1Department of Biology, Box 351800, University of Washington, Seattle, Washington 98195-1800, USA ... Argentina, using an automated detection system.
Journal of Field Ornithology J. Field Ornithol. 80(4):408–418, 2009
DOI: 10.1111/j.1557-9263.2009.00248.x
Flipper bands do not affect foraging-trip duration of Magellanic Penguins P. Dee Boersma1,2,3 and Ginger A. Rebstock1,2 1
Department of Biology, Box 351800, University of Washington, Seattle, Washington 98195-1800, USA 2 Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York 10460, USA Received 6 February 2009; accepted 27 July 2009
ABSTRACT. Flipper bands are used to mark penguins because leg bands can injure their legs. However, concerns remain over the possible effects of flipper bands on penguins. We examined the effects of stainless-steel flipper bands on the duration of foraging trips by Magellanic Penguins (Spheniscus magellanicus) at Punta Tombo, Argentina, using an automated detection system. We predicted that, if bands were costly and increased drag, flipperbanded penguins would make longer foraging trips than those with small or no external markings. We tagged 121 penguins with radio-frequency identification (RFID) tags and an additional external mark. We placed either a stainless-steel band on the left flipper (N = 62) or a 2×10-mm small-animal ear tag in the outside web of the left foot (N = 59). We measured foraging-trip durations (N = 376 trips) for 68 adult penguins with chicks from 15 December 2007 to 28 February 2008. Contrary to predictions, trip duration was similar for banded and web-tagged penguins (P = 0.22) and for males and females (P = 0.52), with no interaction between tag type and sex (P = 0.52). No penguins marked in the 2007 breeding season and recaptured between 30 September and 30 November 2008 (N = 113) lost flipper bands or web tags, but three RFID tags failed between March and September 2008. Properly designed and applied flipper bands were a reliable marking method for Magellanic Penguins, had a lower failure rate than RFIDs, and did not affect foraging-trip duration. ´ de viajes para forrajeo por Spheniscus RESUMEN. Los anillos de ala no afectan a la duracion magellanicus Los anillos de ala son usados para marcar ping¨uinos porque los anillos de tarso pueden causar heridas en sus piernas. Sin embargo, existen dudas sobre los posibles efectos de los anillos de ala sobre los ping¨uinos. Usando un sistema de detecci´on automatizado, examinamos los efectos de anillos de ala hechos de acero inoxidable sobre la duraci´on de los viajes para forrajeo por el ping¨uino Spheniscus magellanicus en Punta Tombo, Argentina. Predecimos que si los anillos afectar´ıan a los ping¨uinos e incrementaran la fricci´on con el agua, los ping¨uinos con anillos de ala har´ıan viajes para forrajeo de mayor duraci´on en comparaci´on a los que no portaban marcadores externos o que llevaban marcadores externos de menor tama˜no. Marcamos a 121 ping¨uinos con marcadores de identificaci´on por radio frecuencia, adem´as de otro marcador al exterior del ave. Colocamos un anillo de acero inoxidable al ala izquierdo (N = 62), o un marcador de oreja (2×10 mm) para animales peque˜nos de en la membrana interdigital exterior del pie izquierdo (N = 59). Desde el 15 de diciembre del 2007 hasta el 28 de Febrero del 2008 medimos la duraci´on de los viajes para forrajeo (N = 376 viajes) para 68 ping¨uinos adultos con pichones. Contrariamente a nuestras predicciones, la duraci´on de los viajes fue similar para ping¨uinos con anillos y para ping¨uinos con marcadores en el pie (P = 0.22), as´ı como entre machos y hembras (P = 0.52), con ninguna interacci´on entre el tipo de marca y el sexo (P = 0.52). Ning´un ping¨uino marcado en la temporada reproductiva del 2007 y recapturado entre el 30 de Septiembre y el 30 de Noviembre del 2008 (N = 113) perdi´o el anillo de ala o el marcador en el pie, pero tres marcadores de identificaci´on por radio frecuencia fallaron entre Marzo y Septiembre del 2008. Los anillos de ala apropiadamente dise˜nadas y aplicadas fueron un m´etodo de marcaje confiable para S. magellanicus, tuvieron una tasa de fallo menor a los marcadores de identificaci´on por radio frecuencia y no afectaron a la duraci´on de los viajes para forrajeo. Key words: band effects, flipper band, foraging-trip duration, Magellanic Penguin, radio-frequency, Spheniscus magellanicus
Banding penguins allows individual identification, but flipper bands of earlier designs sometimes injured birds (Jarvis 1970, Sallaberry and Valencia 1985). Band location and design 3 Corresponding washington.edu
C 2009
author.
