


43

F P 350 0.0045

E. cochranae

L. albilabris







F P 306 0.0038

F P 179 0.0019



Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Site1 Site2 Site3 Site4 Site1 2689.7 Site2 2689.4 0.3 Site3 3029.5 339.8* 340.0* Site4 3123.0 433.3* 433.6* 93.6 Site5 3845.2 1155.5* 1155.8* 815.8* 722.2*

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Site1 Site2 Site3 Site4 Site1 2106.0 Site2 3217.9 1111.9* Site3 3255.6 1149.5* 37.7 Site4 3212.4 1106.3* 5.5 43.2 Site5 3441.0 1335.0* 223.1* 185.4 228.7*



44

Kruskal-Wallis One-Way Nonparametric AOV Mean Sample Variable Rank Size site1 2956.3 1346 site2 2795.3 1406 site3 3000.4 1206 site4 3453.5 1216 site5 2801.8 838 Total 3006.5 6012

O. septentrionalis á á Kruskal-Wallis One-Way Nonparametric AOV Mean Sample Variable Rank Size Site1 2826.8 1346 Site2 3324.5 1406 Site3 2950.9 1206 Site4 2867.9 1216 Site5 3042.7 838 Total 3006.5 6012



Parametric AOV Applied to Ranks Source DF SS MS F Between 4 3.443E+08 8.607E+07 Within 6007 3.271E+09 544541 Total 6011 3.615E+09


B. marinus

P 158 0.0019



Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean site1 site2 site3 site4 site1 2956.3 site2 2795.3 161.0 site3 3000.4 44.1 205.1* site4 3453.5 497.2* 658.2* 453.1* site5 2801.8 154.5 6.5 198.6 651.7*

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Site1 Site2 Site3 Site4 Site1 2826.8 Site2 3324.5 497.7* Site3 2950.9 124.1 373.6* Site4 2867.9 41.1 456.7* 83.1 Site5 3042.7 215.9* 281.8* 91.8 174.9



45

á

Appendix B

Pond 1 Finca los Martínez Bo. San José Quebradillas Perimeter: 6m x 7m

Pond 2 Los Jacintos Bo. Cocos Quebradilla Perimeter: 4.5m x 5m

Pond # 3 Charca de los González Bo. Cocos Quebradilla Perimeter: 7m x 15.6m

Class

Order

Family

Genus

Species

Insecta

Coleoptera

Dytiscydae

Predacious diving beetle

1

Insecta

Coleoptera

Hydrophilidae

Water scavenger beetle

1 larva

Insecta

Odonata

Libellulidae

Gastropoda

Pulmonata

Physidae

Reptilia

Testudinata

Emydidae

Insecta

Hemiptera

Insecta

Tramea

Common Name

Quantity

Skimmer dragonfly

1

Physid snail

2

Red-eared slider

1

Pleidae

Backswimmer

1

Hemiptera

Corixidae

Water boatman

1

Insecta

Coleoptera

Hydrophilidae


Gastropoda

Pulmonata

Physidae

Physid snail

90

Amphibia

Anura

Hylidae

Cuban treefrog

8

Trachemys

Osteopilus

septentrionalis

1 larva

Insecta

Hemiptera

Belostomatidae

Boscii

Giant water bug

1

Insecta

Hemiptera

Macrovelidae

Mesovelia

Macrovelid shore bug

1

Insecta

Hemiptera

Gerridae

Water strider

2

Insecta

Odonata

Libellulidae

Skimmer dragonfly

1

Gastropoda

Pulmonata

Physidae

Physid snail

1

Gastropoda

Pulmonata

Ampullariidae

Osteichthyes

Microcyprini

Poeciliidae

Amphibia

Anura

Bufonidae

Perithermis

2

Bufo

46

marinus

Guppy

53

Marine toad

1

Pond # 4 Charca de los Rodríguez Bo. Cocos Quebradilla Perimeter: 9.2m x 10.5m

Pond # 5 Las Talas Quebrada El Gallo Bo. Las Talas Quebradillas Perimeter: 4.9m x 9m

Class

Order

Family

Genus

Insecta

Odonata

Libellulidae

Perithemis

Insecta

Hemiptera

Insecta

Species

Common Name

Quantity

Skimmers dragonfly

7

Belostomatidae

Giant water bug

11

Hemiptera

Gerridae

Water strider

1

Insecta

Hemiptera

Notonectidae

Backswimmer

17

Osteichthyes

Perciformes

Cichlidae

Tilapia

2

Osteichthyes

Microcyprini

Poeciliidae

Guppy

26

Amphibia

Anura

Bufonidae

Marine toad

8

Insecta

Coleoptera

Dytiscydae

Predacious diving beetle

6

Insecta

Coleoptera

Hydrophilidae


2

Insecta

Hemiptera

Notonectidae

Backswimmer

7

Insecta

Hemiptera

Corixidae

Water boatman

10

Insecta

Hemiptera

Gerridae

Water strider

1

Insecta

Odonata

Libellulidae

Tramea

skimmers dragonfly

25

Insecta

Odonata

Libellulidae

Perithemis

skimmers dragonfly

1

Insecta

Diptera

Stratiomyidae

soldier fly

3

Insecta

Diptera

Chironomidae

non-biting midge

1

Hirudinea

Rhynchobdellida

Glossiphoniidae

Leech

9

Gastropoda

Pulmonata

Physidae

Physid snails

40

Amphibia

Anura

Leptodactylidae

White-lipped frog

2

Oreochromis

Bufo

47

Helobdella

Leptodactilus

marinus

punctatolineata

albilabris

Chapter 2 Effect of Abiotic Variables on the Calling Activity of Amphibians at Bufo [Peltophryne] lemur Northern Breeding Sites

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ABSTRACT Recent amphibian population declines stress the urgency to establish methods and protocols to survey amphibians, and to document their distribution and activity patterns. Amphibian reproduction is constrained greatly by a combination of environmental variables. It is vital to understand how these variables affect amphibian activity particularly when considering environmental changes that may occur due to suggested climate change. The objectives of this study were to survey amphibians at four documented Puerto Rican crested toad breeding ponds in the northern municipality of Quebradillas and at a potential captive bred toad release site, and to investigate the association between calling response of each species detected and seasonal and daily weather changes. Six species of amphibians, including two exotics (Bufo marinus and Osteopilus septentrionalis) were detected over the 2006 survey period. Bufo lemur was not detected. Members of the Eleutherodactylus genus called frequently throughout the year, generally more so when humidity was higher. Leptodactylus albilabris were also active year round. Both exotic explosive breeders, Bufo marinus and Osteopilus septentrionalis, called less frequently but calling activity for each increased the day following main rain events. Calling activity of exotic species was otherwise divided spatially and temporally. The presence of these invasive species breeding after rain events at the northern Bufo lemur breeding ponds may have placed additional stress on the development of endemic species that once used these ponds during the same reproductive window.

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RESUMEN Los declives recientes en poblaciones de anfibios enfatizan la urgencia de establecer métodos y protocolos para el monitoreo de anfibios, y de documentar su distribución y patrón de actividad. La reproducción de los anfibios se rige por una combinación de variables ambientales. Es necesario entender como estas variables afectan a la actividad de los anfibios, particularmente al considerar los cambios ambientales que pueden surgir debido al calentamiento global. Los objetivos de este estudio fueron monitorear anfibios en cuatro charcas de reproducción tradicionales del sapo concho puertorriqueño y una charca considerada propicia para liberación de renacuajos de reproducción en cautiverio en el municipio de Quebradillas en el norte e investigar las asociaciones entre el canto de cada especie detectada y los cambios estacionales y diurnos. Seis especies de anfibios, incluyendo dos especies exóticas (Bufo marinus y Osteopilus septentrionalis) se documentaron durante el periodo de monitoreo de 2006. No se detectó al Bufo lemur. Los integrantes del género Eleutherodactylus cantaron frecuentemente todo el año, por lo general más en tiempo de humedad alta. Leptodactylus albilabris también estuvo activa todo el año. Las dos especies de reproducción explosiva, Bufo marinus y Osteopilus septentrionalis, cantaron con menor frecuencia, pero la actividad para cada especie aumento el día después de la lluvia. Los cantos de las especies exóticas se dividieron espacial y temporalmente. La actividad reproductiva de estas especies invasoras en las charcas antiguas de reproducción del sapo concho puertorriqueño, después de los eventos de lluvia, podría añadir estrés sobre el desarrollo de esta especie endémica, que también se reproducía durante la misma ventana temporal.

