spatial ecology, habitat preference, and habitat

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i

SPATIAL ECOLOGY, HABITAT PREFERENCE, AND HABITAT MANAGEMENT OF THE EASTERN MASSASAUGA, Sistrurus c. catenatus IN A NEW YORK WEAKLY-MINEROTROPHIC PEATLAND

Glenn Johnson A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy Degree

State University of New York College of Environmental Science and Forestry Syracuse, New York December 1995

Approved: Faculty of Environmental and Forest Biology

Major Professor

Chair, Examining

Faculty Chairman

Dean, Instruction and Graduate Studies

ii TABLE OF CONTENTS Page TABLE OF CONTENTS..........................................i LIST OF TABLES...........................................iii LIST OF FIGURES..........................................vii LIST OF APPENDICES......................................viii ACKNOWLEDGEMENTS..........................................ix ABSTRACT.................................................xvi PREFACE..................................................xix CHAPTER 1. GENERAL INTRODUCTION............................1 DISTRIBUTION AND STATUS General Distribution and Status.......................2 New York Distribution and Status......................6 GENERAL BIOLOGY...........................................12 GENERAL THEME AND DISSERTATION OBJECTIVES.................17 CHAPTER 2. SPATIAL ECOLOGY OF THE EASTERN MASSASAUGA RATTLESNAKE IN A NEW YORK STATE WEAKLY-MINEROTROPHIC PEATLAND.............................................19 INTRODUCTION..............................................19 STUDY AREA................................................20 MATERIALS AND METHODS.....................................24 Field and Telemetric Methods.........................24 Analytical Methods...................................25 RESULTS...................................................28 DISCUSSION................................................35 CHAPTER 3. HABITAT UTILIZATION BY THE EASTERN MASSASAUGA (SISTRURUS C. CATENATUS) IN A NEW YORK WEAKLYMINEROTROPHIC PEATLAND...............................46 INTRODUCTION..............................................46 METHODS...................................................48 Study Area...........................................48 Field and Telemetric Methods.........................50 Statistical Analysis.................................54 RESULTS...................................................57 DISCUSSION................................................74

iii

CHAPTER 4. HABITAT MANAGEMENT FOR THE EASTERN MASSASAUGA IN A NEW YORK WEAKLY-MINEROTROPHIC PEATLAND: THE EFFECTS OF CUTTING, BURNING AND HERBICIDES ON VEGETATION AND SMALL MAMMAL ABUNDANCE................81 INTRODUCTION..............................................81 MATERIALS AND METHODS.....................................82 Study Area...........................................82 Experimental Treatments..............................84 Analytical Methods...................................90 RESULTS...................................................93 DISCUSSION...............................................113 CHAPTER 5. SYNTHESIS AND CONCLUSIONS.....................125 CHAPTER 6. ASPECTS OF THE NATURAL HISTORY OF EASTERN MASSASAUGAS IN A NEW YORK WEAKLY-MINEROTROPHIC PEATLAND ...........................................135 LITERATURE CITED.........................................161 APPENDICES...............................................179 VITA.....................................................222

iv LIST OF TABLES Table

Page

1.1. Status of the eastern massasauga, Sistrurus c. catenatus, across its range as of June 1995...........5 2.1. Movement parameters for all radio-tracked Sistrurus c. catenatus over the period 1989-1992 in Cicero Swamp Wildlife Management Area.............30 2.2. Area (ha) of minimum convex polygon and harmonic mean activity ranges and time series analysis for individuals tracked greater than 90 days for Sistrurus c. catenatus at Cicero Swamp Wildlife Management Area. Time series activity range computed by summing successive seasonal 100% convex polygons and subtracting areas of overlap. Sum of seasonal home range/total range given in percent..............................................31 2.3. Means (and Standard Errors) of movement and activity measures for male, nongravid female, and gravid female Sistrurus c. catenatus, as well as the total data set (all classes combined) in CSWMA monitored for a minimum of 95 days. Different letters in a column indicate significant differences from one-way ANOVA (P = 0.05) with LSD tests............................................. ..33 2.4. Means of movement and activity measures for Sistrurus c. catenatus, in three locations across its range (western Pennsylvania - Reinert and Kodrich 1982; Bruce Peninsula - Weatherhead and Prior 1992; Cicero Swamp - this study)........... ...42 3.1. Description of structural variables measured at snake and random locations in "Burn" and "Swamp" habitat types in Cicero Swamp Wildlife Management Area. Those marked with an * were measured in the "Burn" habitat only, while those marked with a # were measured in the "Swamp" habitat only...................................... ..53 3.2. Mean (+ S.E.) of habitat variables measured at random and snake locations in the "Burn" habitat in Cicero Swamp Wildlife Management Area. Variables defined in Table 3.1........... ....58

v

Page 3.3. Total canonical discriminant structure coefficients for habitat variables measured in the "Burn" habitat at Cicero Swamp Wildlife Management Area. Variables defined in Table 3.1.....60 3.4. Classification results of Sistrurus c. catenatus discriminant function models in two habitat types at the Cicero Swamp Wildlife Mangement Area..........63 3.5. Classification results of Sistrurus c. catenatus discriminant function models using jacknife crossvalidation in two habitat types at the Cicero Swamp Wildlife Mangement Area.................64 3.6. Logistic regression models for eastern massasauga categories and random sites in swamp forest and transitional peatland ("Burn Area") habitat in Cicero Swamp Wildlife Management Area. Variable mnemonics defined in Table 3.1.......................65 3.7. Mean (+ S.E.) of habitat variables measures at random and snake locations in the "Swamp" habitat in Cicero Swamp Wildlife Management Area. Variables defined in Table 3.1.......................68 3.8. Total canonical discriminant structure coefficients for habitat variables measured in the "Swamp" habitat at Cicero Swamp Wildlife Management Area. Variables defined in Table 3.1......70 3.9. Mean (+ S.E.) snake body temperature (0C) and ratio of snake to air temperature from A)emergence until mean date of parturition and from B) mean date of parturition unti arrival at hibernation site for male, nongravid female, and gravid female eastern massasaugas in Cicero Swamp Wildlife Management Area. Different letters in a column indicate significant differences from ANOVA (alpha = 0.05)with Tukey HSD tests............................73

vi Page 4.1. Summary statistics of woody shrub and tree sapling stems > 10 cm in height and < 5 cm dgl) variables in Burn Area plots (n=24) prior to treatment (1990)..94 4.2. Summary statistics for canopy (> 5.0 cm dbh) tree species in Burn Area plots (n=24) prior to treatment (1990).....................................95 4.3. P-values for t-tests comparing treatments within years (alpha = 0.01) for response variables..........99 4.4. P-values of repeated measures ANOVA orthoganal polynomial contrasts for response variables. (alpha = 0.01)......................................100 4.5. Summary of mammalian herbivore browsing on woody stems in cut only (n=40) and cut and burned(n=15) 1 m2 plots in Cicero Swamp Wildlife Management Area in 1991.............................................102 4.6

P-values of ANOVA main effect of year for response variables within each treatment(alpha = 0.01).......106

4.7. P-values of the main effect contrasts of cut only vs cut and burn treatments and fencing vs no fencing treatments and interaction contrast within years for response variables.................107 4.8. Mean + S.E. (coefficient of variation) shrub seedling/stump sprout density1 (stems/m2), live woody stem basal area (m2ha-1) and percent mortality2 for three herbicide treatments, one mechanical treatment and control in experimental plots (each treatment replicated 4 times) in shrub fen habitat at Cicero Swamp in 1993. All measurements taken in central 1 m2 subplot of each 25 m2 experimental plot. Treatments defined below3 and in text. Means with same letter in a row are not significantly different (ÿ = 0.01, df = 15)........109 4.9. Summary of small mammal captures in treated (TRT - cutting and burning) and nontreated (NoTRT) areas in the transitional peatland habitat in Cicero Swamp over the period 1991 - 1993........112

vii

Page 6.1. Summary of captures, recaptures, numbers marked, and catch per unit effort of eastern massasaugas in Cicero Swamp Wildlife Management Area over the period 1980 - 1992..................................140 6.2. Dates and temperatures of emergence and onset of overwintering, and length of active season for radio-marked Sistrurus c. catenatus Cicero Swamp Wildlife Management Area............................143 6.3. Summary of eastern massasauga observations in Bergen Swamp by G. Johnson. Blood samples were obtained from all snakes listed in the table........154

viii LIST OF FIGURES Figure Page 1.1. Range map of Sistrurus catenatus showing subspecies and an intergrade between S. c. catenatus and S. c. termeginus. (Redrawn from Conant and Collins 1992)..............................3 1.2

Extant, historic, and purported eastern massasauga populations or sightings in New York State.................................................8

2.1

Location of Cicero Swamp Wildlife Management Area in New York State...............................21

2.2

Activity ranges (100% minimum convex polygons) of male snake 1.3 in 1989, 1990 and 1991 in Cicero Swamp Wildlife Management Area................36

2.3

Activity centers (50% minimum convex polygons) of male snake 1.3 in 1989, 1990 and 1991 in Cicero Swamp Wildlife Management Area................37

3.1

Two function plot of canonical axis 1 vs. canonical axis 2 from "Burn Area" habitat analysis.............................................62

3.2

Two function plot of canonical axis 1 vs. canonical axis 2 from swamp habitat analysis.........71

4.1

Arrangement and design of treatment plots in "Burn Area" habitat in Cicero Swamp Wildlife Management Area......................................85

4.2

Shrub stem density, basal area, and height and importance values of three most numerous shrub taxa and a combination of other woody shrub/ sapling taxa in cut only and cut followed by burning treatments in "Burn Area" habitat in Cicero Swamp Wildlife Management Area over the period 1991-1993.....................................96

4.3

Shrub stem density, basal area, and height and importance values of three most numerous shrub taxa and a combination of other woody shrub/ sapling taxa in four treatment types in "Burn Area" habitat in Cicero Swamp Wildlife Management Area in 1992 and 1993...............................104

ix LIST OF APPENDICES Page Appendix 1. Activity ranges of individual Sistrurus c. catenatus over the period 1989-1992 on the Cicero Swamp Wildlife Mangement Area, Cicero, New York...... ......................179 Appendix 2. Means and standard errors of vegetation variables and Importance values from experimental plots (n = 16) for cut only and cut and burn treatments..................201 Appendix 3. Means and standard errors of vegetation variables and Importance values from experimental plots (n=8) for the treatments a) cut only (CNF), b) cut only with herbivore exclosures (CF), c) cut and burn (BNF), and d) cut and burn with herbivore exclosures (BF) for the years 1992 and 1993..202 Appendix 4. Summary of vital statistics of all massasaugas captured at CSWMA over the period 1988-1993, exclusive of newborns (which were not marked).................................... .203

x ACKNOWLEDGEMENTS

Due to the somewhat extravagent nature of this project, I have the delightful task of acknowledging the efforts of numerous individuals and organizations. First of all, I would like to acknowledge the input, guidance, and friendship of two people who most significantly affected this work: Alvin (Commander) Breisch of The NYS Department of Environmental Conservation and my major professor, Dr. Donald Leopold. Al, in his own peculiar way, harrassed me to finish the damn thing, perhaps more than any other individual. Without his support, this project would have been absolutely nowhere. Don has been the ideal major professor. He alternately left me alone and kicked me in the butt as needed. His incredible store of knowledge of plant ecology and wetland ecosystems and his professional manner have been a continued inspiration. Although he may not know it, Dr. Howard Reinert also has played a significant role in this piece of work. Aside from serving on my committee from as far away as Pennsylvania, Howard has inspired me with his knowledge (especially of the biology of snakes), scientific professionalism, and writings over the years. I wish to thank my other committee members, Dr. William Shields, Dr. Robert Burgess, Dr. Maurice Alexander, Dr. Russ Briggs (Chair) and Dr. Reed Hainesworth who served on my canidacy exam committee. Each field season since 1988, one or several people contributed substantially to that years' effort, either on a paid or volunteer basis. I would like to thank these folks individually (and chronologically): 1988 - Mark (Mory) Morrison, Michael Ingraldi, and Todd Sinander; 1989 - Russ Baker and Ed Burns; 1990 - Mike Keefe, Mike Ingraldi, and Kathy Anderson; 1991 - Todd Wills, Doug ("I'm lost in the swamp") Hampton and Mike Keefe; 1992 - Kevin Brewer, Elizabeth Balko, Molly Connerton, Mike Rudolf, and Jennifer O'Reilly as well as Todd Wills again; 1993 - Molly Connerton and Sandie Doran. Paul Hess was there several years in a row. Most of these folks were residents at SUNY-CESF at one time or another. I'd like to single out Todd Wills and Molly Connerton for their efforts over several years; they volunteered numerous times and have become great friends. Other people have contributed time and effort to various field activities associated with this project, and I thank them here: Dan Gefell, Bill Halpin, Rachel Jankowitz, Bill Round, Mary Stebbins, Robert McNamara, Greg Smith and interns from Beaver Lake Nature Center, Bill Borgstead, Andy Metz, Barbara and Charlie Grunden, Larry Layne, Kelly Austin, Dave Collins, Sandy Muller, William Seybold, Robert