Email:
boersma@u.
evolved to reduce the negative effects, but the costs to penguins of wearing a flipper band continues to be debated (Stonehouse 1999, Jackson and Wilson 2002, Petersen et al. 2005a). Even well-designed bands that do not injure penguins may affect penguin foraging behavior (Dugger et al. 2006), colony attendance and reproductive success (Froget et al. 1998,
C 2009 Association of Field Ornithologists The Author(s). Journal compilation
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Bands and Trip Duration of Magellanic Penguins
Gauthier-Clerc et al. 2004), or survival (Dugger et al. 2006). These effects are thought to be caused by increased drag during swimming. For example, banded Ad´elie Penguins (Pygoscelis adeliae) used 24% more energy than unbanded penguins (Culik et al. 1993) to swim in a tank. However, studies of the costs of bands have not produced consistent results (Petersen et al. 2005b, Dugger et al. 2006, Hampton et al. 2009). Band material, design, application, and placement often vary among studies, and these variables may affect the costs of wearing bands. Variation in flipper shape and size within and among species may also result in differences in the impacts of bands (Sladen and Penney 1960). However, band design, particularly whether they have protruding locking mechanisms (Cooper and Morant 1981, Sallaberry and Valencia 1985), is likely to cause the greatest differences in band effects. Not only are bands of unequal quality, but the method of application can have important consequences. Training personnel who band penguins is critical for correct application (Fraser and Trivelpiece 1994). In the most extreme cases, application of bands may kill penguins if there is insufficient room for the flippers to swell during molt (Ainley et al. 1983). In a study on Seal Island in the Antarctic, bands were placed upside down on several thousand penguins (J. Bengston pers. comm.), likely killing many penguins (D. Croll, pers. comm.). Foraging-trip duration may be useful in detecting the effects of bands. If bands cause increased drag during swimming, penguins should take longer to reach foraging areas and expend more energy. For example, foraging trips of Ad´elie Penguins with flipper bands were about 3.5 h (∼8%) longer than those of penguins without flipper bands (Dugger et al. 2006). Satellite transmitters, especially those that are large relative to the size of the penguins, can also increase foraging-trip duration (Wilson et al. 1989, Hull 1997, Taylor et al. 2001, RopertCoudert et al. 2007). However, some investigators have not reported increased trip duration for penguins with satellite transmitters (Hull 1997, Ballard et al. 2001), probably because of differences in transmitter size, shape, and antennae (Wilson et al. 1986, Culick et al. 1994, Wilson et al. 2004). Effects of bands and attached instruments need to be minimized not
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only because of ethical concerns, but also because the results of experiments or observations of banded or instrumented penguins may not be representative of the behavior of penguins without external marks or instruments. The effect of bands may also vary with sex. Male penguins are generally larger than females (Williams 1995). Smaller females may be more susceptible to the effects of band-induced drag than males, whereas larger males may be more likely to be injured by restricted circulation when flippers swell during molt if bands are too tight. Since 1983, we have marked Magellanic Penguins (Spheniscus magellanicus) with stainlesssteel flipper bands that we custom fit to each penguin at Punta Tombo, Argentina (Boersma et al. 1990). Similar bands have been used to mark African Penguins (S. demersus) since the 1980s (Cooper and Morant 1981). Loss of stainlesssteel bands is rare, as is direct damage caused by the bands. Nonetheless, we wanted to determine if we were missing possible negative impacts of the bands. We quantified the impact of stainlesssteel bands on the duration of foraging trips by breeding Magellanic Penguins with a radiofrequency identification (RFID) tag and either a flipper band or a small (2 × 10 mm) tag in the webbing of the foot. We also equipped some penguins with satellite transmitters and examined the effect of these devices on trip duration. Our objectives were to determine if: (1) the foraging trips of penguins with flipper bands were longer in duration than those of penguins with web tags, (2) differences in foraging-trip duration for penguins with and without flipper bands were greater for females than males, and (3) the foraging trips of banded penguins with satellite transmitters were longer in duration than those of banded penguins without satellite transmitters. METHODS Penguin tags. We used two types of external tags and internal RFID tags (Fig. 1) on Magellanic Penguins at Punta Tombo, Argentina (44◦ 3’S, 65◦ 13’W). Tags were applied between 7 December 2007 and 2 January 2008, except for five males and three females at seven nests that were banded between 1992 and 2002. Flipper bands (Figs. 1A, C) were designed by PDB and made of stainless steel (LambournesPorzana, East Sussex, UK). These bands are
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J. Field Ornithol.