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INTRODUCTION

The Global Amphibian Assessment, carried out by the Declining Amphibian Population Task Force, estimates that a third of known amphibians are currently under threat (GAA 2006). This assessment lists habitat loss and destruction, pollution, disease, invasive species, and climate change among the most probable causes for amphibian population declines. In order to track these population changes it is crucial to establish methods and protocols to survey amphibians, establish species inventories, and document their distribution (Peterson and Dorcas 1994). Amphibian reproduction is constrained by environmental variables. The manner in which these variables trigger reproductive events is an important piece of information, particularly in light of suggested ongoing climate change. A range of biotic and abiotic variables is known to trigger anuran reproductive events. Studies and anecdotal evidence suggest precipitation, temperature, relative humidity, barometric pressure and lunar phase affect anuran activity, but further long term data needs to be gathered for a more thorough understanding of temporal windows for anuran reproduction (Brooke et al. 2000, Oseen and Wassersug 2002, Saenz 2006). Puerto Rico has experienced the loss of three species of Eleutherodactylus in the last 10 years and a decline in 7 other species, including Puerto Rico’s only endemic toad, the Puerto Rican crested toad, Bufo lemur (Burrowes et. al 2004). Studies by Burrowes et al. (2004) suggested warming trends over the last 30 years and prolonged drought have contributed to the decline of native species on the island. In addition, at least five exotic species have been introduced to the island over the last century and competition from these may add even further pressure to native anuran populations (Rivero 1998). Keeping track of the distribution and

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reproductive habits of native and introduced anuran populations in relation to weather variables is important in order to understand changes in either group and the effect one group might have on the other. This study focuses on the distribution and reproductive pattern of species of amphibian at historic Puerto Rican crested toad (Bufo [Peltophryne] lemur) breeding ponds. Puerto Rican crested toads are a cryptic species associated with karst formations and dependent on heavy rains (more than 2 inches over a 24 hour period) to fill temporary ponds for periods long enough to allow tadpole development (USFWS 1992). Anecdotal evidence (Miguel Canals personal communication) suggests these heavy rain events coupled with prolonged drops in barometric pressure (drops of 1/10 inHg) trigger toad reproductive events. Puerto Rican crested toads were first observed breeding at ponds in the municipality of Quebradillas, northwest Puerto Rico, in 1974 and were last observed at these sites in 1992. The objectives of the study were: 1) – to survey amphibians at four documented Puerto Rican crested toad breeding ponds in the northern municipality of Quebradillas and at a potential captive bred toad release site, 2) – to investigate the association between calling response of each species and seasonal environmental changes (i.e., temperature, relative humidity, rainfall, change in barometric pressure and lunar phase) at these sites, and 3) - to investigate the association between calling response of each species to daily weather changes.

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MATERIALS AND METHODS Study Area Automated data recorders were set up to record amphibian calls and weather parameters at five sites in the municipality of Quebradillas, northwest Puerto Rico (Figure 1). Four of the five sites are located adjacent to Bellaca creek where crested toads were last known to breed in the north, and the fifth site, located to the west of Quebradillas, is considered an area of interest to release captive bred toads.

Temperature, Rainfall, Relative Humidity and Barometric Pressure Hobo® Data Logging Rain Gauges were placed within the study area (approximately 1.17 km between rain gauges) (Figure 1). Only weeks surrounding heavy rain events over the year (over 25.4 mm/1 inch of rain over a 24 hour period) were examined in order to ensure the detection of crested toads. Temperature and relative humidity were recorded every 30 minutes by Hobo® Pro Series Weatherproof Loggers placed 2 m above ground at each pond. Plastic covers were used to camouflage the loggers and protect them from rain. Barometric pressure data was obtained from the Climatology Center at the University of Puerto Rico at Mayagüez, 40 km away from the study site (http://atmos.uprm.edu). Lunar phase activity was collected from U.S. Naval Observatory (http://aa.usno.navy.mil).

Anuran Vocalization Recordings Traditional survey methodology to conduct inventories and determine reproduction stages (visual counts, pittraps, call surveys, larval sampling, etc.) can be labor intensive and has been

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known to miss secretive, fossorial or deep water species (Peterson and Dorcas 1994). Call survey times outlined by the North American Amphibian Monitoring Program (NAAMP) have failed to detect some species (Bridges and Dorcas 2000, Corn et al. 2000), so the introduction of automated data recorders to monitor amphibian populations first reported by Peterson and Dorcas (1992) has made monitoring in tricky terrain, conditions and time frames a somewhat easier task. Therefore, to search for extant Puerto Rican crested toads, automated recording devices were used to record amphibian calling activity and weather conditions at five ponds in the northwest of Puerto Rico over the course of one year. The four historic ponds were monitored from January 6, 2006 to December 31, 2006. The fifth site was monitored from January 6 – June 2, 2006. Sony® Hi-MD froglogger systems (Sony® Hi-MD MZ-RH10 digital portable recorder, controller, waterproof case and cables) were chosen for this study based on their inconspicuous size and mid-range cost. Each logger is equipped with a high quality Sony® ECM-MS908C Stereo Condenser Microphone to ensure quality recording and minimize misidentification of species. Frogloggers were located within 5 meters of each pond with microphones set 1- 2 meters above ground and pointed towards the pond as recommended by Bridges and Dorcas (2000). Equipment was well hidden, chained to trees and camouflaged to prevent theft. Loggers were preprogrammed to record 14 seconds of sound activity every 30 minutes over a 24 hour period to ensure every species was detected, particularly the elusive Puerto Rican crested toad. Information from the loggers was downloaded weekly. At the laboratory individual calls were viewed as a spectrogram and identified to species using Raven Light, developed by the Cornell Ornithology Laboratory. Calls by species were categorized as present = 1 or absent = 0 with no distinction between a chorus and lone individuals. Differences in calling rates per

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species between rain events, days of rain event and weather variables were examined. Data sets were collected at 30 minute increments but not necessarily simultaneously at each pond, acoustical data “drifted” every hour, so data within +/- 15 minutes of each 30 minutes was assigned to the closest time set.

Statistical Analysis Daily calling activity was monitored during heavy rain events for one year (Figure 2), in an effort to detect rare species; however, only nocturnal amphibian calling activity was examined for this study. Statistical tests were carried out to determine differences in calling activity between rain events to see how calling activity varied throughout the year. Kruskal-Wallis analyses were used to test for no difference in calling activity between rain events, and then pairwise comparison tests checked which rain events were significantly different from each other (Statistics 8.0). The statistical hypothesis of no relationship between calling activity and each abiotic variable gathered daily at 2100 h (i.e., temperature, relative humidity, change in barometric pressure from one day to the next, percent moon illumination and total daily precipitation) was then analyzed with logistic regression using Minitab 15. The slope of the equation determines whether abiotic factors had a positive or negative predictive effect on calling activity. Saenz (2006) stated that the “logit illustrates the probability of calling when a weather parameter changes by one unit (i.e., a logit of 1.0 indicates no change in calling activity, whereas 1.5 indicates a 50% increase in calling activity)”. The effect of precipitation was best determined by considering calling activity three days prior to a rain event, the day it rained (day 4) and the following three days. Kruskal-Wallis was used to test the null hypothesis of no

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difference in calling activity over the seven day period and, then, pairwise comparisons were used to compare each rain day. As calls were recorded from 1800 – 0600 h, it was interesting to examine calling activity in response to daily weather patterns. To examine daily patterns further, logistic regression was used to test the hypothesis of no effect of daily weather variables on calling activity. A correlation was first carried out to determine any relationships above r2>0.5 between weather variables. As calling activity is not an independent event, a Markov autocorrelation model was included by adding calling activity the previous hour during analysis of nocturnal calling patterns. The final data set contained the following variables: event number (1-11), day number (1-7), calling activity per species (presence = 1, absence = 0), calling the previous hour, temperature (°C), relative humidity (%), total rainfall (mm), barometric pressure (kPa), and lunar illumination (%).