xi Fewster, Rob Barber, Heidi Kopf, Mary Beth Kolozsvary, Michele Hirth, Chris Ricciardi, John McNair, Daniel Hayes, students in Dr. Robert Chambers Wildlife Ecology Class in 1990, members of the 1991 ESF Woodsman Team (i.e. Regina Piccinini, Michelle Tackley, Debbie Cappuccitti, Monique Laufs, Chris LaRolla, Greg Comatas, Michael Huneke, and Robert Fewster), members of Gamma Delta Theta (the CESF sorority), Burnet Park Zoo Chapter of the Explorer's Club, Liverpool High School Environmental Group, and, especially, Rocky, Dewitt, and the rest of the boys from the Georgetown Correctional Facility (Swamp Habitat Improvement Team), who did the bulk of the cutting. Many professionals aided me in a variety of ways. Steve Stehman gave me a course in analysis of variance in three short meetings. Joe Bopp, Dave Steadman, and Paul Steblein of the New York State Museum Biological Survey were instrumental in our small mammal surveys from 1989-1993 (especially Joe!). Mike Kenny did an internship with the NYSDEC on massasaugas in Cicero in 1987 and he shared much valuable information with me. Karen Gaines and Pat Carragher conducted bird surveys for one full year. I thank Cheryl LeBlanc for her input, knowledge of Cicero Swamp, and for the memorable trail that will forever bear her name. Farmer/state trooper Mark Polchipek helped with snake locations and kept a careful watch on part of Cicero Swamp (he lives there). Dr. John Howard provided mammal traps and sensible conversation regarding swamp spraying issues. Special thanks to the late David Armstrong for several years of friendship and some of the best photography I have ever seen. Jim, Betsy, Mary, and other staff in Moon Library were always there to help with reference material or to forgive a fine. Drs. Larry Abrahamson and Chris Nowak helped substantially with the herbicide work. The late Carl Palm smoothed out permits across state lines (I sure miss him). Dave Collins, formerly of the Burnet Park Zoo, provided drift fences, sound advice, and companionship on field trips; Dr. Peter Rosenbaum from Oswego State filled a similar role when Dave left town. Thanks also to folks at the Endangered Species Unit - Peter Nye, Jim Eckler, Mark King, and, especially, Mike Kallaji. John Proud, Ward Dukelow, and Ernie Penoyer from Region 7 DEC were also helpful by providing permits, maps and other information about Cicero Swamp, and, most importantly, boots for the inmates. John Ozard and Scott Crocoll from the Habitat Inventory Unit of the DEC provided the global positioning system and came out to gather Cicero locational data with me. John Behler and Bob Cook from the New York Zoological Society provided information and a demonstration about drawing blood from a snake. Dr. Dick Bothner came along on a few trips to Bergen Swamp and was most enlightening (I

xii wish I met him earlier). George Snyder, former CESF photographer, was often there when I needed him (thanks George). Barbara Kermeen from AVM Instrument Company and Fred Anderka from Holohil Systems were very helpful with telemetry equipment. Jim Halligan provided access to forestry measuring tools and connected me with the Woodsman Team. Master of the Microtools Ed Mulligan made a special needle to implant transmitter antennas and kept my hygrothermograph calibrated. And lastly, I'd like to give a special nod to Don and Greg. I have benefitted by the advice and knowledge of several snake biologists and herpetologists including Dr. William Brown, Dr. Rich Seigal, Dr. William Maple, Dr. Steven Secor, Dr. Dick Bothner, John Behler, Kent Prior, Andy Holycross, Tom Johnson, and Bob Johnson. I would like thank many folks, current and former, at the Burnet Park Zoo who supported this project in several ways: Ken Reininger, Don Moore, Barbara Pickard, Dave Collins, Bob Cunningham (past president of the Upstate Herpetological Society), Dave Shubert, Frank Panero, Alan Baker, Dave Raboy, Dr. Anne Baker, and, most of all, Dr. Carolee Wallace, who performed all the implants with remarkable skill. I would also like to thank the members of the Bergen Swamp Preservation Society for permission to access their land and other assistance on this project, particularly Pat Martin and Patty Kowsky. To my friends and fellow graduate students, thanks for providing the discussions and other good times: Bruce Schulte, Michelle Hirth, Hope Malcolm, Liz Balko, Dale Garner, Kent Gustafson, Mike Kenny, Bill "Monolung" Seybold, Cecily Costello, Pradeep Hirethota, Kelly Austin, Jon Kennan, Steve Roberts, Steve Craycroft, Pete Feigley, Dave Hagen, Sandy Bonnanao, Lisa St. Hillaire, Anne Johnson (these last three helped with some tricky plant identification), Irene Mackun, JoAnne Oliver, Win Everham, Joe Cornell, Greg McGee, Peter Smalledge, Chris Nowak, Andy Molloy, Marcelo del Puerto, Rachel Mazur, Sheila Sleggs, Teresa Doherty, Kithsiri Ranawana, Rich Ruby, Margaret Pike, Ingrid Kaatz, Katrina Galactos, Dick McDonald, Dave Slomczynski, Suni Edson, Aimee Delach, Rob Barber, others I've unfortunately left out, and the Grand Curator of the Roosevelt Wildlife Collection, Ron Giegerich. Anthony Cognato and Dr. Scott Rogers spent way too much of their time helping me with the intracacies of molecular biology techniques. Michael Ingraldi helped develop the logistic regression models and Brian Underwood, Lixing Sun, Besh Dhamala, Robert Danehy, and Larry Layne were very helpful with statistical applications. Chris Millard provided tactical support and x bar. Jocelyn Aycrigg really, really,

xiii really helped me out with the use of EasyCADD and digitizing maps. One aspect of this project depended on locating rattlesnakes in a variety of locations across their range (no simple task) and many people deserve thanks for their help in this regard. First, to Kent Prior from Ontario, with whom I first discussed conservation genetics and tardigrade biology and to whom I continue to discuss conservation of massasaugas, I owe a debt of gratitude. He also has an vast store of knowledge of Ontario microbreweries! Other folks who assisted with this part of the study, by state or province, were: Ontario - Doug Sweiger and Kersten Hedgecock (Bruce Peninsula), Michele Villeneuve (Georgian Bay Islands National Park), Paul Pratt, Karen Cedar and Jo Barten (Ojibway Prairie); Pennsylvania Dave Johnson (Jennings Environmental Center), Bill Allen, Steve Harwig and Ned Weston (other PA sites); Ohio - Dr. Ralph Gibson, Jennifer Windus, Dennis Case, Doug Wynn, Bob Thobobbin, Guy Denny, Greg Colwell, and the indominatable Terry Jawarski from Cedar Bog; Indiana - Sherman Minton and Alan Resetar (Chicago Field Museum); Illinois - Tom Anton, Dr. Steve Barton, Ellin Beltz, Ken Mierzwa, and David and Pricilla Suarez (for use of their home); and Michigan Teresa Moran, and Dr. Craig Weatherbee. I also wish to thank Bob Johnson from the Metro Toronto Zoo, not only for blood samples, but for a crackerjack job with the International Massasauga Conference in 1992! Funding for various aspects of this project were provided by the American Wildlife Research Foundation, the Endangered Species Unit of the New York State Department of Environmental Conservation, the Central New York Wildfowlers, the Alexander Wetlands Grant, the Society for the Study of Amphibians and Reptiles Grants-in-Aid of Research, the Wilford Dence Award, the Upstate Herpetological Association, the Chicago Herpetological Society, Parks Canada, Burnet Park Zoo Chapter of AAZK, Friends of the Burnet Park Zoo and the Research Foundation of the SUNY College of Environmental Science and Forestry. I would like to dedicate this dissertation to the massasaugas of Cicero Swamp for providing me with an education and to three people not mentioned above; they have played a significant role in my career development, each in their own different ways. First is my Mom; she provided the initial spark that ignited my interest in the natural world. Next is Dr. Margaret (Meg) Stewart, who was the nearest person to a mentor I ever had. And lastly and mostly, to my wife Jocelyn.......to whom, well, I owe it all. In loving memory of Gris, Jerry Garcia, and most of all, my Dad, Herbert W. Johnson.

xiv ABSTRACT Johnson, Glenn. Spatial ecology, habitat preference, and habitat management of the eastern massasauga, Sistrurus c. catenatus, in a New York transition peatland. Typed and bound thesis, 222 pages, 26 tables, 12 figures, 1995. The eastern massasauga (Sistrurus c. catenatus) is listed as endangered in New York and is currently known from only two locations in the state. Characteristics of this species' spatial ecology and habitat preferences were investigated between 1989 and 1992 in the Cicero Swamp Wildlife Management Area (CSWMA), a large wetland complex near Syracuse, which contains a 37 ha transitional peatland suspected to be of critical importance to massasaugas. Radiotelemetered male (n = 11) and nongravid females (n = 2) left the transition peatland for nearby swamp forest soon after spring emergence while gravid females (n = 2) remained in the peatland until parturition. All telemetered snakes overwintered in the transition peatland. Of individuals tracked for the entire active seasons, gravid females moved significantly shorter distances per day ( = 7.1 m) and per season ( = 751.9 m) than either males (mean distance moved/day = 20.5 m; mean distance/season = 2940.2 m) or nongravid females (mean distance moved/day = 22.9 m; mean distance/season = 3712.2 m). Similarly, 100% minimum convex polygon (MCP) activity range estimates were smaller for gravid females ( = 2.0 ha) than either males ( = 27.8 ha) or nongravid females ( = 41.4 ha). A monthly time-series analysis of home range size of all individuals averaged 53.1% of the total 100% MCP activity range. Habitat preference models, partitioned by sex and reproductive condition, of S. c. catenatus were constructed using canonical discriminant and logistic regression analysis of 14 topographic and structural habitat variables measured at snake and random locations. Gravid females in the peatland showed the greatest selection within the array of available habitat and were distinguished by preference for areas with a lower stem density of shorter woody plants with a reduced canopy coverage. These sites had more vascular species than bryophytes in the ground layer than random or other snake group sites. Gravid females had significantly higher mean body temperatures and ratios of body/air temperatures than males or nongravid females suggesting that the selection of open habitats and limited mobility of gravid females is due to a need to maintain high body temperatures for embryo development. In swamp forest habitat, massasauga locations were characterized by lower canopy coverage and closer proximity to overstory trees and fallen logs than random sites, however these models were

xv less successful at predicting snake habitat than those for the peatland. Several management practices designed to benefit S. c. catenatus by increasing open habitat in the high shrub density transition peatland were implemented, including cutting, cutting followed by burning, herbivore exclusion following cutting and burning, and herbicide application. Sixteen 625 m2 plots were established in the transitional peatland in which all woody vegetation was cut, piled in plot center and burned. After the first year, shrub density, shrub basal area, and shrub height were greater in cut areas than areas that were cut and then burned. After three years, only shrub height continued to be greater in cut only areas. Stem density and importance value of shrub species other than the three dominant species were initially lower in burned areas than cut only areas but became higher by the third growing season. Both basal area and shrub height increase in both treatments at the same rate, while N. mucronata becomes less important in the plots over time. However, this species still maintains the highest importance value over the three year period. Browsing intensity in these experimental plots by mammalian herbivores was high, especially in burned areas. A second experiment to evaluate this browsing effect was conducted on eight plots treated as before except portions of the two treatments were fenced to exclude herbivores. Shrub height increased significantly in all treatment types over the two years monitored and, at the end of the first year, was consistently greater in cut only plots. At the end of the second year, this relationship only held in fenced vs. unfenced plots, indicating browsing had a significant effect on shrub height growth. The efficacy of the herbicide glyphosate was evaluated for one growing season and found to be very effective when applied as a broadcast foliar spray. Small mammal abundance and diversity in the transitional peatland were lower than in surrounding swamp forest. Over the three year monitoring period, small mammal abundance and diversity increased in the treated areas of the transitional peatland, however it is unclear if this is a permanent or transitory effect. The rate or incidence of massasauga use of these cleared areas is inconclusive, however nine out of 89 (10.1%) distinct aboveground radiolocations in the peatland from nine individual snakes tracked in 1991 occurred in or around cleared areas, which represents only 2.5% of the total peatland area, indicating a disproportionate use. Key words: eastern massasauga, Sistrusus c. catenatus, activity range, radiotelemetry, habitat selection, habitat management, peatlands, New York, reptiles

xvi Author's name in full: Glenn Johnson Candidate for the degree of: Doctor of Philosophy Major Professor: Donald J. Leopold Faculty: Environmental and Forest Biology State University of New York, College of Environmental Science and Forestry, Syracuse, New York

Signature of Major Professor ______________________________

xvii

PREFACE

This dissertation is composed of six chapters.

Chapter

1 is an introduction to the eastern massasauga (Sistrurus catenatus) , a discussion of its status, and a statement of the purpose of the dissertation.

A portion of this chapter

has been published in the proceedings of an international conference on the conservation of the massasauga held in 1992 (Johnson and Breisch 1993). written in journal format.

Chapters 2, 3 and 4 are

Chapter 2 concerns movement

patterns of eastern massasaugas and is written for the Journal of Herpetology.

Chapter 3 is the result of an

investigation of habitat preferences of eastern massasaugas and will be submitted to the journal Copeia.

Chapter 4

relates efforts involved with a habitat management strategy for the eastern massasauga and is being prepared for the Journal of Wildlife Management.

Chapter 5 is a summary and

synthesis of the dissertation.

Chapter 6 contains a variety

of natural history information, some of which may be submitted as notes to appropriate journals.