Fig. 1. Identifying tags used on Magellanic Penguins at Punta Tombo, Argentina. (A) Flipper band on left flipper of an adult Magellanic Penguin. (B) Web tag on left foot of a Magellanic Penguin chick. (C) RFID tag (left), web tag (center), and flipper band (right). The web tag is open, prior to attachment. The pointed end pierces the webbing, goes through the hole in the opposite end, and folds over to lock. The flipper band is closed as it would be on a penguin. Note the tear-drop shape and overlapping ends. A, B, and C are not to the same scale.
tear-drop-shaped and the ends overlap, allowing each band to be individually fitted to the penguin using custom-made banding pliers. The bands overlapped less for large males than for small females. The bands are 34 mm long by 17–20 mm at the widest part, are 12 mm high and 1 mm thick, and are stamped with a 5-digit identification number. Web tags ( Figs. 1B, C) were attached to the outer webbing (between the middle and outside toes) of the left foot. When penguins swim, they
use their flippers to propel themselves, not their feet. The feet trail behind the penguin acting as rudders with the web tag in the folds of the web. We used self-piercing, numbered, small-animal ear tags (#1005–3, 2 × 10 mm; National Band and Tag Company, Newport, KY). Because of their small size, web tags cannot be read from a distance and penguins were captured to read the tags. In some cases, especially if a tag was dirty, we cleaned the tag with water and used a magnifying glass to read the numbers. Because of
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Table 1. Pairs of Magellanic Penguins at 61 nests were given an RFID tag and either a flipper band or a web tag. No. Nests of with Female Male nests chicksa Bandb Web tag 29 21 Web tagb Band 30 24 Band 1 0 Bandc N/A 1 0 Bandd a The number of nests with chicks still alive after 10 January. b At 59 nests, one member of the pair was given a flipper band and the other a web tag. c At one nest, both penguins had been previously banded. d At one nest, we banded the female, but could not capture the male to tag. N/A = not applicable.
their small size and placement, we assumed that web tags caused little, if any, drag and that the energetic cost to a penguin was negligible. If web tags do have any effect on swimming penguins, it should be smaller than that of flipper bands, so we used web-tagged penguins as a control group. In 26 yr of studying penguins, we have not seen a foot swollen or infected by a web tag. In addition, web tags attached 15 yr ago and flipper bands attached more than 25 yr ago looked similar to when they were first applied. Bands do sometimes open, usually less than 5 mm, and, when we observed an open band, we captured the penguin and closed the band. We externally marked all penguins in this study so we could quantify RFID-tag loss and failure rates. RFID tags (Fig. 1C) were injected just under the skin in the lower left tarsometatarsus of 121 penguins and the injection site was sealed with tissue adhesive (Vetbond; 3M, St. Paul, MN). RFID tags (134.2 kHz; Agrident GmbH, Barsinghausen, Germany) measured 12 mm × 2.1 mm in diameter. Both members of each pair received an RFID tag; one member also received a flipper band (N = 62) and the other a web tag (N = 59). We alternated giving flipper bands to males and females in each nest (N = 61 nests; Table 1). Sex was determined using bill measurements, with the larger billed bird being the male. We chose the tarsometatarsus for
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the implantation site because it is close to the ground, facilitating reading by the antennae. Other possible locations, such as the back and face, receive frequent pecks, bites, and hits from flippers when penguins fight, causing RFID breakage. We observed penguins walking after RFID-tag implantation and penguins with and without tags walked similarly. We assumed swimming was also unaffected. In addition to flipper bands and RFID tags, six males were fitted with satellite transmitters (Telonics ST-20, Mesa, Arizona; packaged by Sirtrack, New Zealand). Satellite transmitters were approximately 9.7 cm long by 3.7 cm wide by 1.8 cm high and weighed 95 g. Nests where males had satellite transmitters were checked twice a day; other nests were checked every 10 d. Automatic monitoring system. We installed an automatic detection system (Beigel Technology, Encinitas, CA) that read RFID tags from 9 December 2007 to 4 April 2008. The system contained two antennae to read RFID tags and indicate the direction the penguins walked, either toward the beach or toward the nests. The antennae consisted of copper wire coiled inside closed-cell foam pads. Coils were 3 m long by 0.5 m wide. The antennae were connected to a computer that logged the IDs and times of reading by each antenna. The computer was sealed in a weather-proof box and the system was powered by solar panels. The foam pads containing the antennae were placed on the ground parallel to each other, 0.5 m apart, across a dry stream bed, where many penguins were funneled into a narrow path when they walked between the beach and their nests. Nests were not fenced and penguins were not constrained to cross the antennae to reach their nests if they chose to take another route. When the pads were first deployed, penguins hesitated to cross them, but soon crossed the pads readily. Nests were approximately 70–265 m from the RFID readers. Penguins may sometimes have walked over the pads in one direction and then walked around them in the other direction, resulting in a certainty