RESULTS From January 6, 2006 to December 31, 2006 three families of amphibians (Leptodactylidae, Bufonidae and Hylidae) were documented over eleven periods of heavy rain (two consecutives days of heavy rain were considered together during rain event #5). Four eleutherodactylids were recorded: Eleutherodactylus antillensis, E. coqui, E. cochranae, and Leptodactylus albilabris. The extensively introduced marine toad (Bufo marinus; Bufonidae) was detected as was the introduced Cuban treefrog (Osteopilus septentrionalis; Hylidae). Puerto Rico’s only endemic pond breeding Bufonid, the Puerto Rican crested toad, was not detected. Kruskal-Wallis analysis rejected the null hypothesis of no difference in calling activity between ponds for each species. Four of six species were documented at each pond. The 56

Antillean coqui (E. antillensis) called frequently at every pond: a difference was detected between pond 1 with the least activity and pond 3 with the most activity. Differences were detected for the common coqui (E. coqui) calling activity at all ponds: calling was highest at ponds 5 and lowest at pond 1. Calling activity for the whistling coqui (E. cochranae) was significantly higher at site 5 and the species was not detected at ponds 1 or 2. White-lipped frogs (L. albilabris) called at all ponds but significantly less at pond 1. Statistical analysis illustrated that marine toads calling most actively at pond 4, and were not active at pond 2. Cuban treefrogs were detected calling at all ponds, but most actively at pond 2. Figure 3 illustrates the calling activity of each species per pond. Table 1 illustrates dates the frogloggers were operational, total recordings per site and total days down over the period of analysis. Kruskal-Wallis results are included in Appendix A of Chapter 1.

Temperature, Relative Humidity, Precipitation, Barometric Pressure and Lunar Illumination Temperature does not fluctuate greatly in Puerto Rico. There are approximately two less hours of daylight in winter (approximate sunrise 0700 h and sunset 1800 h) than in summer (approximate sunrise 0600 h and sunset 1900 h). Climate data from Puerto Rico from 1955-1975 (SERCC 2007) indicate average temperatures were lowest in February (23.4 °C) and highest in September (26.4 °C) similar to temperatures recorded in Quebradillas during the 2006 study period (Figure 4). Daily highs were recorded at 1230 h (28.3 °C) slowly decreasing overnight to reach lows at 0600 h (21.3 °C). At 2100 h average temperature was lowest in February (21.9 °C) and highest in August (25.2 °C). Daily relative humidity was on average lowest at 1200 h (80.6%)

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and reached 99.8% at 0700 h Relative humidity was highest over the hot wet summer months (June, July and August) (Figure 5). Weather in Puerto Rico tends to be characterized by wet and dry seasons. Most precipitation in Quebradillas from 1955-2000 occurred between April-June and OctoberDecember (SERCC 2007) and the hurricane season is official from June 1st until November 30th. In 2006 more rain fell towards the beginning of the year (March-May) and less than average towards the end (Figure 6). Most precipitation in 2006 fell in March (16.6 cm), April (23.2 cm) and May (28.4 cm) for a total annual rainfall of 150.1 cm. On April 22nd, 16.5 cm of rain fell in one afternoon alone (Figure 7)! Drops in barometric pressure often associated with heavy rain events were of particular interest for this study but no evident drops in pressure associated with precipitation became apparent in 2006. However, low pressure can occur without rain and rain can occur without low pressure (Winter personal communication) The largest drops in barometric pressure from one day to the next (measured at 2100 h) occurred on March 7th (-0.31 kPa), April 1st (-0.24 kPa), and August 9th (-0.27 kPa). However, during the week of rain no obvious patterns were noted (Figures 8 and 9). During 2006 average barometric pressure was a little higher from June to September. Percent lunar illumination was considered a significant variable but its predictive effect was neutral (logit = 1.00) and will not be discussed any further.

Seasonal Calling Activity Kruskal-Wallis analyses rejected the null hypothesis of no difference between calling activity and rain event for each species. Calling activity for Antillean coquis was lower early in the year (January – March), calls peaked in late March (event #3) and continued at a steady rate 58

until the end of November (event #11). Common coqui calls peaked significantly mid season in May (events #5 and #6), and again in September and November (events #10 and #11). Whistling coqui calls varied greatly between rain events. There was no calling activity early in the year (event #1 or #2), calls peaked in March and remained strong until early June (event #6), then decreased and picked up again in November. Calling by White-lipped frogs was low in January (event #1), increased and reached a peak in March (event #2 and #3), and slowly decreased until to a low point in early June (event #7), and picking up again in August (event #8). Marine toads and Cuban treefrogs called less intensely and less frequently. Marine toads called most at the beginning of June (event #7) and in November (#11). The most significant change in Cuban treefrogs calling activity occurred between high activity in May (event #5) and low activity in January (event #1) June (event #7), and November (event #11). Figure 10 illustrates the calling activity of each species during each rain event and Appendix A includes Kruskal-Wallis results. Logistic regression examined the change in calling activity per species according to a unit change in abiotic variables (i.e., temperature, relative humidity, changes in barometric pressure, total precipitation and moon illumination). Results of logistic regression were not significant for Antillean coquis, common coquis or White-lipped frogs. Calling by whistling coquis was predicted by increasing relative humidity (z = 3.72, p = 0.000, logit 1.12) and decreased with precipitation (z = -1.39, p = 0.164, logit 0.99). Calling by marine toads seemed most associated with increased temperature (z = 2.37, p = 0.018, logit 1.29). Cuban treefrog calling activity increased slightly with total precipitation (z = 1.38, p = 0.168, logit 1.01) and calling decreased almost 100% with increasing barometric pressure (z = -4.58, p = 0.000, logit 0.00) (Table 2).

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Calling Activity during Rain Events Kruskal-Wallis analysis rejected the null hypothesis of no difference between calling activity during each day of the rain event for each species. Antillean coquis called frequently during each day of the rain event but all-pairwise comparison tests indicated a difference between days prior to rain (with less calling), the day it rained and the following day (with greatest calling). Calling for common coquis appeared to decrease most significantly two days following the rain compared to calling before and during the rain event. No significant differences were detected in calling activity for whistling coquis. White-lipped frogs increased calling activity the day before it rained and calling remained strong for three days post rainfall. Marine toad activity peaked the day after it rained, was still strong the following day (day 6) and returned to pre-rain calling activity three days after the rain. Cuban treefrogs showed a similar calling activity pattern with peak calling the day after the rain but decreased activity the following day (day 6). Figure 11 compares calling between rain days for each species and Figure 12 illustrates average precipitation over the week. Appendix B includes Kruskal-Wallis results.

Effect of Daily Weather Fluctuations on Calling Activity Most species called between 1800 – 0600 h in response to environmental variables and calling by conspecifics. Logistic regression results showed that calling the previous hour was the most significant predictor of calling activity for all species. In order to avoid eliminating variables that may have a predictive effect on calling, variables showing a predictive association p < 2.00 are discussed. Antillean coquis were detected calling most frequently in 85% of recordings. Logistic regression analysis indicated rising relative humidity (z = 11.26, p = 0.000,

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logit 1.06) barometric pressure (z = 4.04, p = 0.000, logit 2.43), and temperature (z = 1.73, p = 0.084, logit 1.04) were all associated with calling activity. Common coquis were detected over 63% of recordings and calling was most predicted by increasing temperature (z = 7.02, p = 0.000, logit 1.15) and relative humidity (z = 4.23, p = 0.000, logit 1.02). Increasing barometric pressure however had a negative effect on calling activity (z = -1.36, p = 0.173, logit 0.78). Whistling coquis were only detected on 11% of recordings. Calling was most predicted by a unit increase in temperature (z = 7.21, p = 0.000, logit 1.38), relative humidity (z = 2.98, p = 0.003, logit 1.04) and precipitation (z = 2.84, p = 0.004, logit 1.06). An increase in barometric pressure seemed to decrease calling activity by 49% (z = -1.68, p = 0.094, logit 0.51). White-lipped frogs called on 46.5% of recordings and were predicted to increase with rising barometric pressure (z = 4.98, p = 0.000, logit 2.09) and temperature (z = 3.08, p = 0.002, logit 1.05). Increasing relative humidity had a minor negative effect on calling activity of this species (z = -3.66, p = 0.000, logit 0.99). Of the two introduced species, marine toads were heard on 7.2% of recordings. Increasing relative humidity (z = 3.79, p = 0.000, logit 1.05) and barometric pressure (z = 2.14, p = 0.033, logit 2.05) predicted its increased calling activity. Increasing relative humidity (z = 4.94, p = 0.000, logit 1.06) followed by barometric pressure (z = 3.88, p = 0.000, logit 3.26) predicted calling activity by Cuban treefrogs and calling seemed to decrease with increasing temperature (z = -4.51, p = 0.000, logit 0.85). The results of the effect of daily weather fluctuations on calling activity of each species are outlined in Table 3.