1

CHAPTER 1. The

GENERAL INTRODUCTION

massasauga, Sistrurus catenatus, is a medium-sized

(to 100.3 cm snout-to-vent (SVL) length) species of rattlesnake (Klauber 1972).

Massasaugas are included with

all other pitvipers in the subfamily Crotalinae, of the family Viperidae, a group containing three North American genera: Agkistrodon, Crotalus and Sistrurus (McDowell 1987). Of the three, Agkistrodon lacks a rattle on the tail. Sistrurus is distinguished from Crotalus by the presence of nine large plates dorsally on the head as opposed to numerous small scales between the supraocular scales (Gloyd 1940). The ground color of the dorsum of S. catenatus is gray to light brown with a mid-dorsal row of 21-50 dark brown to black blotches and three rows of smaller, similarly-colored blotches on each side.

The venter is black and often

mottled with yellow, cream, or white marks (Ernst and Barbour 1989).

S. catenatus is distinguished from its two

congeners (S. miliaris and S. ravus) by its larger size and the upper preocular scales touch the postnasal scales. There are three recognized subspecies of S. catenatus (Minton 1983).

The eastern race, S. c. catenatus

(Rafinesque 1818), usually has 25 midbody scale rows and very dark venter while the western massasauga, S. c. tergeminus (Say 1823, cited in Ernst 1992), typically has 24 midbody scale rows and a white or cream-colored venter with dark blotches.

A zone of intergradation between S. c.

2

tergeminus and S. c. catenatus is believed to exist in north central Missouri and possibly south central Iowa (Ernst 1992).

The desert massasauga, S. c. edwardsi (Baird and

Girard 1853), is the smallest (to 55.0 cm SVL) race, generally with 23 midbody scale rows and a white or cream-colored venter with only a few dark spots (Ernst 1992).

Distribution and Status General Distribution and Status The total range of all three subspecies of the massasauga (Fig. 1.1) includes southwest Ontario, central New York and northwestern Pennsylvania west to extreme southeast Minnesota, southern Wisconsin and eastern Iowa and southwest to eastern Colorado, western Texas, northern Mexico (Cuatro Cienegas Basin, Coahuila and near Aramberri, Nuevo Leon), southern New Mexico and southeastern Arizona (McCoy and Minckley 1969, Minckley and Rinne 1972, Minton 1983, Sinclair and Snell 1990, Hibbits 1991, Hammerson et al. 1991, Ernst and Barbour 1989, Ernst 1992). The eastern subspecies occurs in southwestern Ontario and in New York, Pennsylvania, Ohio, Michigan, Indiana, Illinois, Wisconsin, Minnesota, Iowa, and Missouri.

The

type locality is "prairies of the Upper Missouri", although no type specimen has ever been designated (Gloyd 1940). Recently, Beltz (1993) has reviewed the distribution and status of the eastern subspecies and provided a dot map

3

based upon currently available information.

Weller and

Oldham (1993) discuss its historic and current distribution in Canada.

It is clear that its distribution is highly

fragmented over much of its range (Bushey 1985, Beltz 1993, Casper 1993, Johnson and Figg 1993, Johnson and Breisch 1993, Reinert and Bushar 1993, Weller and Oldham 1993). S. c. catenatus is designated as endangered and therefore protected by state law, in five of the states in which it exists; Indiana lists it as "threatened", but gives no legal protection (Table 1.1).

In May 1990, the eastern

massasauga was added to list of species protected by the Ontario Game and Fish Act (Ontario Regulation 263/90) and in April 1991 it was declared a threatened species by the Committee on the Status of Endangered Wildlife in Canada (Weller and Oldham 1993).

Its status is generally listed as

special concern in the remaining states, a status designation that does not include legal protection, although its wetland habitats may be protected by law.

The species

is also listed as Endangered in Arizona and Colorado (Levell 1995). Since 1978, S. catenatus has been a Category 2 candidate for listing on the national level in the United States (Johnson and Menzies 1993).

This designation means

the species has been proposed for addition to the Endangered or Threatened list, but, from the standpoint of the U.S Fish and Wildlife Service (USFWS), information is lacking for a determination.

However, the Society for the Study of

4

Amphibians and Reptiles declared in 1976 that the eastern race was threatened with extinction on over 75% of its range (Ashton 1976).

At an international symposium on the

conservation of the eastern massasauga held in May of 1992 in Toronto, the consensus reached among experts is that many, if not most, populations have been significantly reduced and recovery and/or habitat protection programs need to be established (Johnson and Menzies 1993).

Since that

time, monies from the USFWS have been expended for survey work completed in Illinois (Beltz 1992) and continuing in Wisconsin, Michigan, and Ohio (J. Windus, pers. commun.; J. Legge, pers. commun.).

New York Distribution and Status The earliest scientific writing that mentions the eastern massasauga in New York State is by DeKay (1842) and he considered it extralimital in the state.

Since that

time, this snake has been reported from at least five discrete locations in the western half of the state. Currently, the eastern massasauga is known conclusively from only two locations in New York State (Fig. 1.2): Cicero Swamp Wildlife Management Area (CSWMA) in Onondaga County and Bergen-Byron Swamp in Genesee County. Perhaps the first description of the massasauga from New York was by Gebhard in 1853, who received a specimen taken from a white-cedar swamp, likely the Bergen Swamp, near the Town of Byron, Genesee County (Moesel 1918).

5

Moesel (1918) collected two specimens from the Bergen Swamp in June of 1917.

Wright (1919) reported massasaugas as "not

uncommon" from Bergen Swamp.

Numerous sightings still occur

from this area (Breisch 1984, Johnson 1990). Some of the earliest references to massasaugas at Cicero Swamp were reported by botanists (Wibbe 1883, Rust 1883).

An earlier report (Macauley 1829) refers to

rattlesnakes from a variety of locations in New York including several towns in Madison and Onondaga Counties. Macauley appears to be describing timber rattlesnakes, Crotalus horridus, however the above locations are more likely habitat for massasaugas.

Whiffen (1913) collected

three specimens from Cicero for the New York Zoological Society, when the swamp was much larger, extending eastward into Madison County and northwest into the Stanley J. Hamlin Wildlife Management Area, formerly known as Clay Marsh (Hopkins 1914, Bray 1930).

Massasaugas have not been

reported in recent times from Madison County, where most of the remaining wetlands have been converted to agriculture or are otherwise only marginally suitable for massasaugas. Despite some verbal reports from area residents and the occurrence of some potentially suitable habitat, massasaugas have not been found in the Stanley Hamlin Marsh (Johnson 1990).

Cicero Swamp still supports a population (Breisch

1984; Johnson 1988, 1990; Johnson and Breisch 1993) and has even received a degree of notoriety in the popular

6

literature (Kauffeld 1969), which is thought to have contributed to unregulated collecting in the 1970's. While bona fide museum specimens collected in New York exist only from these two extant sites (Reinert 1978), historic reports and anecdotal information indicate massasaugas may have occurred at several other locations (Fig. 1.2).

Moesel (1918) recorded a specimen from a site

referred to as Featherbed Swamp, near Spring Lake in Cayuga County.

Wright (1919) reported massasaugas from this area

also and states local farmers and members of the Botanical Section of the Rochester Academy of Science have also seen them.

While Featherbed Swamp appears on older Cayuga County

maps and has been described botanically (Wiegand and Eames 1925), recent visits to this area indicate extensive muck farming has completely altered the character of the site rendering it no longer suitable as massasauga habitat. Interviews with farmers in this region include no recollections or recent observations of massasaugas. There have been two unconfirmed sightings of massasaugas in the 1960's and 1970's at a peatland in the Town of Arcadia in Wayne County (Reixinger and Peterson 1982).

In addition, there are several reports of dogs from

this area believed to have died from snake envenomation. Repeated visits by the Endangered Species Unit of the New York State Department of Environmental Conservation (NYSDEC) and others in the 1980's have failed to validate these claims.

Similarly, annual site visits by this author

7

between 1990 and 1993 did not result in any massasauga observations.

Over the periods 1876 - 1900 and 1941 - 1943,

the site was extensively mined for peat (Rynearson 1985). These operations radically altered the character of the peatland and may have contributed to the extirpation of the purported massasauga population.

If the massasauga has been

extirpated from the site, it is unlikely they could reestablish without a translocation program. A report exists for a sighting from the mid-1960's in a sphagnum bog in the Town of Concord in Erie County.

A visit

by NYSDEC personnel in 1982 did not uncover any evidence of massasauga occupancy (Riexinger 1982).

Permission to visit

this site in 1992 was denied to this author by the current landowner.

A 1985 report of a massasauga came to the

NYSDEC from a commercial plant nursery near the Town of Falconer in Chautauqua County (A. Breisch, pers. commun.). In this instance, the description of the snake was reasonably conclusive, however it was killed and disposed of.

This nursery received regular shipments of peat moss

from Wainfleet Bog near Port Colburne, Ontario and it is possible the snake's origin was from such a shipment. Wainfleet Bog is a valid location for massasaugas in Canada (Weller and Parsons 1991).

A site visit was conducted to

the Falconer site in 1992 by the author and no suitable habitat was observed.

Finally, vague reports exist from a

large swamp east of Rochester and a planned landfill site in the Town of Riga, both in Monroe County.

Site visits to the

8

former area by this author and several visits to the latter by this author and individuals from the NYSDEC failed to uncover any massasaugas or suitable habitat. Extensive monitoring efforts for the massasauga were initiated by the NYSDEC in 1980 in CSWMA.

These

investigations suggested a dramatic decline based upon a 92.0% reduction in capture success over a three year study (Reixinger and Peterson 1982).

These results, coupled with

unregulated collecting and conclusive evidence of only one other extant population led to the 1983 addition of the massasauga to the New York State Endangered Species List.

General Biology The eastern massasauga is strongly associated with wetlands across its range (Wright 1941, Reinert and Kodrich 1982, Seigel 1986, Weatherhead and Prior 1992).

Several

wetland types are utilized, including fens, marshes and wet prairies.

Wetlands appear to be particularly important for

overwintering (Maple and Orr 1968; Hallock 1991; G. Johnson, pers. observ.).

Over much of its range, crayfish burrows

appear to be a primary overwintering situation (Maple and Orr 1968, Reinert 1978) although many snakes utilize other circumstances, especially where chimney-building crayfish (Cambarus sp.) do not occur (Hallock 1991, K. Prior, pers. commun.). The common condition in most overwintering sites is access to the unfrozen portion of the water table.

At

9

CSWMA, all radiotagged massasaugas monitored long enough to observe overwintering patterns hibernated under hummocks of sphagnum and shrubs.

Close examination of several of these

revealed water-filled spaces in the network of roots below the hummock.

Because the water table is very near the

surface and cavities under hummocks generally contain water, it is likely massasaugas remain in water through much of the overwintering period, as they have been observed to do in crayfish burrows (Reinert 1978).

It is probable that

massasaugas use hummocks as overwintering sites in Bergen Swamp as well.

I have observed them enter openings leading

below hummocks as an escape avenue.

Massasaugas do not

appear to aggregate like other species of crotaline snakes (Ernst and Barbour 1989).

White and Lasiewski (1971)

suggest that hibernating in groups conserves water by reducing the aggregate surface area.

Massasaugas avoid

water loss by hibernating in wet environments or, in arid parts of its range, by selecting burrows that provide a humid microclimate (Ernst 1992). Several studies have demonstrated a shift from lowland and wet prairie habitat to upland habitats during the active season (Conant 1938, Bielema 1973, Reinert and Kodrich 1982, Seigel 1986, Weatherhead and Prior 1992).

Most authors

believe this habitat shift is a response to increased food availability in upland areas, especially old fields and woodland edges.

Other workers (Wright 1941, Maple 1968)

detected no evidence of seasonal habitat shifts.

This

10

apparent lack of seasonal habitat shifts detected in some studies may be the result of the spatial scale of observation (e.g. where the degree of interspersion of wetlands and uplands is high) or where all the life requisites (overwintering and basking sites, food availability) are met in one community type.

Although no

snake has demonstrated territorial behavior (Gregory et al. 1987), many species appear to utilize a distinct activity range. The massasauga's diet consists primarily of endotherms, especially small mammals, although juveniles may accept small snakes (Keenlyne and Beer 1973, Seigel 1986).

Other

vertebrates, such as birds, lizards, and anuran amphibians have been reported, as well as incidental reports of insects, crayfish, and centipedes (Wright and Wright 1957, Klauber 1972, Froom 1972, Cook 1984, Hallock 1991, Ernst 1992).

Neonates have been observed using a caudal luring

strategy to attract frogs (Schuett et al. 1984).

Predators

include most carnivorous mammals within their range, as well as birds-of-prey and ophiophagous snakes (Ernst and Barbour 1989).

Chapman and Castro (1972) report a 41 cm (SVL)

desert massasauga taken by a loggerhead shrike (Lancus ludovicianus).

Due to their smaller size, neonates and

juveniles are probably susceptible to a wider array of predators. Studies have shown or suggested both annual and biennial reproductive patterns for massasaugas (Keenlyne

11

1978, Reinert 1981).

Lacking evidence to the contrary, it

is believed that massasaugas at CSWMA reproduce every two years.

Massasaugas give birth to live young, typically

between mid-August and mid-September (Reinert 1981, this study).

Brood size varies from three to 19 (Ernst and

Barbour 1989).

