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cockatoos (Calyptorhynchus latirostris, C. baudinii and C. banksii naso). Mean retention times for the transmitter packages ranged from 44 to 384 days.
Retention of transmitter attachments on black cockatoos (Calyptorhynchus spp.) ANNA T. LE SOUËFA,F, DEJAN STOJANOVICB,E, ALLAN H. BURBIDGEC, SIMONE D. VITALID, ROBERT HEINSOHNE, RICK DAWSONC and KRISTIN S. WARRENA Despite the widespread use of telemetry to track the movements of many different avian species, there are few published studies describing tracking methods for large psittacine birds. Due to their powerful bills and inquisitive demeanours, large parrots may damage valuable transmitters and confound telemetry studies. We undertook a captive trial of three attachment methods (collar, harness and tail-mount) and a novel weak-link harness design for black cockatoos (Calyptorhynchus latirostris, C. baudinii and C. banksii naso). Mean retention times for the transmitter packages ranged from 44 to 384 days. There was no skin or feather damage to the birds associated with transmitter attachments. The results showed sufficient transmitter retention times to allow for the collection of valuable movement and survival data, with no obvious ill effects on animal welfare, and are a first step towards using transmitters on wild cockatoos.

INTRODUCTION

OF the 355 extant psittacine species recognized

by BirdLife International, 39% are listed as being near threatened to critically endangered, making parrots one of the most threatened groups of birds (BirdLife International 2011). Habitat alteration is the major threat, impacting a broad range of species, including several species of Australian black cockatoos (Calyptorhynchus spp.) (Forshaw and Knight 2010, Garnett et al. 2011). Despite extensive research into some aspects of their life histories, a lack of knowledge about habitat use and landscapescale movements of black cockatoos impedes effective management strategies for most species (Davies 1966, Saunders 1980, Cameron 2006, Chapman 2007). Telemetry units have been used to provide detailed information on the movements, habitat use and life history of many bird species, including some parrots (Elliott et al. 1996, Meyers 1996, Myers and Vaughan 2004, White et al. 2005), however the powerful bills and allopreening behaviour of larger species like cockatoos may be a major impediment to retention of external devices (Saunders 1979, 1980, Nelson and Morris 1994, Higgins 1999, Cooper et al. 2002, Cameron 2006). Further, externally attached transmitting devices can

impose physiological or behavioural costs on the study subject (Hines and Zwickel 1985, Gessaman and Nagy 1988, Massey et al. 1988, Obrecht et al. 1988, Longcore et al. 2000, Iverson et al. 2006, Vukovich and Kilgo 2009), so evaluating transmitter effects is important in advance of field deployment. Here, we report the results of a trial of six transmitter types and three attachment methods on captive black cockatoos to investigate the feasibility of deploying transmitters on wild black cockatoos. METHODS Study area and species We used 17 Carnaby’s Cockatoos (Calyptorhynchus latirostris), six Baudin’s Cockatoos (C. baudinii) and six Red-tailed Black Cockatoos (C. banksii naso) (Table 1) at the Kaarakin Black Cockatoo Rehabilitation Centre in Martin, Western Australia. Most birds used (n = 22) were capable of normal flight. All birds were housed in three aviaries (two were 12 m × 5 m × 2.5 m high and one was 6 m × 3.5 m x 2.5 m high) fitted with hollow logs and artificial nest boxes. Seed, water and native browse were available ad libitum.

Table 1. Number of black cockatoos of each species assigned to different transmitter groups. Transmitter type

Carnaby’s Black-Cockatoo

Baudin’s Black-Cockatoo

Red-tailed Black Cockatoo

Collar Tail-mount (6g) Tail-mount (12g) Harness (12g) Harness (16g) Harness (20g)

3 2 3 3 3 3

2 2 0 0 1 1

1 2 0 1 0 1

Conservation Medicine Program, School of Veterinary and Life Sciences, Murdoch University, WA 6150, Australia Bird Life Western Australia, 167 Perry Lakes Drive, Floreat WA 6014, Australia Department of Environment and Conservation, PO Box 51, Wanneroo WA 6946, Australia D Veterinary Department, Perth Zoo, 20 Labouchere Road, South Perth, WA 6151, Australia E Fenner School of Environment and Society, Australian National University, ACT 2601, Australia F Corresponding author. Email: [email protected] A

B

C

PACIFIC CONSERVATION BIOLOGY Vol. 19: 55–57. Surrey Beatty & Sons, Sydney. 2013.