DISCUSSION Previous studies have shown temperature and rainfall to have the most significant effect on amphibian calling (Oseen and Wassersug 2002, Saenz 2006), but many of these studies are 61

carried out in temperate zones with extreme temperature fluctuations which are not as restrictive in tropical areas. In the tropics amphibian reproduction may also be cued to other variables depending on the strategies and requirements of each species. How explosive breeders and prolonged breeders differ in their response to abiotic variables has been a point of some debate. Oseen and Wassersug (2002) suggest this uncertainty is due to short-term and intermittent data collection. Although this study was carried out for one year, only the weeks surrounding rain events were taken into consideration. So results are biased towards the activity of these species during rain events. The following section contains a general discussion on the calling activity of the native prolonged breeders. The main discussion, however, will focus on the reproductive activity of explosive breeders, both invasive anurans.

Native Species Logistic regression analysis was unable to demonstrate any significant association between seasonal weather conditions and calling activity for the three species most frequently detected in this study: Antillean coquis, common coquis and White-lipped frogs, possibly because these species called too frequently over the study period and the model could not discern the effect of any of the considered abiotic variables. These members of the genus Eleutherodactylus do not rely on a body of water for their young to develop. Eggs are deposited in closed areas, near to the ground and on vegetation (Joglar 1998), where they develop directly into juvenile froglets. Therefore, we would imagine that their reproductive activity would be less dependent on precipitation and more so on other environmental variables. Differences in calling activity between rain events throughout the year however provide some indication of environmental preferences.

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Joglar (1998) found gravid Antillean coqui females all year suggesting this species breeds all year, although more actively in some seasons than others. He suggested relative humidity is the most significant variable in reproductive activity of this species. Indeed Antillean coquis were detected throughout the study period but called more frequently after March, when temperatures started to rise along with relative humidity. Their calling activity during the week of rain indicated calling increased after the main rain event when humidity was higher. The results of logistic regression for daily calling patterns also indicated increasing relative humidity, temperature and barometric pressure predicted their calling activity. Common coquis also called less frequently at the beginning of our study, and picked up later in May when temperatures and relative humidity began to rise. Studies have determined common coquis breed all year but more actively during the wet season (Joglar 1998). Drewry and Rand (1983) also suggested activity reaches peak intensity over the most humid summer nights and decreases over the winter period. Over the week of rain, calling activity decreased slightly towards the end of the week (days 6 and 7). Logistic regression results of daily calling activity indicated a positive association between increasing relative humidity and temperature on calling activity. In general, Antillean coquis and common coquis called actively over this study indicating year round reproductive activity. The whistling coqui, a smaller, lowland dweller mostly found in dry forest (Rivero 1998) was detected much less frequently than the above mentioned species (on 10.8% of recordings). Statistical analysis did indicate an association between increased relative humidity and calling activity. Studies by Joglar (1998) found gravid females and egg clutches year round but calling activity during this study was most notable from March to June, and then decreased by the end of November (event #11). No significant differences in calling activity were detected between days

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during the week of rain. Possibly because this species was detected most prominently in a forested area (site 5) where shade and a variety of covered habitats maintain elevated humidity. White-lipped frogs were heard frequently across most sites (site 1 was poor in activity for all species) mostly as a single call earlier in the evening. Calls by this species peaked in March and August. White-lipped frogs do not rely directly on a body of water to deposit their eggs but rather build a foam nests near water where tadpoles develop for a few days until they are washed into the water by rain (Rivero 1998). This could explain why calling was strong across the week of rain, with slightly more calling on day 3, and on days 5 and 6. Results of daily calling activity suggest increased calling with warmer temperatures and rising barometric pressure and a slight decrease in calling with increasing humidity. White-lipped frogs call earlier in the evening when temperatures are higher and pressure is rising and less in the early morning when humidity is highest. They tend to stay closer to bodies of water and low to the ground where they do not suffer as quickly from dehydration and are therefore not as sensitive to humidity.

Introduced Species The need to understand the distribution and reproductive patterns of invasive species in Puerto Rico is equally as important as it is of endemics. Introduced anurans have been accused of supporting the decline of native anurans (GAA 2006, Lever 2001) but somehow manage to continue their expansion unchecked. Meshaka (2001) suggested part of the reason for the success of invasive species has been disinterest from scientists. These species usually adapt easily to living in human developed habitats, disperse easily, and are highly fecund (Meshaka 2005). Each pond breeding amphibian documented during this study has been studied extensively and is considered a threat to native fauna: Cuban treefrogs (Meshaka 2001), and marine toads (Lever

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2001). Their breeding activity is considered more thoroughly in this discussion as their presence and reproductive patterns may have contributed to the disappearance of the endemic toad Puerto Rican crested toad at the breeding ponds studied during this research. Marine toads and Cuban treefrogs called less intensely and frequently throughout the study period. However, each of these explosive species is considered highly fecund and any reproductive activity can result in over 8,000 eggs being laid by a female of either species. Interestingly, calling activity at the ponds appeared dominated by one or the other species: at site 2, where most Cuban treefrogs were documented calling, marine toads, although observed on field visits, were not detected calling. Marine toads, on the other hand, dominated pond 4 where few Cuban treefrogs were detected. Calling activity throughout the year also appeared divided between the species, when Cuban treefrogs called most actively marine toads appeared less active, and the opposite was also observed. Over the study period marine toads called most actively at the beginning and end of the hurricane season (June and November), and less frequently at the beginning of January – March and in late May. Rivero (1998) noted that this large toad reproduces usually at the beginning of the rainy season in permanent or temporary bodies of water. Marine toad must balance prey abundance with water loss. At the beginning of the wet season when humidity rises and prey abundance is still high, toads become most active (Lever 2001). Logistic regression results indicated increasing temperature best predicted marine toad calling. Temperatures over the year were highest from June to October as was relative humidity, coinciding with increased calling by marine toads. Cuban treefrogs called the least in January, June and November, and most in May and early June (events 5 and 6). Studies by Meshaka (2001) in the Everglades, stated Cuban treefrogs

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calling most often in association with rain and always during high humidity and warm temperature. The most significant calling event during this study occurred the week of event 5 at the beginning of May, which had the highest amount of rainfall during the study period (17.8 cm) and experienced a drop in barometric pressure. Anecdotal evidence suggests that many animals predict rapid drops in barometric pressure and react accordingly. Studies of breeding pond selection and movement patterns by Eastern Spadefoot toads (Scaphiopus holbrooki; Greenberg and Tanner 2004) suggest that interaction between rainfall and change in barometric pressure best predicted explosive breeding events. A study on blacktip shark behavior (Heupel and Simpendorfer 2003) describes how sharks predicted an oncoming storm and left the bay area for a week while habitat conditions were unfavorable. Miguel Canals (personal communication) also suggested the breeding activity of Puerto Rican crested toads in Guánica is triggered by low pressure events. No major tropical storms or hurricanes occurred in Puerto Rico in 2006. I tracked changes in barometric pressure and rainfall over 2006 and no significant trends in falling pressure and precipitation were detected. Nevertheless, on June 24 Puerto Rican crested toads deposited fourteen clutches of eggs at Guánica (Pacheco personal communication). Barometric pressure appeared to decrease by 0.237 kPa four days prior (June 20th) to this event but no heavy rain was observed in the north. Of the species detected in this study, marine toads and Cuban treefrogs would be most expected to respond to decreasing barometric pressure since they are both explosive breeders. However, no significant results were detected for marine toads. Cuban treefrogs did show an