Mean brood sizes were 6.55 in Pennsylvania

(Reinert 1981), 6.35 in Missouri (Seigel 1986), 9.28 in CSWMA (Riexinger and Peterson 1982, G. Johnson 1988, 1990), and 11.66 in Ontario (Weller and Parsons 1991).

This

apparent geographic variation in reproductive effort and cycles suggests that management within a region or specific site be based upon reproductive characteristics of local populations, and not on published accounts from distant locales. Sexual maturity can be reached as early as 27 months (B. Johnson 1988), although this was with captive-raised animals.

Keenlyne (1978) studied a wild population in

Wisconsin and found that only seven percent of third-summer female individuals were non-reproductive.

Sex ratios in

most studies do not significantly differ from 1:1, although, depending on the habitat sampled and the time of year, one sex may be overrepresented due to differential habitat use by sex and reproductive condition. There are no published population size or density estimates from any wild deme of massasaugas; similarly, little is known about age-specific mortality rates.

Among

unpublished studies, Maple (1968) estimated a population in

12

northeastern Ohio to be 35 individuals (1.97 ha-1) using the Petersen index.

Reinert (1978) estimated a density of 0.59

to 3.78 individuals/ha-1 on a 8.1 ha site in western Pennsylvania.

Using bone growth rings from 323 collected

specimens from Buffalo County, Wisconsin, to estimate age, Keenlyne (1968) prepared life tables for male and female massasaugas.

In the first 5 years of life, mortality rates

were highest for 1st year animals (50%) and the mean expectation of further life for the 0-1 year class was 2.85 years.

This information, although difficult to obtain, is

necessary to model and predict future population sizes or extinction risks.

General Theme and Dissertation Objectives The impetus for this study was the formal recognition of the eastern massasauga as endangered in New York and the perceived need for a set of specific management guidelines and prescriptions designed to reduce the possibility of extirpation in CSWMA.

These guidelines should include both

population and habitat management strategies. The purpose of this research was to collect ecological information specific to the eastern massasauga in central New York and use this information to formulate a habitat management strategy and develop a plan to monitor its effectiveness.

Differences that might occur among

population subgroups defined by size, sex, and reproductive

13

condition will be incorporated into this plan.

The specific

objectives of this research are to (1; Chapter 2) describe the movements and activity ranges of S. c. catenatus in a transitional peatland and determine the influence of sex, reproductive condition, and season on these patterns, (2; Chapter 3) identify and quantify habitat structure variables used by S. c. catenatus in a transitional peatland and evaluate their utility in predictive models, and (3; Chapter 4) evaluate responses by vegetation and small mammals to treatments of cutting, burning, and glyphosphate application designed to create favorable early-successional conditions for S. c. catenatus

in a transitional peatland.

14

CHAPTER 2. SPATIAL ECOLOGY OF THE EASTERN MASSASAUGA RATTLESNAKE IN A NEW YORK STATE WEAKLY-MINEROTROPHIC PEATLAND

INTRODUCTION The spatial arrangement and movements of a mobile animal species clearly will reflect aspects of its behavior and ecology.

Detailed knowledge of this information is

critical to managers of wildlife resources, especially if the species in question is considered endangered, is regionally rare, or occurs on the periphery of its range in marginal habitat.

Differences in activity patterns may

exist between subgroups of a population, defined by size, age, sex, or reproductive condition, that will potentially impact conservation plans.

Additionally, there may exist

seasonal or yearly differences in movement patterns related to important life history events that need be determined. Recent advances in radio telemetry have made the study of the spatial ecology of generally secretive or inconspicuous organisms like snakes possible and evidence of these intrapopulational differences is becoming apparent in many species (Gregory et al. 1987, Reinert 1993).

The

eastern massasauga (Sistrurus c. catenatus), a wetland associate across its range (Wright 1941, Reinert and Kodrich 1982, Seigel 1986, Weatherhead and Prior 1992) is at its easternmost range extension in central New York.

Here, as

well as across its entire range, it is threatened with

15

extinction and exists as relatively small and isolated relict populations (Breisch 1984, Johnson and Breisch 1993). The specific objectives of this study were to determine the activity range and movement patterns of massasauga rattlesnakes by sex and reproductive condition in Cicero Swamp to 1) aid in the development of a management strategy for this species in New York and 2) compare with telemetric studies of this species in other habitat types and geographic locations (i.e. wet prairie in western Pennsylvania, Reinert and Kodrich 1982; coniferous forest/wetlands in Ontario, Weatherhead and Prior 1992).

STUDY AREA This study was conducted in Cicero Swamp, a 2024 ha wetland complex consisting of the 1754 ha Cicero Swamp Wildlife Management Area (CSWMA) and adjacent lands in Onondaga County, New York, approximately 15 km northeast of the city of Syracuse (Fig. 2-1).

CSWMA is publicly owned

and managed by the New York State Department of Environmental Conservation (NYSDEC) while most of the adjacent lands are private holdings.

The area lies between

75o59' and 76o05' West longitude and 43o07' and 43o10' North latitude at an average elevation of 122.0 m above sea level. Average annual temperature is 8.7oC, average January temperature is -4.7oC, average July temperature is 21.5oC and mean annual precipitation is 95.5 cm evenly distributed throughout the year (Hutton and Rice 1977).

The proximity

16

of the site to Lake Ontario and Oneida Lake exerts a moderating influence on regional climate, although snowfall is heavy, averaging between 254 and 305 cm annually (Hutton and Rice 1977). CSWMA is primarily a weakly-minerotrophic peatland complex consisting of mostly forested wetlands composed largely of red maple (Acer rubrum). Chase (1964) identifies four subcategories within this cover type based upon the relative abundance of tree species codominant or subdominant to red maple.

The most abundant, wettest type consists of

mostly A. rubrum (85% of tree basal area) with a smaller component of yellow birch (Betula alleghaniensis), American elm (Ulmus americana) and white ash (Fraxinus americana).

A

second community type is generally drier with A. rubrum and white pine (Pinus strobus) comprising 90% of the tree basal area.

A third type was considered by Chase to be the most

mesophytic and A. rubrum, eastern hemlock (Tsuga canadensis) and scattered black gum (Nyssa sylvatica) were the dominant trees. Within CSWMA, and near its western periphery, is a 37 ha transitional peatland, defined as intermediate between minerotrophic and ombrotrophic peatlands (Mitsch and Gosselink 1993).

This peatland resembles a shrub-carr and

appears especially important to the CSWMA massasauga population, primarily for overwintering and gestation. is the final cover type identified by Chase (1964).

This The

vegetation structure in this area is clearly distinct from

17

surrounding swamp habitat types, both on the ground and from examination of aerial photographs.

Its appearance is

primarily due to an intense fire that consumed up to one meter of peat while the area burned from June 1892 until the following January (LeBlanc and Leopold 1992).

This area

will be hereafter referred to as the "Burn Area".

The

microtopography generally consists of hummocks supporting trees and shrubs interspersed with hollows.

The ground

vegetation layer is composed of approximately 50% bryophytes, mostly Sphagnum spp. and Polytrichum spp. (LeBlanc and Leopold 1992).

The dominant shrub species are

mountain-holly, (Nemopanthus mucronata), highbush blueberry, (Vaccinium corymbosum), and black chokeberry, (Aronia melanocarpa), although leatherleaf, (Chamaedaphne calyculata), is abundant in areas of lower shrub growth. Tree species include black spruce (Picea mariana), Acer rubrum, tamarack (Larix laricina), and European white birch (Betula pendula).

A more complete description of the Burn

Area is found in LeBlanc (1988).

Nomenclature follows

Mitchell (1986) for all vascular plant species.

MATERIALS AND METHODS Field and Telemetric Methods Massasaugas were located by systematic searches in appropriate habitat based on historical occurrences at CSWMA over the period 1989-1993.

Each captured individual was

weighed, measured, and given an individual mark by clipping

18

the right or left half of one or two ventral scales. (Brown and Parker 1976a).

Snakes were sexed by probing the cloaca

for hemipene pockets (Schaefer 1934) and females snakes were palped to determine reproductive status. A subset of massasaugas captured at CSWMA was taken from the field for implantation of radiotransmitters.

All

implants were intraperitoneal using a modification of the methodology of Reinert and Cundall (1982).

The major

modifications were the use of the inhalent anesthetic methoxyflurane in place of halothane (Aird 1986) and the mode of delivery of the anesthetic.

Anesthesia was

administered via a plastic cone placed over one end of a clear plexiglass tube containing the snake and rates of delivery and relative proportion of the anesthetic and oxygen could be monitored and adjusted.

In 1989, AVM model

SM-1 transmitters fitted with Mallory HG625 or HG675 mercury batteries and 30-40 cm whip antennas were used.

Batteries

and antenna were affixed to the transmitter upon receipt and the package was potted with a 50:50 mixture of beeswax and paraffin (Reinert 1992).

These transmitters had a battery

life of approximately 160 days and maximum transmission distances of 800 m.

Beginning in 1990, an implantable

temperature-sensitive transmitter package (Model SI-2T) was obtained from Holohil Systems Ltd.

These packages were used

for the remainder of the study, primarily because battery life was improved to at least 600 days without loss of signal strength.

The greatest weight of any transmitter

19

implant package used was 10.5 g and represented less than 5% of the body weight of an implanted snake.

To reduce

potential behavioral changes due to transmitter implant mass, only snakes greater than 250 g were implanted. Radio signals were received with a 4 band, 12 channel portable telemetry receiver (AVM Instrument Company, Model LA12) using a 3- or 4-element hand-held yagi antenna.

Most

radio locations involved a visual observation of the individual tracked, except when it was underground, eliminating triangulation error.

At each initial location

or relocation, the time, distance and bearing to the previous location was recorded.

Movement distances are

minimum estimates because snakes were assumed to have moved in a straight line between successive locations.

Snakes

were relocated approximately once every 48 h.

Analytical Methods Between 10 August and 21 September 1993, the capture location, overwintering location, and other significant locations (birth sites, position following a move of a relatively long distance in a short time span) for each of the telemetered snakes monitored since 1989 were determined with a Global Positioning System (GPS).

Magellan Systems

Corporation NAV-5000 PRO receivers and Hewlett Packard 95LX Palmtop computers were used to collect and store position data at each location.

Point locations from all but two

have Position Dilution of Precision (PDOP) values of 6.0 or

20

less (two points had PDOPs of 6.3).

PDOP is a measure of

the possible error associated with the geometry of the satellites.

PDOP values below 6.0 provide for point

accuracies of 5 m or better.

Position fixes were recorded

as geographic coordinates (LAT-LONG) in the World Geodetic System 1984 Datum (WGS 84).

Data from the receivers were

post-processed against an Ashtech Ranger base station receiver, using Magellan version 2.8 software, to obtain accuracies of 2-5 m for each located point.

The base

station was operated over a better than second order (cm accuracy) control point located approximately 190 km east of CSWMA on the roof of the NYSDEC's Wildlife Resources Center, in Latham, New York.

The corrected points in WGS 84 were

then converted to Universal Transverse Mercator (UTM) coordinates in the North American 1927 Datum (NAD 27) using the U.S. Army Corps of Engineers program CORPSCON version 3.01.

GPS data were prepared by J. Ozard (Habitat Inventory

Unit, NYSDEC). The distance and bearing (polar coordinates) to each position subsequent to the capture or overwintering location were converted to UTM cartesian coordinates.

These UTM

coordinates were loaded into the program HOME RANGE (Ackerman et al. 1989) to determine estimates of each individual's annual movements and activity range.

Activity

range size was calculated using the minimum convex polygon method (Jennrich and Turner 1969) and the harmonic mean method (Dixon and Chapman 1980).

The convex polygon method

21

results are reported to facilitate comparisons with other studies that use this method (Macartney et al. 1988).

The

harmonic means are also reported because they produce an estimate that is influenced by the distributions of radio locations and can identify multiple core areas (Tiebout and Cary 1987, Reinert 1992).

However they may enclose areas

that were never visited by individual snakes.

Using these

methods, the 100 % convex polygon and the 95% harmonic mean isopleth

represent the total activity range and the 50%

convex polygon and the 50% harmonic mean isopleth represent the core area (Tiebout and Cary 1987, White and Garrott 1990).

The 50% convex polygons are determined by removing

the furthest point from the geometric mean of all locations, then recalculating the geometric mean and removing the furthest point from the remaining locations and repeating until 50% of the locations are removed (Ackerman et al. 1989). A time series analysis (Reinert and Zappalorti 1988, Reinert 1992) was performed to detect shifts in activity over time on individuals tracked at least 90 days.

Location

data for these individuals were grouped into 30 - 40 day intervals and the 100% convex polygon was calculated to determine time series activity ranges.

The summed areas

(minus overlap) per active season from the time series analysis were used to compare with the total season activity ranges.

22

One-way ANOVA (ÿ = 0.05) was used to test for differences in movement parameters and activity range between males, nongravid females and gravid females and between 100% convex polygon and summed time-series activity range.

Chi-square goodness-of-fit tests were used to

examine differences between years among individuals with multiple activity season tracking.

The Pearson product

moment correlation was used to test for correlation between snout-vent length (SVL) with total distance moved, mean distance moved per day and, for individuals tracked for at least 100 days, activity range size (100% and 50% convex polygons).

Gravid females were excluded from these

correlation analyses. To visualize activity ranges of individual snakes, I digitized a cover type map of Cicero Swamp from a 1992 high-altitude color infrared aerial photograph into the geographic information system GRASS (USA-CERL 1991).