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almost 100 % decrease in calling activity with rising barometric pressure in logistic regression results. Since both of these invasive anurans are explosive breeders we would expect them to increase their breeding activity on the day with heaviest rainfall or following day. In fact, calling activity during the week of rain was similar for both species. Calling increased on day 5 following rainfall and marine toads also called on day 6 (Figure 10). Canals (personal communication), manager of the Guánica State Forest has observed Puerto Rican crested toads and marine toads breeding in the same pond, suggesting that marine toads might compete with crested toads for access to refuges and food within the ponds. Evidence of similar spatial and temporal calling activity between both bufonids was also documented during a site visit in 1983 to breeding ponds in the north by Miller (1985), when marine toads called between 2000 and 2200 h and were followed by crested toads calling between 2200 and 0100 h Daily logistic regression results were also similar with an increase in relative humidity and barometric pressure, predicting calling activity for both invasive species. Meshaka (2001) noted general calling patterns for Cuban treefrogs usually began a few hours after sunset and continued for four to five more hours in the Florida Everglades. If eggs were laid though, he observed a peak in calling just before sunrise. Vargas (2006) observed calling events that began at 1800 h and reached maximum activity between 0300-0600 h Results of logistic regression in this study indicated an increase in temperature seemed to predict less calling activity for Cuban treefrogs. They appeared to be more active later into the night and early morning during this study as temperatures cooled slightly. Both marine toads and Cuban treefrogs use the artificial ponds previously occupied by the Puerto Rican crested toads in northern Puerto Rico. They appear to reproduce within the 67

same temporal window, and are both considered a threat to native biodiversity. In Australia marine toads are considered a real threat to biodiversity where this species has been implicated in the death of birds, fish, snakes, turtles and crocodiles (Hero and Stoneham 2005). They have been declared an animal pest in parts of Australia where programs have been started to control their spreading population (The Great Toad Muster 2006). Studies of Cuban treefrogs tadpoles are also implicated in the delayed growth and development of native larva in Florida (Smith 2005), and adults are also confirmed frog eaters (Meshaka 2001). In their native Cuba, the distribution of Cuban treefrogs is island-wide, including high elevation habitat (personal observation). In Puerto Rico, Cuban treefrogs were first documented in the northwest, but the list of confirmed sightings has expanded to San Juan, where they were spotted at the Botanical Garden (http://monitoreo.coquipr.com), to Boqueron and even to Vieques (Herrera personal communication). It may only be a matter of time until they reach higher elevation forested habitat where a number of vulnerable, endemic frogs are located . Joglar (2005) studied the interactions between Cuban treefrogs and common coquis. His results suggested that Cuban treefrogs compete with common coquis for daytime retreats, calling sites and food sources. Their continued expansion could cause a decline in populations of this native frog as well as others with similar ecological needs. In the case of the Puerto Rican crested toad, the arrival of these exotics at their breeding sites could have added stress on a population of individuals already stressed by habitat development. A program to control invasive species should be recommended for future monitoring and Puerto Rican crested toad reintroduction programs. The distribution of marine toads is already documented island-wide and steps have been taken to control their population at Puerto Rican crested toad release sites in the north at El Tallonal, and some removal has been carried out at

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ponds in the Guánica State Forest. So far no programs exist to control the population of Cuban treefrogs. Through his vast experience working with this species, Meshaka (2001) suggested that their colonization will continue on Puerto Rico due to the high rate of development and availability of useful habitats and appropriate weather conditions. He stated that although the reasons for its colonization success are its own, the reasons for its phenomenal success rest with us. It is up to us to study and understand how these organisms are now impacting Puerto Rico’s biodiversity and take action.

69

LITERATURE CITED Bridges, A.S. and M.E. Dorcas. 2000. Temporal variation in anuran calling behavior implications for surveys and monitoring programs. Copeia 2000:587-592. Brooke, P. N., A. A. Ross and L. Schwarzkopf. 2000. Environmental and social factors influence chorusing behaviour in a tropical frog: examining various temporal and spatial scales. Behavioral Ecology and Sociobiology 49:79-87. Burrowes, P. A., R. L. Joglar and D. E. Green. 2004. Potential Causes for Amphibian Declines in Puerto Rico. Herpetologica 60(2):141-154. Corn, P. S., E. Muths and W. Iko. 2000. A Comparison in Colorado of Three Methods to Monitor Breeding Amphibians. Northwestern Naturalist 81:22-30. Drewry, G. E. and A. S. Rand. 1983. Characteristics of an acoustic community: Puerto Rican frogs of the genus Eleutherodactylus. Copeia 1983:941-953. Global Amphibian Assessment. 2007. Declining Amphibian Population Task Force. http://www.globalamphibians.org/summary.htm. Greenberg, C. H. and G. W. Tanner. 2004. Breeding Pond Selection and Movement Patterns by Eastern Spade foot Toads (Scaphiopus holbrooki) in Relation to Weather and Edaphic Conditions. Journal of Herpetology 38(4):569-577. Hero. J. M. and M. Stoneham. 2005. Bufo marinus. In Amphibian Declines: The Conservation Status of United States Species, ed. M. Lannoo, 419-422. University of California Press, Los Angeles, CA. Heupel, M. R., C. A. Simpfendorfer, R. E. Hueter. 2003. Running before the storm: blacktip sharks respond to falling barometric pressure associated with Tropical Storm Gabrielle. Journal of Fish Biology 64(5):1357-1363. Joglar, R. L. 1998. Los coquies de Puerto Rico: su historia natural y conservación. Editorial de la Universidad de Puerto Rico, San Juan. _________. (ed.) 2005. Biodiversidad de Puerto Rico: Vertebrados terrestres y ecosistemas. Editorial del Instituto de Cultura Puertorriqueña. San Juan, Puerto Rico. Lever, C. 2001. The Marine Toad. The History and Ecology of a Successful Colonist. Westbury. Academic and Scientific Publishing, Otley, West Yorkshire.

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Meshaka, W. E., JR. 2001. The Cuban Treefrog in Florida – Life History of a Successful Colonizing Species. University Press of Florida, Gainesville, Florida. ________. 2005. Exotic Species. In Amphibian Declines: The Conservation Status of United States Species, ed. M.Lannoo, 271-274. University of California Press, Los Angeles, CA. Miller, T. 1985. Husbandry and Breeding of the Puerto Rican Toad (Peltophryne lemur) with comments on its natural history. Zoo Biology 4:281-286. Oseen K. L., R. J. Wassersug. 2002. Environmental Factors Influencing Calling in Simpatric Anurans, Oecologia 133(4):616-625 Peterson, C. R., and M. E. Dorcas. 1992. The use of automated data-acquisition techniques in monitoring amphibian and reptile populations. In McCullough, D. R., and Barrett, V., eds., 369-378. Wildlife 2001: Populations: London, Elsevier Applied Science. Peterson, C. R., and M. E. Dorcas. 1994. Automated data acquisition. In Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians, eds. Heyer, W. R., M. A. Donnelly, R. W. McDiarmid, L. C. Hayek and M. S. Foster, 47-57. Smithsonian Institution Press, Washington, D.C. Rivero, J. A. 1998. The Amphibians and Reptiles of Puerto Rico. Editorial de la Universidad de Puerto Rico, San Juan, Puerto Rico. 2nd edition. Saenz D., Lee Fitzgerald, Kirsten Baum, Richard Conner. 2006. Abiotic Correlates of Anuran Calling Phenology: The Importance of Rain, Temperature, and Season. Herpetological Monographs 20:64-82. Smith, K. G. 2005. Effects of Nonindigenous Tadpoles on Native Tadpoles in Florida: evidence of competition. Biological Conservation 123 (2005):433-441. Southeast Regional Climate Center (SERCC). 2007. http://www.sercc.com. The Great Toad Muster. 2006. Stop the Toad Foundation (Inc). www.stopthetoad.org.au. United States Department of Agriculture. Puerto Rican Karst – A Vital Resource. Forest Service. Gen. Tech. Report WO-65. August 2001. U.S. Fish and Wildlife Service. 1992. Recovery Plan for the Puerto Rican crested toad (Peltophryne lemur). Atlanta, Georgia. 19 pp.

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University of Puerto Rico at Mayagüez. 2007. Atmos Carib Research Center. http://atmos.uprm.edu/index.html U.S. Naval Observatory. 2007. Astronomical Applications Department. Sun and Moon Rise/Set http://aa.usno.navy.mil. Vargas-Salinas, F. 2006. Breeding Behavior and Colonization Success of the Cuban Treefrog Osteopilus septentrionalis. Herpetologica, 62(4):398-408.

72

Tables Table 1. List of rain events, total number of recordings and missed recordings at all sites over study period from January 6 to December 31, 2006. Event #

Event dates

Site 1

Site 2

Site 3

Site 4

Site 5

1 2 3 4 5 6 7 8 9 10 11

Jan 12-18 Mar 3-9 Mar 28-Apr 3 Apr 19-25 May 7-13 May 27-Jun 2 Jun 5-11 Aug 5-11 Sept 10-16 Sept 26- Oct 2 Nov 23-29

245 (91) 336 336 0 (336) 313 (23) 311 (25) 230 (106) 329 (7) 0 (336) 289 (47) 226 (110)

185 (151) 335 (1) 316 (20) 336 282 (54) 313 (23) 0 (336) 327 (9) 61 (275) 336 237 (99)

0 336 336 335 (1) 315 (21) 21 (315) 0 (336) 331 (5) 327 (9) 0 (336) 314 (22)

247 (89) 335 (1) 336 221 (115) 0 (336) 0 (336) 335 (1) 336 111 (225) 160 (176) 262 (74)

249 (87) 335 (1) 335 (1) 179 (157) 220 (116) 317 (19) Pulled* Pulled* Pulled* Pulled* Pulled*

Total Recordings

2615/3696 2728/3696 2315/3696 2343/3696 =70.8% =73.8% =62.6% =63.4%

* Pulled= Loggers were removed from the field due to equipment failure.

73

1635/3696 =44.2%

Table 2. Results of logistic regression analysis for abiotic variables at 2100 h (temperature, relative humidity, change in barometric pressure, percent moon illumination, and daily precipitation) versus calling activity during rain events over study period January 6 – December 31, 2006. E. antillensis Predictor Constant Temp C RH (%) Total Precip (mm) Change kPa Lunar Phase

Coef 6536.13 58.6159 -67.4988 0.150769 -1821.68 -8.21280

E. coqui Predictor Constant Temp C RH (%) Total Precip (mm) Change kPa Lunar Phase

Coef -2.92144 0.142990 0.0304846 -0.0051955 0.208795 -0.0076309

SE Coef 5.43991 0.214271 0.0404948 0.0128845 2.34642 0.0078360

Z -0.54 0.67 0.75 -0.40 0.09 -0.97

P 0.591 0.505 0.452 0.687 0.929 0.330

Odds Ratio

E. cochranae Predictor Constant Temp C RH (%) Total Precip (mm) Change kPa Lunar Phase

Coef -14.5429 0.122638 0.113599 -0.0124355 0.220768 -0.0000602

SE Coef 3.52154 0.113240 0.0305222 0.0089338 1.19991 0.0038366

Z -4.13 1.08 3.72 -1.39 0.18 -0.02

P 0.000 0.279 0.000 0.164 0.854 0.987

Odds Ratio

L. albilabris Predictor Constant Temp C RH (%) Total Precip (mm) Change kPa Lunar Phase

Coef 9.69379 -0.101160 -0.0349568 -0.0072979 -2.07851 -0.0076672

SE Coef 7.39527 0.268598 0.0625544 0.0145359 3.23367 0.0095185

Z 1.31 -0.38 -0.56 -0.50 -0.64 -0.81

P 0.190 0.706 0.576 0.616 0.520 0.421

Odds Ratio

B. marinus Predictor Constant Temp C RH (%) Total Precip (mm) Change kPa Lunar Phase

Coef -9.45850 0.258194 0.0243563 0.0052195 0.0772608 0.0040037

O. septentrionalis Predictor Coef Constant -0.629429 Temp C 0.0502950 RH (%) -0.0076515 Total Precip (mm) 0.0102642 Change kPa -5.56615 Lunar Phase -0.0005931

SE Coef 161051 1980.55 1893.14 26.1577 57264.8 281.573

Z 0.04 0.03 -0.04 0.01 -0.03 -0.03

SE Coef 2.96691 0.109011 0.0235435 0.0069988 1.18459 0.0037342

SE Coef 2.84240 0.108433 0.0223686 0.0074437 1.21534 0.0036453

P 0.968 0.976 0.972 0.995 0.975 0.977

Z -3.19 2.37 1.03 0.75 0.07 1.07

Z -0.22 0.46 -0.34 1.38 -4.58 -0.16

Odds Ratio 2.86122E+25 0.00 1.16 0.00 0.00

P 0.001 0.018 0.301 0.456 0.948 0.284

1.15 1.03 0.99 1.23 0.99

1.13 1.12 0.99 1.25 1.00

0.90 0.97 0.99 0.13 0.99

Odds Ratio 1.29 1.02 1.01 1.08 1.00

P Odds Ratio 0.825 0.643 1.05 0.732 0.99 0.168 1.01 0.000 0.00 0.871 1.00

Table 3. Results of logistic regression for abiotic variables (temperature, relative humidity, barometric pressure, precipitation and percent moon illumination) versus calling activity every 30 minutes (1800-0600 h) during rain events over study period January 6 – December 31, 2006. *Lag = calling the previous hour. E. antillensis Predictor Coef Constant -98.4277 Temp C 0.0391898 RH (%) 0.0620068 Rain(mm) 0.0095187 AtmosKPa 0.887934 Lunar Phase -0.0002178 ANTI (lag)* 2.77018

E. coqui Predictor Constant Temp C RH (%) Rain(mm) AtmosKPa Lunar Phase COQUI (lag)*

Coef 18.6898 0.141131 0.0211283 0.0107841 -0.244548 0.0019356 3.05396

E. cochranae Predictor Coef Constant 54.9196 Temp C 0.324206 RH (%) 0.0385529 Rain(mm) 0.0573008 AtmosKPa -0.674606 Lunar Phase -0.0022394 COCH (lag)* 4.59267E+10

L. albilabris Predictor Coef Constant -76.6037 Temp C 0.0518707 RH (%) -0.0148980 Rain(mm) -0.0117626 AtmosKPa 0.737860 Lunar Phase -0.0020822 LEPTO (lag)* 1.59979

SE Coef 22.3935 0.0226940 0.0055091 0.0201682 0.219639 0.0011609 0.0960340

SE Coef 18.1863 0.0201164 0.0049948 0.0175263 0.179299 0.0008873 0.0710502

SE Coef 40.7164 0.0449843 0.0129252 0.0201422 0.402485 0.0019548 39133.9

SE Coef 15.0396 0.0168683 0.0040733 0.0178432 0.148288 0.0007217 0.0567717

Z -4.40 1.73 11.26 0.47 4.04 -0.19 28.85

Z 1.03 7.02 4.23 0.62 -1.36 2.18 42.98

P 0.000 0.084 0.000 0.637 0.000 0.851 0.000

Odds Ratio 1.04 1.06 1.01 2.43 1.00 15.96

P 0.304 0.000 0.000 0.538 0.173 0.029 0.000

1.15 1.02 1.01 0.78 1.00 21.20

Z 1.35 7.21 2.98 2.84 -1.68 -1.15 1173579.52

P 0.177 0.000 0.003 0.004 0.094 0.252 0.000

Z -5.09 3.08 -3.66 -0.66 4.98 -2.89 28.18

P 0.000 0.002 0.000 0.510 0.000 0.004 0.000

75

Odds Ratio

Odds Ratio 1.38 1.04 1.06 0.51 1.00 *

Odds Ratio 1.05 0.99 0.99 2.09 1.00 4.95

B. marinus Predictor Constant Temp C RH (%) Rain(mm) AtmosKPa Lunar Phase BUFO (lag)*

Coef -81.5340 -0.0048406 0.0443388 -0.0274931 0.715959 0.0041241 3.49814

SE Coef 33.8689 0.0386480 0.0117102 0.0566882 0.334902 0.0014767 0.125231

Z -2.41 -0.13 3.79 -0.48 2.14 2.79 27.93

P 0.016 0.900 0.000 0.628 0.033 0.005 0.000

O. septentrionalis Predictor Coef Constant -126.819 Temp C -0.162027 RH (%) 0.0574783 Rain(mm) -0.0196572 AtmosKPa 1.18174 Lunar Phase 0.0001183 OSTEO (lag)* 2.78275

SE Coef 30.8298 0.0359113 0.0116465 0.0415186 0.304590 0.0013634 0.115240

Z -4.11 -4.51 4.94 -0.47 3.88 0.09 24.15

P 0.000 0.000 0.000 0.636 0.000 0.931 0.000

76

Odds Ratio 1.00 1.05 0.97 2.05 1.00 33.05

Ratio 0.85 1.06 0.98 3.26 1.00 16.16

Figures

WS

1

Study Sites Weather Stations

4 3

5

2 WS

Figure 1. Location of five ponds under investigation in the municipality of Quebradillas, Puerto Rico, northwest karst zone (image on left: Ikonos 2004 state plane 1983, image on right: USDA 2001). The four ponds to the east are historic Bufo lemur breeding locations, the single pond located to the west is considered a future captive bred toad release site.