The

digitized map file was converted to a format suitable for the CAD package EasyCAD2.

The coordinates of individual

snakes' 100% and 50% convex polygon output from HOME RANGE were entered into EasyCAD2 to plot the activity ranges and core areas on maps of CSWMA.

RESULTS Between 1989 and 1992, a total of 1097 observations for 14 monitored snakes was obtained.

Some individuals were

23

tracked for multiple years (2 years, n = 6; 3 years, n = 3), although only three snakes were tracked for two complete seasons.

Movement parameters of all monitored massasaugas

are given in Table 2.1 and activity ranges are shown in Table 2.2. Subsequent to spring emergence, the general movement pattern for male and nongravid female massasaugas was to leave the relatively open transitional peatland (Burn Area) and move into the surrounding swamp forest and uplands.

The

movement was typically preceded by a period of 10-20 days of relative inactivity near the overwintering location.

Gravid

females remained in the Burn Area until 10-12 days following parturition, at which time they moved beyond the borders of the Burn Area.

This pattern observed in telemetered

individuals supports field observations of non-telemetered gravid females.

Core areas of gravid females were entirely

within the Burn Area. Differences were detected between sex and reproductive condition for mean frequency of movements (F2,12 = 5.27, P = 0.02)(Table 2.3) where gravid females made fewer movements (45.5% of the observations).

No differences were detected

between male and nongravid female massasaugas.

Similarly,

differences were found in mean distance moved per day (F2,12 = 4.34, P = 0.04) and mean distance moved per season (F2,12 = 4.18, P = 0.04) where LSD posteriori tests indicated gravid females made smaller movements than either males and nongravid females.

No differences were detected between

24

male and nongravid female massasaugas for these parameters, although some individual male snakes made extensive, but episodic, long movements (four instances of > 1 km straight-line distance in two days). Range length differed among all three classes (F2,12 =convex polygon 9.77, P = 0.003).

Nongravid females showed

the greatest mean range length (1212.4 m), followed by males (812.6 m) and gravid females (295.6 m). Mean 100% convex polygon activity range size for all massasaugas monitored in CSWMA was 26.2 ha, while mean 95% harmonic mean isopleth was 44.3 (S.E. + 7.409) ha.

Convex

polygon estimates averaged 60% of harmonic mean estimates and were significantly positively correlated (r = 0.90, P < 0.01).

Similarly, mean 50% harmonic mean isopleth was

greater than 50% convex polygon (9.91 + 1.93 vs 5.2 + 1.15) and were positively correlated (r = 0.69, P < 0.01). There were significant differences among sex and reproductive condition groups (F2,12 = 3.88, P = 0.05) with gravid females utilizing smaller activity ranges than males or nongravid females (Table 2.3). did not differ significantly.

These latter two groups

Figure 2.2 illustrates

typical 100% minimum convex polygons for a male, nongravid female and gravid female eastern massasauga in CSWMA.

No

significant differences were detected in core areas among these groups (F2,12 = 1.98, P = 0.18).

The mapped activity

ranges and core areas of individual massasaugas tracked in CSWMA over the period 1989-1992 are shown in Appendix 1.

25

Time series analysis of all snakes tracked at least 90 days are reported in Table 2.2.

These values are the sum of

100% convex polygon activity ranges (minus overlap) for four successive time periods, each 30-40 days in length, and are more realistic estimates of actual activity range than estimates from the entire season's movements.

The total

area of these seasonal ranges for 15 individuals averaged 53.1 + 3.5% of the 100% convex polygon activity range. Gravid females seasonal ranges covered a greater percentage (F2,12 = 11.22, P < 0.01) of the total range ( = 78 + 4.98) than it did for males ( = 51.1 + 2.76) or nongravid females ( = 39.11 + 2.17).

Figure 2.3 illustrates time series

activity ranges for a typical male eastern massasauga. No significant correlations were detected between SVL and frequency of movement (r = 0.02, P = 0.944), mean distance moved per day (r = 0.14, P = 0.643), total distance moved (r = 0.04, P = 0.885), range length (r = 0.37,

P =

0.212), 100% activity area (r = 0.06, P = 0.850) or 50% activity area (r = -0.11, P = 0.728) among male and nongravid female snakes combined.

Male snakes tested alone

also showed no significant correlations for these measures. There was a significant positive correlation among male snakes between number of days tracked and total distance moved (r = 0.56, P = 0.024), although 100% activity ranges were not correlated with number of days tracked (r = 0.26, P = 0.395).

Female groups sample sizes were judged too small

for a similar analysis.

26

Three snakes were tracked for two complete successive seasons.

Male snake 2.27 and male snake 1.3 showed no

significant differences between years (ÿ2 = 1.98, P > 0.2 and ÿ2 = 0.39, P > 0.5 respectively), however male snake 3.2 used a significantly larger activity range (ÿ2 = 9.37, P < 0.01) in 1991 than 1990.

There was significant overlap of

activity range by individual snakes between years although core areas shifted annually (Fig. 2.4 and Fig 2.5.).

Discussion Gravid females, telemetered or not, were never encountered outside of the Burn Area over the course of the study.

All three telemetered snakes had small activity

ranges and restricted movements, generally in the vicinity of their previous winter's hibernation location.

The total

size of their activity ranges was increased by brief, but extensive, movements following parturition.

Gravid females

of several snake species have been shown to exhibit smaller movement parameters than males and nongravid females, including Crotalus horridus (Reinert and Zappalorti 1988), C. cerastes (Secor 1994), Agkistrodon contortrix (Fitch and Shirer 1971, Pseudechis porphyriacus (Shine 1987) Viper berus (Viitanen 1967), and Coluber constrictor (Brown and Parker 1976b). Activity and hibernation sites within the Burn Area tended to be concentrated at either the north or south ends. Qualitative examination of these areas within the Burn Area

27

indicates the vegetation is significantly shorter, hummocks are more well developed, and hollows are generally wider and more likely to contain standing water.

Chapter 3 discusses

habitat preference of massasaugas in this habitat. Following spring emergence, male and nongravid female massasaugas moved out of the transitional peatland habitat into surrounding swamp forest and uplands. were directed north, west or south.

All movements

Overwintering sites

were generally on the periphery of the activity range. Individual snakes monitored over multiple years showed different core areas each year (Appendix 1), although 100% convex polygons generally overlap.

Similar shifts in core

areas were also detected in the viperids Crotalus cerastes (Secor 1994) and Crotalus horridus (Reinert and Zappalorti 1988), the colubrids Natrix natrix (Madsen 1984) and Nerodia sipedon (Tiebout and Cary 1987) and the boid Morelia spilota (Slip and Shine 1988). There is little evidence of territorial behavior or intraspecific mutually-exclusive activity ranges in snakes (Gregory et al. 1987, Macartney et al. 1988).

Instead, many

snake species show overlapping activity ranges (Viitanen 1967, Wharton 1969, Brown and Parker 1976b, Madsen 1984, Macartney et al. 1988).

Limitations in such resources as

food, summer refugia, oviposition sites, and overwintering sites have been proposed to explain this apparent lack of territoriality (Gregory 1982, Duvall et al. 1985, Weatherhead and Hoysak 1989, Secor 1994).

Reinert and

28

Kodrich (1982) suggested the specific habitat requirements of gravid massasaugas accounted for a detected overlap in activity range.

In CSWMA, overlapping core areas are

probably related to the concentration of hibernation and gestation sites within the Burn Area and the generally widely-spaced foraging opportunities found in the surrounding swamp forest. Male snakes continue to move throughout the active season, however no expansion of activity range occurred with increasing days tracked beyond 100 days.

This supports

field observations that suggest male massasaugas are making a return movement toward the Burn Area at some critical point in the active season.

One possible explanation is

that males are moving closer to the Burn Area to increase their chances of encountering female massasaugas.

Field

observations indicate that courtship and mating occur in August-September at CSWMA and most of these observations were near the periphery, but not within, the Burn Area. Time series analyses that combine seasonal ranges preferable to total activity range because areas not used by the individual are excluded.

This may be especially

valuable where portions of the total activity range are obviously unsuitable, a condition that was not the case in CSWMA.

This approach has been used in studies of Natrix

natrix (Madsen 1984), Crotalus horridus (Reinert and Zappalorti (1988), Crotalus cerastes (Secor 1994), and Morelia spilota (Slip and Shine 1988).

29

Two telemetric studies have previously been published on eastern massasauga movement and activity pattern. Reinert and Kodrich (1982) studied massasaugas in two disjunct sites in western Pennsylvania.

One site was a

small (8 ha) open meadow intensively managed to retard encroachment of surrounding deciduous forest and maintain relict prairie.

The other site was a 36 ha old field where

agriculture has been abandoned since the mid 1940's.

These

sites more closely resemble massasauga habitats in wet prairie ecosystems (Maple and Orr 1968, Bielema 1973, Seigel 1986) in the midwestern United States.

Nearly all the

activity at these sites occurred in open vegetational communities with little movement into surrounding forest. Movements and activity ranges were considerably smaller at these Pennsylvania sites than at CSWMA (Table 2.4).

These

authors also noted no differences between gravid females and other snake groups in several movement parameters (except range length). There are several explanations for these differences observed between CSWMA and the Pennsylvania locations. First, Reinert and Kodrich's snakes were force-fed transmitters and this may reduce movements by inducing thermophily or simulating meals (Reinert and Cundall 1982, Lutterschmidt and Reinert 1990).

Second, individuals in

this study were tracked for relatively short periods, never for a complete active season.

Gravid snakes may, in fact,

move less over smaller ranges than other members of the

30

population at the two Pennsylvania sites.

Finally, and most

convincing, is that all life requisites may be met within the meadow and old field habitats of western Pennsylvania. Massasaugas hibernate in crayfish (Cambarus sp.) burrows that occur in these open habitats where basking opportunities abound.

Small mammals, the primary prey of

massasaugas (Keenlyne and Beer 1973, Seigel 1986) are low in abundance in the Burn Area.

Peatlands typically support a

lower abundance and diversity of small mammals than upland habitats (Nordquist 1992).

Some recent observations (D.

Johnson, pers. commun.) indicate that massasaugas may utilize forested habitat at the meadow site to some extent. The other previous study was on the Bruce Peninsula in Ontario, largely within the Bruce Peninsula National Park (BPNP), which contains a relatively large, disjunct population of eastern massasaugas near the northern extent of their range (Weatherhead and Prior 1992).

Activity

ranges of massasaugas there were nearly identical to those in this study (Table 2.4).

Massasaugas in BPNP moved more

than twice as far per day, but moved significantly smaller total distances.

This may be partly explained by the

shorter tracking periods ( = 36.5 days) in the Canadian study.

Females reportedly had significantly smaller

activity ranges and other movement parameters than males, however it was unknown or unclear if any of the females were gravid.

Gravid snakes would most likely influence

conclusions about sex differences and movement.

Mean range

31

length was substantially longer in the Canadian population suggesting the shape of the activity polygons at BPNP may have been more elongate than those at CSWMA.

Snakes at BPNP

showed a clear association with coniferous forest openings and wetlands in summer, fall, and at hibernation and an avoidance of open areas and other forest types.

Wetlands

composed only a small percentage of available habitat at BPNP. Due, in part, to size constraints imposed by the transmitter package and to a relatively small population of secretive snakes, movement parameters obtained for this population of massasaugas were restricted to larger adult animals.

Very little is known about neonate and subadult

massasaugas at CSWMA, population classes that may suffer the greatest risk of mortality (Scott and Seigel 1993). Neonates and small massasaugas were never encountered outside of the Burn Area, however, they may very well travel into adjacent habitats.

Recent evidence from radiomarked

neonate massasaugas in Wisconsin suggests they may move considerable distances over the period between birth and hibernation (R. King pers. commun.)

Management Implications The results of this study indicate that the transitional peatland habitat is critical for the survival of the eastern massasauga in CSWMA, and its primary value

32 lies in containing the majority of suitable overwintering sites for all members of the population as well as primary gestation sites for gravid females.

Prior to this study, it

was believed that most massasaugas in CSWMA remained in the Burn Area throughout the active season (Reixinger and Peterson 1982) and presumably met all their life requisites there.

Based upon observed movement patterns in this study,

males, nongravid females, and postpartum females left this habitat, possibly for more profitable foraging habitat (Chapter 4) in surrounding forested swamp and limited area of uplands within a reasonable distance from the peatland. This pattern of movement suggests that management activities need to focus on the juxtaposition of several habitat types, especially where critical wetland types, such as the transitional peatland in CSWMA, support low small mammal populations.

33 CHAPTER 3. HABITAT UTILIZATION BY THE EASTERN MASSASAUGA (Sistrurus c. catenatus) IN A NEW YORK WEAKLY-MINEROTROPHIC PEATLAND

INTRODUCTION Human activity that results in loss or fragmentation of habitat is generally regarded as the prime contributor to the reduction of biodiversity (Wilcove et al. 1986, Wilson 1988, 1992, Meffe and Carroll 1994).

Additionally, an

ecosystem containing a species' specific habitat may appear relatively unperturbed at the level of the landscape, but subtle changes, natural or otherwise, at smaller scales may be occurring that could ultimately lead to local extinction. Therefore, knowledge of an endangered, threatened, or rare organism's specific habitat requirements is critical to decisions regarding the establishment of management plans or recovery strategies.