1 0.8 Anti

0.7

Coqui

0.6

Coch

0.5

Lepto

0.4

Bufo

0.3

Osteo

0.2 0.1 22:30

21:00

19:30

18:00

16:30

15:00

13:30

12:00

10:30

9:00

7:30

6:00

4:30

3:00

1:30

0 0:00


0.9

Hour of day

Figure 2. Illustration of average calling activity (1 = presence and 0 = absence) per species over the study period. Data include the 5 study sites over a 24 hour period. Anti = E. antillensis, Coqui = E. coqui, Coch = E. cochranae, Lepto = L. albilabris, Bufo = B. marinus, Osteo = O. septentrionalis.

Eleutherodactylus antillensis


1.00

0.75

0.50

0.25

0.00 1.00

2.00

3.00

4.00

5.00

Site

Eleutherodactylus coqui


1.00

0.75

0.50

0.25

0.00 1.00

2.00

3.00

4.00

5.00

Site

Eleutherodactylus cochranae


1.00

0.75

0.50

0.25

0.00 1.00

2.00

3.00

4.00

5.00

Site

Figure 3. Average calling activity per species at each of the five ponds over the study period. Ponds 1-4 were monitored from January 6 – December 31, 2006. Pond 5 was monitored from January 6 – June 2, 2006. 79

27.0

26.0

Average Temp (C)

25.0

24.0

23.0

22.0

21.0

20.0 Jan

Feb

Mar

Apr

May

Jun

mean 1955-1975

Jul

Aug

Sep

Oct

Nov

Dec

2006

Figure 4. Comparison of average temperature readings between Southeast Regional Climate Center (SERCC) from 1955 - 1975 from Quebradillas and average Hobo recordings taken at the study sites from January 6 - December 31, 2006.

80

27.0 26.0 25.0

90.00 24.0 85.00 23.0 80.00

o

95.00

Temperature ( C)

Relative Humidity (%)

100.00

22.0

75.00

21.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months Avg RH (%)

Avg Temp °C

Figure 5. Average temperature and relative humidity readings from Hobos placed at study sites 1 - 4 in Quebradillas from January 6 - December 31, 2006.

81

300

Monthly Average Precipitation (mm)

250

200

150

100

50

0 Jan

Feb

Mar

Apr

May

Jun

Mean 1955-2000

Jul

Aug

Sep

Oct

Nov

Dec

2006

Figure 6. Comparison of average monthly precipitation between data collected from Southeast Regional Climate Center 1955-2000 (from Quebradillas) and that collected by rain gauges at the study site from January 6 – December 31, 2006.

82

104

180

120 103

100 80

102.5

60 40

102

20

Total daily precipitation (mm)

9/ 3/ 06 10 /3 /0 6 11 /2 /0 6 12 /2 /0 6

7/ 5/ 06 8/ 4/ 06

5/ 6/ 06 6/ 5/ 06

101.5

3/ 7/ 06 4/ 6/ 06

0

kPa at 2100 hrs

Figure 7. Comparison of total precipitation (mm) to barometric pressure cycles (kPa) from January 6 - December 31, 2006.

.

kPa at 2100 hrs

103.5

140

1/ 6/ 06 2/ 5/ 06

Precipitation (mm)

160

103.6

160

103.4

140

103.2

120

103

100

102.8

80

102.6

60

102.4 102.2

40

102

20

Total daily precipitation (mm)

11/27/2006

10/1/2006

9/16/2006

8/5/2006

6/6/2006

5/29/2006

5/10/2006

4/23/2006

4/2/2006

0 3/9/2006

101.8

kPa at 2100 hrs

Figure 8. Comparison of precipitation and drop in barometric pressure over 11 weeks of rain during study period from January 6 - December 31, 2006.

84

Precipitation (mm)

180

1/12/2006

kPa at 2100 hrs

103.8

103.7 103.6 103.5 Event 1 Event 2 Event 3 Event 4 Event 5 Event 6 Event 7 Event 8 Event 9 Event 10 Event 11

103.4 103.3

kPa at 2100 hrs

103.2 103.1 103 102.9 102.8 102.7 102.6 102.5 102.4 102.3 102.2 102.1 102 1

2

3

4

5

6

7

Day of Rain

Figure 9. Comparison of changes in barometric pressure for week of rain over eleven rains events during study in Quebradillas in 2006.

Figure 10. Average amphibian calling activity during each rainfall event over study period in 2006: Event 1 = Jan 12 -18; Event 2 = Mar 3 – 9; Event 3 = Mar 28 - Apr 3; Event 4 = Apr 19 – 25; Event 5 = May 7 – 13; Event 6 = May 27 - Jun 2; Event 7 = Jun 5 – 11; Event 8 = Aug 5 – 11; Event 9 = Sept 10 – 16; Event 10 = Sept 26 – Oct 2; Event 11 = Nov 23 – 29.

Figure 11. Average amphibian calling activity during each day during the week of rain over study period in 2006: Day 1 – 3 were days before the main rain event, day 4 was the main day of rain, day 5 -7 were days following the day event.

87

Average Rainfall (mm)

1.2 1 0.8 0.6 0.4 0.2 0 1

2

3

4

5

6

7

Day of Rain Event

Figure 12. Average rainfall over seven days of rain event. Days 1-3 are days before the rain event. Day 4 is the day of main precipitation. Days 5-7 are the three days post rain.

88

Appendix A Kruskal-Wallis and All-Pairwise Comparison Tests: Rain Events E. antillensis

E. coqui

Kruskal-Wallis One-Way Nonparametric AOV Mean Sample Variable Rank Size Event1 2234.1 464 Event2 2454.2 874 Event3 3354.2 865 Event4 3234.4 550 Event5 3175.2 573 Event6 3097.1 499 Event7 3042.4 289 Event8 2998.8 680 Event9 3010.3 275 Event10 3246.9 412 Event11 3322.6 531 Total 3006.5 6012








Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Event1 Event2 Event3 Event4 Event5 Event6 Event1 2234.1 Event2 2454.2 220.1 Event3 3354.2 1120.2* 900.0* Event4 3234.4 1000.3* 780.2* 119.8 Event5 3175.2 941.1* 721.0* 179.0 59.2 Event6 3097.1 863.0* 642.9* 257.2 137.4 78.2 Event7 3042.4 808.4* 588.2* 311.8 192.0 132.8 54.6 Event8 2998.8 764.7* 544.6* 355.5* 235.7 176.5 98.3 Event9 3010.3 776.3* 556.1* 343.9 224.1 164.9 86.7 Event10 3246.9 1012.8* 792.7* 107.3 12.5 71.7 149.9 Event11 3322.6 1088.6* 868.4* 31.6 88.2 147.4 225.6 Variable Mean Event7 Event8 Event9 Event10 Event7 3042.4 Event8 2998.8 43.7 Event9 3010.3 32.1 11.6 Event10 3246.9 204.5 248.2 236.6 Event11 3322.6 280.2 323.9 312.3 75.7

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Event1 Event2 Event3 Event4 Event5 Event6 Event1 2841.2 Event2 2607.6 233.6 Event3 2842.1 0.9 234.5 Event4 2904.2 62.9 296.5 62.0 Event5 3288.6 447.4* 681.0* 446.5* 384.5* Event6 3201.8 360.6 594.2* 359.7* 297.7 86.8 Event7 2536.5 304.8 71.1 305.6 367.7 752.1* 665.4* Event8 3069.8 228.6 462.2* 227.7 165.7 218.8 132.0 Event9 3024.4 183.2 416.8* 182.3 120.2 264.2 177.4 Event10 3417.1 575.8* 809.5* 575.0* 512.9* 128.5 215.2 Event11 3540.1 698.8* 932.5* 698.0* 635.9* 251.5 338.2 Variable Mean Event7 Event8 Event9 Event10 Event7 2536.5 Event8 3069.8 533.3* Event9 3024.4 487.9* 45.4 Event10 3417.1 880.6* 347.3 392.7 Event11 3540.1 1003.6* 470.3* 515.7* 123.0