Yet, much of our knowledge about a

species' habitat preferences is of a qualitative nature (Thomas 1982) which has limited predictive or comparative value and provides only a coarse-grained assessment of an organism's needs. It is especially critical that unbiased estimators be used to assess the habitat preferences of species for which some management action designed to increase the quantity or quality of habitat is planned.

Such estimators should

identify, in an easily-quantifiable way, which habitat variables are most important in defining a species' preferences and will provide the most useful information for

34

developing habitat management guidelines.

Additionally,

these estimators should be developed and measured on a spatial scale that is most appropriate for the needs of the species in question. The purpose of this chapter is to quantify the structural habitat and examine intraspecific habitat variation by sex and reproductive condition of the eastern massasauga, Sistrurus c. catenatus, in a transitional peatland habitat.

This relatively small rattlesnake shows a

clear association with wetland habitats across its range (e.g., Wright 1941, Reinert and Kodrich 1982, Seigel 1986, Weatherhead and Prior 1992).

Wetlands are particularly

important to eastern massasaugas for overwintering (Maple and Orr 1968, Johnson - Chapter 2).

It has been estimated

that over 50% of the 80 million ha of wetlands that originally existed in the lower 48 states have been destroyed, fragmented, or otherwise altered (Feierabend and Zelazney 1987).

Consequently, the eastern massasauga is

listed variously as endangered, threatened, or of special concern in all of the states and the one Canadian province that constitute its range (Figure 1.1).

METHODS Study Area This study was conducted in Cicero Swamp consisting of the Cicero Swamp Wildlife Management Area (CSWMA) and adjacent private land in Onondaga County, New York, 15 km

35

northeast of the city of Syracuse (Fig. 2.1).

CSWMA is

approximately 2040 ha in size and most of it is owned and managed by the New York State Department of Environmental Conservation.

Average annual temperature is 8.7oC, average

January temperature is -4.7oC, average July temperature is 21.5oC and mean annual precipitation is 95.5 cm evenly distributed throughout the year (Hutton and Rice 1977).

The

proximity of the site to Lake Ontario and Oneida Lake exerts a moderating influence on regional climate, although snowfall is heavy, averaging between 254 and 305 cm annually (Hutton and Rice 1977). CSWMA is primarily a weakly-minerotrophic peatland complex consisting of mostly forested wetlands composed largely of red maple (Acer rubrum). Chase (1964) identifies four subcategories within this cover type based upon the relative abundance of tree species codominant or subdominant to red maple.

The most abundant, wettest type consists of

mostly A. rubrum (85% of tree basal area) with a smaller component of yellow birch (Betula alleghaniensis), American elm (Ulmus americana) and white ash (Fraxinus americana).

A

second community type is generally drier with A. rubrum and white pine (Pinus strobus) comprising 90% of the tree basal area.

A third type was considered by Chase to be the most

mesophytic and A. rubrum, eastern hemlock (Tsuga canadensis) and scattered black gum (Nyssa sylvatica) were the dominant trees.

36

Within CSWMA, and near its western periphery, is a 37 ha transitional peatland, defined as intermediate between minerotrophic and ombrotrophic peatlands (Mitsch and Gosselink 1993), which resembles a shrub-carr. This peatland is especially important to the CSWMA massasauga population, primarily for overwintering and gestation.

This is the

final cover type identified by Chase (1964).

The

vegetation structure in this area is clearly distinct from surrounding swamp habitat types, both on the ground and from examination of aerial photographs.

Its appearance is

primarily due to an intense fire that consumed up to one meter of peat while the area burned from June 1892 until the following January (LeBlanc and Leopold 1992).

This area

will be hereafter referred to as the "Burn Area".

The

microtopography generally consists of hummocks supporting trees and shrubs interspersed with hollows.

The ground

vegetation layer is composed of approximately 50% bryophytes, mostly Sphagnum spp. and Polytrichum spp. (LeBlanc and Leopold 1992).

The dominant shrub species are

mountain-holly, (Nemopanthus mucronata), highbush blueberry, (Vaccinium corymbosum), and black chokeberry, (Aronia melanocarpa), although leatherleaf, (Chamaedaphne calyculata), is abundant in areas of lower shrub growth. Tree species include black spruce (Picea mariana), Acer rubrum, tamarack (Larix laricina), and European white birch (Betula pendula).

A more complete description of the Burn

37

Area is found in LeBlanc (1988).

Nomenclature follows

Mitchell (1986) for all vascular species.

Telemetric and Sampling Methods Massasaugas were located by systematic searches in appropriate habitat at CSWMA.

Each captured individual was

weighed, measured, and given an individual mark by clipping the right or left half of one or two ventral scales (Brown and Parker 1976a).

A subset of massasaugas captured at

CSWMA was taken from the field for implantation of radiotransmitters.

All implants were interperitoneal using

a modification of the methodology of Reinert and Cundall (1982), with the antenna inserted subcutaneously.

The major

modifications were the use of the inhalent anesthetic methoxyflurane in place of halothane (Aird 1986) and the mode of delivery of the anesthetic.

Anesthesia was

administered via a plastic cone placed over one end of a clear plexiglass tube containing the snake and rates of delivery and relative proportion of the anesthetic and oxygen could be monitored and adjusted.

In 1989, AVM model

SM-1 transmitters fitted with Mallory HG625 or HG675 mercury batteries and 30-40 cm whip antennas were used.

Batteries

and antenna were affixed to the transmitter upon receipt and the package was potted with a 50:50 mixture of beeswax and parrafin (Reinert 1992).

These transmitters had a battery

life of approximately 160 days and maximum transmission distances of 800 m.

Beginning in 1990, an implantable

38

temperature-sensitive transmitter package was obtained from Holohil Systems Ltd. (Model SI-2T).

These packages were

used for the remainder of the study, primarily because battery life was improved to at least 600 days.

The

greatest weight of any transmitter implant package used was 10.5 g and represented less than 5% of the body weight of an implanted snake.

To reduce potential behavioral changes due

to transmitter implant mass, only snakes greater than 250 g were implanted. Radio signals were received with a 4 band, 12 channel portable telemetry receiver (AVM Instrument Company, Model LA12) using a 3- or 4-element hand-held yagi antenna.

At

each initial location or relocation, the time and distance and bearing to the previous location were recorded.

Snakes

were relocated approximately once every 48 h, resulting in a total of 1097 observations for the 14 monitored snakes [n = 71 observations in 1989 on four individuals (three male, one female-nongravid); n = 439 observations in 1990 on six individuals (four male, two gravid female); n = 391 observations in 1991 on eight individuals (six male, two female-nongravid), n = 196 observations in 1992 on five individuals (three male, female).

onefemale-nongravid, one gravid

Some individuals were tracked for multiple years

(two years, n = six; three years, n = three). Snake body temperature was determined from the pulse rate of the transmitters.

Pulse rate can be determined by

counting either the number of pulses over some interval (1

39

min) or by determining the time interval between pulses (msec).

The latter is more accurate (Reinert 1992) however

it requires a timer linked to the receiver which was not available for this study, therefore the former was used. Each transmitter was calibrated against four temperatures (00, 150 300 and 450 C) in water baths.

A regression

equation using logarithmically transformed pulse rate data was calculated for each transmitter to convert pulse rate into snake body temperature. Based upon movement patterns first observed in 1989, where male and nongravid female snakes generally left the Burn Area and gravid females remained exclusively within the Burn Area until parturition, the available habitat was divided into a) Burn Area habitat and b) "Swamp" habitat (essentially variously-aged red-maple swamp forest, but does include a minor, yet significant, component of old field and agricultural land).

The following analyses were performed

separately for each habitat type. Beginning in 1990, at each animal's initial location and subsequent relocations 14 topographic and structural variables were measured (Table 3-1).

Only locations where a

snake was observed coiled or looped were used for analysis; snakes in an outstretched posture were likely interrupted in motion.

Similarly, since many movements between successive

observations were very small, only locations separated by at least two days and greater than three m from a previous location were used.

Animal locations within 10 m of either

40

side of abrupt habitat edges or within broader ecotonal areas between Swamp and Burn Area habitats were not used for analysis.

Since only three telemetered gravid females were

available for analysis, habitat observations from three non-telemetered individuals were also used.

These

individuals were located repeatedly from their initial capture location until parturition. To determine if snake locations were selected randomly with respect to available habitat in the two habitat types, 110 and 75 random sites were sampled in an identical manner to snake locations in the Burn Area habitat and the Swamp habitat, respectively.

These random points were selected by

placing a grid over the area bounded by the outermost radiolocations of all snakes within the two habitat types and choosing coordinates from a table of random numbers.

Statistical Analysis In the Burn Area habitat, observations were separated into four sampling groups: male, nongravid female, gravid female, and random.

Since gravid females were never

encountered outside the Burn Area (P. Riexinger, pers. commun.; Chapter 2), the Swamp habitat consisted only of male, nongravid female, and random sampling groups.

In both

habitats there were significantly more male observations than either female category therefore a randomly selected subset of the male data was used to keep sample sizes similar.

Two sets of data, consisting of raw and a mixture

41

of arcsine (for percent data) and log transformed data were used in the analysis.

Since both sets produced results with

nearly identical biological interpretations and transformed data still did not meet the assumptions of multivariate normality and equal variances, the raw data values are reported here. Multivariate analysis of variance (MANOVA) in the General Linear Model (GLM) procedures (SAS Institute Inc. 1985) were used to determine if group centroids differed significantly.

Canonical discriminant analysis was used to

examine the relative contribution of the variables to group separation (Tardif and Hardy 1995).

Direct discriminant

analysis was used to classify each group based upon a function derived from a linear combination of the variables that maximized separation among groups (Williams 1983).

The

discriminant model was tested using a jacknife resampling procedure (Verbyla and Litvaitis 1989).

One-way ANOVA

output from the MANOVA was used to assess significance (P < 0.05) of each variable for each habitat type.

To better

explain among-group differences mean separation tests (Tukey's HSD) were conducted on each variable (Petersen 1985).

SAS (SAS Institute Inc. 1990) was used for all

statistical analyses. As a test of the stability of variables used in the discriminant model, a stepwise logistic regression procedure was used to select the "best" set of predictor variables that would correctly classify snake and random locations

42

(Capen et al. 1986).

Unlike discriminant analysis, only two

classes can be tested simultaneously so several combinations of random locations and the three snake classes were tested, including combining all snake classes.

Only variables with

coefficients significantly different from zero at P

< 0.05

were retained in the model (forward stepwise regression). The signs of the logistic regression coefficients indicated the direction of the nonlinear association between the predictive variable and the probability of a location belonging to either of the two classes.

The logistic

regression models yield the natural log of the ratio of the probability that an event (e.g., being classified as a random location) will occur to the probability that it will not (being classified as a snake location).

The critical

probability (logistic cutpoint) above which a location was classified as a snake location (or male snake location in some models) was 0.5.

RESULTS Burn Area Habitat A total of 75 location sites from six (three telemetered) gravid female Sistrurus c. catenatus, 58 location sites from four non-gravid female S. c. catenatus, 63 location sites from 10 male S. c. catenatus, and 75 random sites were used in the analysis.

A MANOVA for the

four groups with 12 variables showed that there were

43

significant differences between the groups' centroids (Wilk's lambda = 0.250, F (33,758) = 13.82, P < 0.01). Gravid females showed the greatest differences among groups for the habitat variables measured (Table 3-2).

They

occurred in areas within the Burn Area habitat with a lower woody stem density ( = 16.6/m2), with a much reduced canopy cover ( = 3.53%) and maximum shrub height ( = 0.31 m) than random sites or other snakes locations.

Gravid females were

also typically located further from vegetation greater than 1 m in height than other groups.

Less moss (31.7%) and more

vascular vegetation (50.7%) covered the ground layer in locations where gravid females were encountered compared to a random site or where nongravid snakes occurred. Nongravid females differed from all other groups in only one measured habitat feature, the distance from the edge of a hummock. These snakes appeared to be found closer to the interior of a hummock ( = 0.49 m).

They were found

closer to woody vegetation greater than 1 m in height than other snakes and were similar to random points in this regard.

For most habitat features, males and nongravid

females were similar to each other and differed significantly from random sites. All snake groups were more likely encountered in areas with lower shrub stem density, shrub height, and shrub canopy coverage (Table 3-2) and were typically further from hollows than random points.

The ground cover at snake

44

locations generally had less moss coverage and more non-bryophyte vegetation than random sites. Variables loaded highest (>+0.50) on the first canonical axis were maximum shrub height (0.776), relative coverages of moss (0.737) and other vegetation (-0.693), distance to vegetation greater than 1 m in height (-0.590), and shrub canopy cover (0.553) (Table 3-3).

Negative and

positive signs indicate opposite patterns of response.

This

axis represents a structural habitat gradient within the Burn Area of taller shrubby vegetation with a denser shrub canopy and a ground cover dominated by mosses to lower shrubs with a sparser canopy and a reduced bryophyte ground cover.

Axis two was most influenced by the distance of the

sample point to the hummock's edge from its interior or, if the point was located in a hollow, the distance to the nearest hummock. The first two canonical axes explained 85.4% of the variation among groups, although a two function plot did not reveal four distinctly separated groups (Fig 3.1). Mahalanobis pairwise squared distance between groups, an indicator of distance between groups in discriminant space, showed that gravid females and random sites were most separated (7.6) while male and nongravid female group centroids were closest (2.9). The direct discriminant function correctly classified 100% of the gravid females and 89.3% of the random sites (Table 3-4). Overall classification accuracy was 71.1%.