E. cochranae

L. albilabris









Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Event1 Event2 Event3 Event4 Event5 Event6 Event1 2683.0 Event2 2693.3 10.3 Event3 3291.2 608.2* 597.8* Event4 3065.6 382.6* 372.3* 225.6 Event5 3186.6 503.6* 493.3* 104.5 121.0 Event6 3273.4 590.4* 580.0* 17.8 207.8 86.7 Event7 2849.4 166.4 156.1 441.7* 216.2 337.2 423.9 Event8 3014.5 331.5 321.2* 276.6 51.0 172.1 258.8 Event9 2759.5 76.5 66.2 531.6* 306.1 427.1* 513.8* Event10 2814.3 131.3 121.0 476.8* 251.3 372.3* 459.0* Event11 3186.8 503.8* 493.5* 104.3 121.2 0.2 86.5 Variable Mean Event7 Event8 Event9 Event10 Event7 2849.4 Event8 3014.5 165.1 Event9 2759.5 89.9 255.0 Event10 2814.3 35.1 200.2 54.8 Event11 3186.8 337.4 172.3 427.3 372.5

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Event1 Event2 Event3 Event4 Event1 2527.9 Event2 3248.6 720.6* Event3 3512.4 984.4* 263.8 Event4 3143.8 615.9* 104.8 368.6* Event5 2851.3 323.4 397.3* 661.1* 292.5 Event6 2571.8 43.9 676.7* 940.5* 571.9* Event7 2252.9 275.1 995.7* 1259.5* 890.9* Event8 3190.6 662.6* 58.0 321.8* 46.8 Event9 3007.2 479.2* 241.4 505.2* 136.6 Event10 3147.5 619.5* 101.1 364.9* 3.7 Event11 2700.6 172.6 548.0* 811.8* 443.2* Variable Mean Event7 Event8 Event9 Event10 Event7 2252.9 Event8 3190.6 937.7* Event9 3007.2 754.3* 183.4 Event10 3147.5 894.6* 43.1 140.3 Event11 2700.6 447.7* 490.0* 306.6 446.9*



90

Event5

Event6

279.5 598.4* 319.0 339.3* 618.7* 155.8 435.3* 296.2 575.6* 150.7 128.7

B. marinus

O. septentrionalis






Parametric AOV Applied to Ranks Source DF SS MS F P Between 10 9.317E+07 9316865 14.3 0.0000 Within 6001 3.898E+09 649531 Total 6011 3.991E+09



Kruskal-Wallis All-Pairwise Comparisons Test


Variable Mean Event1 2791.0 Event2 3045.5 Event3 2839.7 Event4 3042.4 Event5 2985.1 Event6 2899.4 Event7 3321.5 Event8 3069.5 Event9 3031.5 Event10 2922.3 Event11 3289.2 Variable Mean Event7 3321.5 Event8 3069.5 Event9 3031.5 Event10 2922.3 Event11 3289.2

Event1 Event2 Event3 Event4 Event5 254.5 48.7 205.9 251.4 3.1 194.1 60.4 108.4 146.1 530.5* 276.0 278.5 24.0 240.5 14.0 131.3 123.2 498.2* 243.7 Event7 Event8

202.8 145.5 59.8 481.8* 229.8 191.8 82.7 449.5* Event9

57.3 143.0 85.7 279.1 336.4 27.1 84.4 10.9 46.4 120.1 62.8 246.8 304.1 Event10

Event6

422.0 170.1 132.0 22.9 389.7*

252.0 290.0 38.0 399.1 147.2 109.1 32.3 219.7 257.7 366.8


Variable Mean Event1 2824.8 Event2 3041.6 Event3 2985.4 Event4 3067.1 Event5 3238.6 Event6 3158.1 Event7 2787.3 Event8 2961.0 Event9 2908.6 Event10 3080.2 Event11 2857.1 Variable Mean Event7 2787.3 Event8 2961.0 Event9 2908.6 Event10 3080.2 Event11 2857.1

Event1 Event2 Event3 Event4 Event5 216.8 160.6 242.3 413.8* 333.3 37.5 136.2 83.8 255.4 32.3 Event7

173.7 121.3 52.4 292.9 119.2 69.8 103.9


91

56.2 25.5 197.0 116.4 254.3 80.6 133.0 38.6 184.6 Event8

81.7 253.2 71.5 172.6 91.0 80.6 198.1 279.8 451.3* 24.4 106.1 277.6 76.8 158.5 330.0 94.8 13.1 158.4 128.4 210.0 381.6* Event9 Event10

171.6 51.5 223.2

Event6

370.8 197.1 249.5 77.8 301.0

Appendix B Kruskal-Wallis and All-Pairwise Comparison Tests: Days of Rain Event E. antillensis

E. coqui

Kruskal-Wallis One-Way Nonparametric AOV Mean Sample Variable Rank Size Day1 2850.4 875 Day2 2923.3 865 Day3 3024.4 824 Day4 3156.2 875 Day5 3180.9 888 Day6 2992.8 852 Day7 2910.0 833 Total 3006.5 6012








Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Day1 Day2 Day3 Day4 Day5 Day6 Day1 2850.4 Day2 2923.3 72.9 Day3 3024.4 174.0 101.1 Day4 3156.2 305.8* 232.9 31.8 Day5 3180.9 330.5* 257.6* 156.5 24.7 Day6 2992.8 142.4 69.5 31.6 163.4 188.1 Day7 2910.0 59.6 13.3 114.4 246.2 270.9* 82.8

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Day1 Day2 Day3 Day4 Day5 Day6 Day1 2997.6 Day2 3029.8 32.2 Day3 3169.0 171.5 139.2 Day4 3152.1 154.6 122.4 16.9 Day5 3108.7 111.2 78.9 60.3 43.4 Day6 2872.1 125.5 157.7 296.9* 280.1* 236.7 Day7 2706.5 291.0* 323.3* 462.5* 445.6* 402.2* 165.5



92

E. cochranae

L. albilabris





Parametric AOV Applied to Ranks Source DF SS MS F P Between 6 2.624E+07 4373092 5.06 0.0000 Within 6005 5.191E+09 864431 Total 6011 5.217E+09






Variable Mean Day1 Day2 Day3 Day4 Day5 Day6 Day1 2964.7 Day2 3065.3 100.6 Day3 3109.8 145.1 44.6 Day4 3002.5 37.8 62.8 107.3 Day5 3035.1 70.3 30.2 74.8 32.6 Day6 2979.4 14.7 85.9 130.5 23.1 55.7 Day7 2888.7 76.0 176.6 221.1 113.8 146.4 90.7

Variable Mean Day1 Day2 Day3 Day4 Day5 Day6 Day1 2844.8 Day2 2841.7 3.1 Day3 3107.4 262.6* 265.7* Day4 2971.9 127.1 130.2 135.5 Day5 3195.6 350.9* 354.0* 88.3 223.8 Day6 3153.3 308.6* 311.7* 46.0 181.5 42.3 Day7 2932.4 87.6 90.7 175.0 39.5 263.3* 221.0



93

B. marinus

O. septentrionalis









Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Day1 Day2 Day3 Day4 Day5 Day6 Day1 2863.1 Day2 2930.0 66.9 Day3 2893.1 30.0 36.9 Day4 3014.3 151.2 84.3 121.2 Day5 3281.8 418.7* 351.8* 388.7* 267.5* Day6 3179.1 316.0* 249.1 286.0* 164.8 102.7 Day7 2870.4 7.2 59.6 22.8 143.9 411.5* 308.7*

Kruskal-Wallis All-Pairwise Comparisons Test Variable Mean Day1 Day2 Day3 Day4 Day5 Day6 Day1 2849.0 Day2 2964.6 115.6 Day3 2894.2 45.2 70.4 Day4 3058.5 209.6 93.9 164.3 Day5 3318.3 469.3* 353.7* 424.1* 259.8* Day6 3062.9 213.9 98.3 168.7 4.4 255.4* Day7 2882.0 33.0 82.6 12.2 176.5 436.3* 180.9



94