The

45

discriminant function was least successful in classifying male snakes, where 46% were misclassified as gravid females. Only 25.4% were correctly classified.

The crossvalidation

technique reduced the overall classification accuracy to 63.8% (Table 3.5). The logistic model of all snake locations against random locations in the Burn Area habitat (Model 3, Table 3.6) correctly classified 92.9% of the snake locations and 65.3% of the random locations, for an overall predictive capability of 85.2%.

In this model, the probability of a

location being used by a massasauga was highest where maximum shrub height and percent moss cover was low and if the location was on the edge of a hummock near a hollow. The logistic model for males versus nongravid females in the Burn Area habitat indicated the probability of male snake use increased as the distance to taller vegetation and the relative ground cover of leaf litter decreased and as the distance to a hollow increased (Model 4, Table 3.6), suggesting male and nongravid females were separating by position in hummock vegetation.

Males preferred the center

of hummocks with more leaf litter while females were found more often along the periphery of a hummock. Calculating the probability of use by both of these groups compared to random sites within Burn Area habitat (Model 5, Table 3.6) required two variable measures to predict with an overall 84.7% accuracy.

Snakes were more

likely to be found in areas with less moss cover and at

46

greater distances from the hollows between hummocks.

The

addition of three more variables (MAXSHBHT, GLIT, and GSOIL) improved the overall prediction accuracy to 87.2%.

"Swamp" Habitat A total of 110 location sites from 12 male S. c. catenatus, 62 location sites from four non-gravid female S. c. catenatus, and 103 random sites were used in the analysis.

A MANOVA for three groups with 15 variables

showed that the groups' centroids were significantly different (Wilk's lambda = 0.378, F (28,518) = 11.60, P < 0.01). S. c. catenatus of both sexes were typically found closer to overstory trees and logs greater than 7.5 cm in diameter in areas of lower canopy coverage than random sites in the Swamp habitat (Table 3.7).

Ground cover near snakes

had less moss cover, but more non-bryophyte vegetation and logs than random sites. Male snakes were encountered in areas of lower woody stem density ( = 19.9/m2) and were closer to canopy gaps greater than 10 m wide ( = 4.1 m) than either females or random points were.

Male snakes were found closer to logs

than were random points, however nongravid female snakes were not closer to logs than were random points.

Male

snakes were found near larger logs ( = 16.8 cm diameter) than female snakes ( = 12.5).

47

Variables loaded highest (>+0.50) on the first canonical axis were percent canopy closure (0.622), and the relative coverages of non-bryophyte ground vegetation (-0.660) and of mosses (0.612) (Table 3-8).

This axis

represents a structural habitat gradient within the Swamp habitat from areas of greater canopy closure with more moss ground cover to reduced canopy closure with more herbaceous and low woody vegetation on the ground.

Axis two was most

influenced by the diameters of overstory trees and fallen logs, however neither of these measures were loaded higher than 0.50. The first canonical axis explained 77.7% of the variation among groups.

A two function plot revealed that

snake groups were most nearly separated from random locations along the first axis and males were not completely separated from females along the second axis (Fig 3.2). Mahalanobis pairwise squared distances between groups showed that males were most separated from random sites (5.3), the female centroid was separated from the random centroid by 4.3 and male and female group centroids were closest (2.3). The direct discriminant model correctly classified 98.4% of the nongravid females and 90.3% of the random sites (Table 3-4). The model was less successful in classifying males (81.8%).

Of the 20 misclassifications, more than

twice as many (12.7% of total) were classified female than random (5.5% of total).

Overall classification accuracy was

48

90.1%.

The crossvalidation technique reduced the overall

classification accuracy to 87.4% (Table 3.5). The logistic model of all snake locations against random locations in this habitat (Model 1, Table 3.6) correctly classified 97.7% of the snake locations and 76.6% of the random locations, for an overall predictive capability of 90.9%.

In this model, the probability of a

location being used by a massasauga was highest where canopy closure and relative percent moss cover were low and where distance to understory vegetation was greater and percent non-bryophyte ground cover was relatively high. The logistic model for male versus nongravid female massasaugas in the Swamp habitat (Model 2,Table 3.6) required three variables to predict classification probability with an over all accuracy of 80.8%.

In this

habitat type, males were more likely found in areas with less dense woody vegetation and larger trees and closer to canopy gaps greater than 10 m wide than female snakes.

Temperature Over the period that female snakes were gravid, mean body temperature was significantly higher (F2,12 = 61.31, P < 0.01) for gravid females than nongravid females and males (Table 3.9).

Similarly, the body/air temperature ratio was

significantly greater (F2,12 = 296.63, P < 0.01) for gravid females than the other two classes.

No differences were

detected between nongravid females and males.

Following

49

parturition until entrance to overwintering sites, no differences were observed between any of the groups for mean body temperature (F2,12 = 0.25, P > 0.79) or body/air temperature ratio (F2,12 = 0.84, P > 0.46)(Table 3.9.).

Discussion Habitat Models The two most important variables (i.e. with highest loadings on the first canonical axis) in the discriminant model for massasaugas in the Burn Area habitat (maximum shrub height and % moss ground cover) also appear in the logistic regression model (Model 3) as most useful in predicting a location in terms of snake use.

Similarly,

distance of a location to a hummock is loaded highest on the second canonical axis and this measure also appears in the logistic regression model.

In the Swamp habitat, three of

the four variables (canopy closure, and relative percentages of moss and non-bryophyte vegetation in the ground cover) entered and used in the logistic regression model between random and snake locations (Model 1), were also loaded highest on the first canonical axis of the discriminant model. While logistic models are two class models (random vs. snake), this apparent stability of variables (Capen et al. 1986) suggests they are very useful measures of massasauga use in both peatlands and other wetland ecosystems.

50

The discriminant model was very successful in separating snake locations from random locations in the Burn Area habitat.

Only 5.6 of the snake locations were

misclassified as a random site (8.1% from jacknife procedure) indicating snakes are clearly selecting from the available habitat.

The discriminant classification results

also suggests that significant portions of the "Burn" Area are largely unsuitable for massasaugas.

Percent moss cover

was negatively correlated with snake use, and LeBlanc and Leopold (1992) found total percentage cover of bryophytes to be 48% in the Burn Area while herbaceous plants only accounted for 18.2% of the ground cover.

They also found a

negative relationship between tree seedling, shrub understory density and herbaceous cover with basal area of canopy shrubs, suggesting that as shrubs form a dense canopy, there is a concommittant decrease in high-quality massasauga habitat. The discriminant model was even more successful in classifying snake from random locations in the Swamp habitat.

Here, only 3.5% of the snake locations were

misclassified as random locations (5.2% from the crossvalidation procedure). No other published studies have quantified an unbiased estimator of massasauga habitat.

Most studies provide

generalized qualitative descriptions of "optimal" massasauga habitat (Swanson 1930, Wright 1941, Maple and Orr 1968). Reinert and Kodrich (1982) presented a description of

51

habitat that was the first to use data gathered from telemetered individuals.

They, like some previous authors

(Wright 1941, Swanson 1952), found little or marginal use of forested habitats.

Most massasaugas in their study remained

in open habitats with sparse vegetation and dry soils during the active season.

Reinert and Kodrich (1982) report a

distinct shift from low, wet habitats to these drier uplands.

Seigel (1986) likewise observed a habitat shift

from wet to dry, open habitat as the season progressed following spring emergence.

Weatherhead and Prior (1992),

whose study was also based upon the movements of telemetered massasaugas, found that there was a strong association with wetland and coniferous forest habitats and massasaugas avoided open habitats (such as roads and trails where most of their initial captures occurred) and mixed forest.

They

suggest the heavy use of coniferous forest may be an artifact of the landscape-level scale of measurement (satellite imagery) and snakes may have use forest openings consistently. A probable explanation for the reduced mobility of gravid females and their clear association with more open habitats within the Burn Area habitat is they are maximizing their ability to thermoregulate.

Gravid female body

temperatures were consistently higher than other snake classes until after parturition.

Charland and Gregory

(1990) have observed a similar pattern with Crotalus viridis in the northern portion of its range.

These data support

52

the hypothesis that viviparous gravid female snakes can exert some control over embryo development by thermoregulatory means. Nongravid females and male massasaugas appear to be thermoconformers during their active season.

Other needs,

such as finding food, are more important than maintaining the highest possible body temperatures.

In the Burn Area

habitat, nongravid females were found closer to the interior of hummocks than males.

In neither habitat type did they

appear to be selecting more open habitats than males. Consistent with this observation is that neither group differed significantly in their body-to-air temperature ratio.

Reinert (1984) suggested nongravid female Crotalus

horridus have a predisposition toward more open and presumably warmer habitats.

Females in his

biennially-reproducing population could generally not be considered nonreproductive in years they did not give birth because follicular development occurs in nongravid years (Gibbons 1972, Keenlyne 1978).

In massasaugas at CSWMA,

differences in habitat preference between nongravid females and males may not be the result of reproductive need, but rather reflect intraspecific competition for other resources such as food. The utilization of downed logs by some small mammal species (Dueser and Shugart 1978, Geier and Best 1980) may explain the association of massasaugas with this structural element in the swamp forest habitat.

Males tended to be

53

closer to larger logs than females.

Douglas and Reinert

(1982) showed that the diameter and length of fallen logs were not significant with respect to small mammal use, suggesting male snakes may use this feature for other functions, perhaps as a cover or retreat object, or it may be a proximate mechanism to reduce intraspecific competition between the sexes. Due to weight constraints relative to telemetry procedures in this study, no ontogenic analysis was performed on habitat preferences for massasaugas.

It is not

known if neonate or subadult massasaugas remain in the Burn Area habitat or move into surrounding Swamp habitat. Neonates were never found outside of the Burn Area and they are born late in the summer or early fall.

I suspect they

move little until overwintering and they locate their first meal in the peatland, if they even feed at all prior to hibernation.

Knowledge of movements by this first age class

is important to gather, given the suspected high mortality of neonates (Keenlyne 1968).

Management Implications I agree with Reinert (1993) that investigations such as this one should not be labeled "habitat selection", but rather "habitat utilization or correlation", because they do not test for the ultimate or proximate causes of the observed patterns.

However, these studies are necessary to

enable researchers to ask the right questions about habitat

54

selection and then design appropriate field and laboratory experiments.

Habitat correlation studies are especially

important for species that utilize several habitat types, both within populations and across their range.

The most

immediate value of habitat correlation studies will be to managers of natural resources.

It is especially important

that any programs that have a habitat management component consider studies designed to provide unbiased descriptions of preferred habitat and that intrapopulation and seasonal differences be considered. The habitat models developed in this study are most useful for peatland habitats, a community type utilized by massasaugas at several places in their range, although most large peatlands supporting massasaugas are near the range periphery (e.g., CSWMA and Bergen Swamp in New York, Wainfleet Bog in southern Ontario) and represent marginal refugia from the reduction of postglacial prairie habitat due to forest encroachment (Schmidt 1938). Managers whose responsibilities include massasaugas in other habitat types need to develop their own discriminant models or logistic regression equations using measures appropriate to that location.

Logistic regression models

are considered superior to discriminant models when data sets contain a mix of discrete and continuous variables (Press and Wilson 1978) and logistic cutpoints can be raised or lowered depending on the objectives of the management plan (Swallow et al. 1986).

55 Gravid massasaugas were typically found at either the northern or southern ends of the Burn Area habitat, where shrubby vegetation was shortest.

The clear separation of

gravid snakes from random sites indicates that availability of suitable habitat is most limiting for gravid females. Therefore, management prescriptions designed to benefit massasaugas in CSWMA should focus on the needs of gravid females.

56 CHAPTER 4. HABITAT MANAGEMENT FOR THE EASTERN MASSASAUGA IN A CENTRAL NEW YORK WEAKLY-MINEROTROPHIC PEATLAND: THE EFFECTS OF CUTTING, BURNING AND HERBICIDES ON VEGETATION AND SMALL MAMMAL ABUNDANCE.

INTRODUCTION The habitat loss accompanying the succession from low, open plant communities to relatively stable, closed-canopy forest has been recognized as a problem in the management of vertebrate species adapted to early successional plant communities (Anderson 1979, Thomas et al. 1982, Huff et al. 1985, Niederleitner 1993), including peatlands (Collins 1990, Richardson and Gibbons 1993).

Although few

vertebrates are obligate peatland species (Glaser 1987, Damman and French 1987), many meet at least part of their life requisites in peatlands (Sharitz and Gibbons 1982, Ewert 1982, Stockwell and Hunter 1989, Collins 1990, Berg 1992, Nordquist 1992, Niemi and Hanowski 1992, Karns 1992). The eastern massasauga (Sistrurus c. catenatus), a wetland associate across its range (Wright 1941, Reinert and Kodrich 1982, Seigel 1986, Weatherhead and Prior 1992), will utilize fen and transitional peatlands, especially in the eastern portion of its range (Wright 1941, Lovich and Jawarski 1988, Johnson and Breisch 1993, Middleton 1993). It appears wetlands are necessary for overwintering (Maple and Orr 1968, Hallock 1991), and in peatlands, the spaces within the root system beneath shrub hummocks and tussock

57

vegetation may be the primary overwintering locations (Chapter 6). The overall purpose of this study was to evaluate several methodologies designed to create open habitat which should favor eastern massasauga rattlesnakes in Cicero Swamp, a large transitional peatland in central New York (Chapter 3).

Specifically, cutting, burning and herbicide

application were evaluated in terms of their effectiveness in reducing woody stem densities and basal area over a three year period.

Additionally, eastern massasauga occurrence

and the abundance of small mammal prey populations in treated areas were estimated and related to data on habitat use by the eastern massasauga (Johnson and Reinert, in prep.). MATERIALS AND METHODS Study Site This study was conducted in the Cicero Swamp Wildlife Management Area (CSWMA) in Onondaga County, New York, 15 km northeast of the city of Syracuse (Fig. 2.1).

CSWMA is

approximately 2024 ha in size and is owned and managed by the New York State Department of Environmental Conservation (NYSDEC).

Average annual temperature is 8.7oC, average

January temperature is -4.7oC, average July temperature is 21.5oC and mean annual precipitation is 95.5 cm evenly distributed throughout the year (Hutton and Rice 1977).

The

58

proximity of the site to Lake Ontario and Oneida Lake exerts a moderating influence on regional climate.

CSWMA is primarily a weakly-minerotrophic peatland complex consisting of mostly forested wetlands composed largely of red maple (Acer rubrum). Chase (1964) identifies four subcategories within this cover type based upon the relative abundance of tree species codominant or subdominant to red maple.

The most abundant, wettest type consists of

mostly A. rubrum (85% of tree basal area) with a smaller component of yellow birch (Betula alleghaniensis), American elm (Ulmus americana) and white ash (Fraxinus americana).

A

second community type is generally drier with A. rubrum and white pine (Pinus strobus) comprising 90% of the tree basal area.

A third type was considered by Chase to be the most

mesophytic and A. rubrum, eastern hemlock (Tsuga canadensis) and scattered black gum (Nyssa sylvatica) were the dominant trees. The fourth cover type is represented by a 37 ha transitional peatland, defined as intermediate between minerotrophic and ombrotrophic peatlands (Mitsch and Gosselink 1993), that resembles a shrub-carr and appears especially important to the CSWMA massasauga population, primarily for overwintering and gestation.

The vegetation

structure in this area is clearly distinct from surrounding swamp habitat types, both on the ground and from examination of aerial photographs.

The appearance of this area is

59

primarily due to an intense fire that consumed up to one meter of peat while the area burned from June 1892 until the following January (LeBlanc and Leopold 1992).

This area

will be hereafter referred to as the "Burn Area".

The

microtopography generally consists of hummocks supporting trees and shrubs interspersed with hollows.

The ground

vegetation layer is composed of approximately 50% bryophytes, mostly Sphagnum spp. and Polytrichum spp. (LeBlanc and Leopold 1992).

The dominant shrub species are

mountain-holly, (Nemopanthus mucronata), highbush blueberry, (Vaccinium corymbosum), and black chokeberry, (Aronia melanocarpa), although leatherleaf, (Chamaedaphne calyculata), is abundant in areas of lower shrub growth. Tree species include black spruce (Picea mariana), Acer rubrum, tamarack (Larix laricina), and European white birch (Betula pendula).

A more complete description of the Burn

Area is found in LeBlanc (1988).

Nomenclature follows

Mitchell (1986) for all vascular species.

Experimental Treatments Fire and Cutting Treatments Sixteen 25 x 25 m (625 m2) plots (Fig. 4.1) were established in a relatively homogeneous portion of the Burn Area in the winter of 1990-1991.

No plot was less than 50 m

from the ecotonal area between the Burn Area and the surrounding forested swamp.

To characterize the woody

plant community, the number, height and diameter at ground

60

level (DGL) of all trees (woody stems > 5.0 cm dbh) were determined for each plot.

Five 1.0 m2 subplots also were

randomly established in each plot and all shrub stems > 10 cm were tallied by species and DGL classes of 2.5 cm to estimate density and basal area.

The mean height of

shrub stems was determined from the height of five representative stems in each subplot. Following measurement, all woody stems in each 625 m2 plot were cut manually at ground level and piled in the plot center.

In eight of the plots, cut woody material was

scattered into small piles within the plot.

This material

accounted for no more than 5% of the total cut material and these plots were not treated differently in subsequent analyses.

Within 20 days of cutting, woody material piled

in the plot center was burned completely.

All cutting and

burning occurred in January-March, generally with snow still on the ground. Post-treatment data were collected in August-September 1991, 1992, and 1993.

In each of the 16 plots, 11, 1.0 m2

permanent quadrats were located in a stratified random design; seven plots were located in cut-only areas and four were located in cut/burned areas.

In each quadrat, the

density and diameter at ground level of all woody stems > 10 cm tall and the mean height of the three dominant shrub species (V.corymbosum, N. mucronata, and A. melanocarpa) were recorded by the size classes indicated above.

A

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measure of mammalian herbivory was determined in December of 1991 in 40 1-m2 plots in cut only areas and 15 1-m2 plots in cut and burned areas by determining the number of browsed stems in each plot relative to the total number of stems and multiplying by 100.

Mammalian Herbivore Exclosures Eight additional plots were established in the winter of 1992 to study the effects of excluding browsing activity. Pre- and post-treatment vegetation measures in these plots were identical to the plots described above.

Woody material

was cut, piled in plot center, and burned as above.

A 5 x 5

m chicken wire fence 2.5 m high was constructed in each plot and situated so half of its coverage was in a burned-over area and half was in a cut-only area.

Herbicide Treatments An additional experiment was initiated to determine the effectiveness of several herbicide treatments in controlling vegetation in the Burn Area.

Herbicide treatments were

conducted on 23 September 1992 prior to the beginning of fall foliage color change. Treatments consisted of four replications of the following: 1) a single application of a 3% v:v solution of glyphosate (Rodeo, Monsanto Corporation) applied as a foliar spray at a mean distance of 0.3 m; 2) an identical application procedure followed by removal of standing stems,

62

cut at the base, two weeks after application; 3) removal of all woody stems by cutting at the base followed by wick application of 50% glyphosate to the cut stems; 4) removal of all woody stems by cutting at the base, without any herbicide treatment; and 5) no treatment. Plots were 5 x 5 m (25 m2) and arranged adjacent to each other in a 5 x 4 completely randomized design.

These

plots were located in the Burn Area and 100 m from plots described in the previous experiments.

Shrub seedling

(woody stems < 0.5 cm diameter at ground level) and stump sprout densities, live stem basal area, and percent mortality were measured in the center 1.0 m2 of each plot in August of 1993.

Percent mortality was calculated as the

number of dead treated stems/total number of treated stems x 100.

Small Mammal and Eastern Massasauga Abundance To assess the relative abundance and diversity of small mammals, the principal prey type of eastern massasaugas (Keenlyne and Beer 1973, Bielema 1973, Seigel 1986), a trapping program was conducted in the late summers of 1991, 1992, and 1993.

Six trapping stations, each consisting of

either two Museum Special snap traps or one snap trap and one pitfall trap were established in each of the 16 plots treated by cutting and burning.

In each plot, four of the

stations were randomly placed within the plot and two were placed within 1 m from the plot edge.

Snap traps were

63

baited with a mixture of rolled oats and peanut butter. Pitfall traps were unbaited and consisted of a 2 L plastic pail buried to its rim and placed against a log or a hummock edge.

Pitfall traps were 1/3 filled with water and

functioned as a drown trap.

Traps were opened for three

successive nights during each summer and checked daily. Each trapped animal was weighed and standard measurements were taken.

No attempt was made to sex or age trapped

animals. Another portion of the Burn Area, whose nearest border was 100 m from the treated plots, was selected where a similar trapping regime was conducted.

This area functioned

as a reference. To determine abundance available in other habitats at CSWMA, small mammals were sampled along 250 m transects in swamp forest habitat adjacent to the Burn Area in 1989 and 1992.

Three traps (one pitfall, one Museum Special and one

mouse trap) were placed in stations every 25 m along the transects. Due to their small population size and low probability of detection in CSWMA (Johnson 1995), direct assessment of eastern massasauga use of treated and untreated areas was not attempted.

A subset of eastern massasaugas captured at

CSWMA was taken from the field for intraperitoneal implantation of radiotransmitters, using a modification of the methodology of Reinert and Cundall (1982), for studies of spatial ecology and habitat use (Chapters 2 and 3).

The

64

proportion of aboveground radiolocations of these telemetered individuals within the Burn Area that occurred within treated areas was calculated.

Locations were only

counted if the individual moved at leat 5 m since its previous location.

Analytical Methods Fire and Cutting Treatments To evaluate the responses of woody species to the two treatments (cutting and cutting followed by burning), I calculated the frequency, relative frequency (RF), density, relative density (RD), basal area, and relative basal area (RBA) for each woody species, and the importance value [IV = (RF+RD+RBA)/3] for V. corymbosum, N. mucronata,

A.

melanocarpa and a category ("Other") that grouped the remaining shrub species.

The mean height of V. corymbosum,

N. mucronata, and A. melanocarpa was also measured. To evaluate the vegetative response within each year, one-way ANOVA (completely randomized block design with two treatments and 16 plots as blocks) was performed for each of the response variables: density of woody stems > 10 cm in height (STEMDEN), mean height of woody stems (HEIGHT), total basal area of woody stems > 10 cm in height (BASAL), and importance values of N. mucronata (IVNEMU), V. corymbosum (IVVACO),

A. melanocarpa (IVARME), and the

remaining woody stems (IVOTHER).

To reduce the probability

of a Type I error for simultaneous inference, the level of

65

significance (ÿ = 0.05) was adjusted to 0.01 (Bonferroni adjustment), the experimentwise type I error rate (Beal and Khamis 1991). To more fully investigate treatment effects over time, a 2 x 3 (treatment x year) factorial ANOVA using time as a repeated measures variable was performed on each response variable (Meredith and Stehman 1991).

Orthogonal polynomial

contrasts were generated to provide a description of the variable response curves over time.

SAS (SAS Institute Inc.

1990) was used for all statistical analyses.

Mammalian Herbivore Exclosures Repeated measures factorial (treatment x year) ANOVA with four treatments and eight experimental units (plots) was used to evaluate differences in the treatments containing herbivore exclosures.

The treatments were 1)cut

only without fencing, 2)cut only with fencing, 3)cutting followed by burning without fencing, and 4)cutting followed by burning with fencing.

Differences within treatments and

between years were examined using planned orthogonal contrasts. To examine the effects of time within each treatment, I ran separate one way ANOVAs (ÿ = 0.01) for each treatment for each response variable.

Plots were treated as blocks to

reduce the variation among different plots within a treatment.

66

Herbicide Treatments For each response variable, differences between the four treatments and control were tested by one-way ANOVA. When the overall F-test was significant, Tukey's HSD multiple comparison test was used to indicate which treatment was statistically significantly different from each other and the control.

Small Mammals The catch per unit effort, measured as the number of small mammals caught per 100 trapnight (TN), was calculated for each habitat and treatment type for each year. Chi-square goodness-of-fit tests and binomial tests (for small values of n, Zar 1984) were used to test for differences between capture rate in treated and untreated areas.

Total species richness and the Shannon-Wiener index

(H') were used as measures of small mammal diversity within treated and untreated areas.

RESULTS Fire and Cutting Treatments Descriptive statistics for shrub vegetation variables prior to treatment are presented in Table 4-1.

N. mucronata

and V. corymbosum are the two most important shrub species in the Burn Area, in terms of both coverage and density. For all measures but the importance value of A. melanocarpa and the importance value of all other woody species

67

combined, the coefficient of variation was less than 50%. Since the coefficient of variation is independent of the unit of measurement, this suggests that, for most of these measures of vegetation structure and composition of the two dominant shrub species, the Burn Area habitat is relatively homogeneous. This is not the case with canopy tree species found in the Burn Area (Table 4.2).

For all five species, density

and basal area are very variable across the plots.

P.

mariana was by far the most abundant canopy tree species. The means and standard errors of the response variables for the first three years following treatment are illustrated in Fig. 4-2. 1.

The values are given in Appendix

Stem density of all woody shrubs was higher in cut-only

plots ( = 64.56 stems/m2) than cut and burned plots ( = 41.48) for the first year following treatment only (F1,30 = 17.70; P = 0.0008, Table 4.3).

In subsequent years, there

were no observed significant differences between treatments. Similarly, shrub basal area shows the same year-to-year pattern, where differences were only detected in 1991 (F1,30 = 22.82; P = 0.0002, Table 4.3) and mean basal area was higher in the cut only treatment. Shrub height differs significantly between the two treatments in all three years (F1991 = 128.65, F1992 = 126.17, F1993 = 48.57; Pall three years = 0.001; df = 1,30, Table 4.3).

Stem height was always lower in plots that were

cut and burned.

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There were no treatment differences detected between the importance values of Nemopanthus, Vaccinium or Aronia within any year (Table 4.3), however the importance value of all other shrub species combined was significantly greater in the cut only areas ( = 10.17) than the cut and burned areas ( = 6.14) at the end of the first growing season (F1,30 = 9.74; P = 0.007). Repeated measures ANOVA with orthogonal polynomial contrasts shows the effect of time and treatment on these measures (Table 4.4).

The interaction of time and treatment

was significant for stem density (F = 7.05, P