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PACIFIC CONSERVATION BIOLOGY

Transmitter attachment We tested two tail-mounted radio Platform Transmitter Terminals (PTTs) weighing 6 g (n = 6) and 12 g (n = 3) (Sirtrack Wildlife Tracking Solutions, Havelock, New Zealand), three harness-mounted solar PTTs weighing 12 g (n = 4), 16 g (n = 4) and 20 g (n = 5) (North Star Science and Technology, Virginia, USA); and a radio collar weighing 24 g (n = 7) (Holohil Systems Ltd., Ontario, Canada). Transmitters were fitted to the birds under isoflurane gaseous anaesthesia, to reduce stress from handling. The maximum weight of our transmitters was 4 % of body mass, which is below the maximum weight typically used in birds (Gessaman and Nagy 1988, Kenward 2001, Godfrey et al. 2003). An ‘X-attachment’ method (Buehler et al. 1995) was modified for the harness design, incorporating a single weak link. Neoprene pads were glued to the base of the PTTs to reduce abrasion and to raise the solar panels above the feathers. Teflon ribbon (Telonics Inc., Mesa, Arizona, USA) was used to form the harness and position the unit between the scapulae so that cranial and caudal movement was limited to 0.5 cm (Buehler et al. 1995). Harnesses were secured with absorbable suture material where the four ribbons met at the sternum (the ‘weak link’) and sealed with glue to prevent fraying. The 12 g tail-mounted PTT was attached dorsally to the two central feathers using nylon fishing line and cyanoacrylate glue and the antenna was tied and glued along its length to one tail feather. The 6 g tail-mounted PTT was attached in the same way but to the ventral surface of the tail feathers. Collars were attached with the barrel resting above the sternum and bolted in the middle tightness setting, with approximately 1 cm of space between the collar and the neck. ‘Retention time’ was defined as the point when the transmitter package was either damaged enough to impair transmission or was no longer attached to the bird. At the end of the study (554 days) any transmitters were removed that had not already failed and differences in mean retention time were compared between transmitter packages. Physical examinations of feathering, skin and general body condition were carried out one week following attachment, then at monthly intervals for 12 months, for any physical effects on the birds from the transmitters. Statistical analyses Analyses were performed using SPSS version 17.0 for Windows (SPSS Inc., Chicago, Illinois). Data were tested for normality using a ShapiroWilk test. A Kruskal-Wallis test was used to

compare retention times between groups, using transmitter attachment method (collar, tailmount or harness) as the grouping variable and retention time (days) as the dependent variable. When a significant difference (p < 0.05), was detected a Mann-Whitney test was used to make pairwise comparisons. RESULTS In this study, retention times varied significantly among attachment method (χ2(2) = 7.14, p = 0.026). Collars were retained significantly longer than tail-mounts (p = 0.027) and harnesses (p = 0.046), with no statistical difference between the mean retention times of tail-mounts and harnesses (p = 0.126). Table 2. Transmitter retention times (days) for collar, 12 g tail-mount, 6 g tail-mount, 12 g harness, 16 g harness and 20 g harness transmitter packages on black cockatoos. Transmitter type

n

Retention time (days) Range ¯x

S.E.

Collar Tail–mount (12 g) Tail–mount (6 g) Harness (12 g) Harness (16 g) Harness (20 g)

6 6 3 4 4 5

1–554 29–75 1–287 7–246 29–365 7–554

90 15 45 57 94 103

447 44 71 113 202 206

There was no evidence of skin irritation or feather wear underneath the transmitter attachments at the monthly physical checks. Although behaviour was not analysed, there were no other obvious changes to behaviour, flight or gait in the birds studied. Causes of transmitter failure included destruction due to chewing by the cockatoo (n = 7), spontaneous detachment from the cockatoo (n = 4) and manual removal by the authors due to a loose thread (n = 1). All collars remained attached for the study, except for one that was removed immediately by the authors after a Baudin’s Black-Cockatoo entangled its lower bill in the collar. Tail-mounts failed due to chewing by the cockatoo (n = 2) or spontaneous detachment (n = 7). DISCUSSION Our data suggest that some telemetry attachments may be suitable for large psittacine birds with strong bills. In particular, tailmounted attachments are suggested for telemetry studies, as they are likely to present the lowest snagging risk to the bird, while still having retention periods in our study of up to 287 days. We did not observe snagging with harnesses, but this attachment method has been associated with higher risks than tail-mounted packages (Kenward 2001). Retention times for transmitters were highly variable and in part, reflect individual reactions

LE SOUËF et al: RETENTION OF TRANSMITTER ATTACHMENTS ON BLACK COCKATOOS

of birds to the attachments. Cockatoos damaged nine of 29 transmitter units and such attrition rates should be anticipated when planning tracking studies on these birds. Some birds seemingly ignored their attachments, with one Red-tailed Black-Cockatoo laying and incubating an egg in a hollow log while wearing a harnessmounted PTT. Although the sample size precluded statistical comparison between species, Red-tailed Black-Cockatoos (which have considerably larger bills than the other species) were noted to inflict the greatest bite damage to both harness and tail-mounted packages. Also, the longer, slender bill shape of the Baudin’s Black-Cockatoo may predispose this species to entanglement with collars, which occurred with one bird in this study. Testing transmitter attachments on captive birds has the advantage of allowing detailed observation of transmitter retention. This study is a first step towards further research into the habitat preferences and movements of black cockatoos using telemetry. ACKNOWLEDGEMENTS We thank S. Mason, T. Stadler, Murdoch University, Birdlife Australia, WWF-Australia and Perth Zoo for funding this research, and C. Holyoake, M. Calver and I. Robertson for comments on earlier drafts. We gratefully acknowledge the financial support provided by Newmont Boddington Gold towards Dr Anna Le Souëf ’s position as Research Fellow, Black Cockatoo Health and Demographics Project. The Western Australian Department of Environment and Conservation (DEC), the Kaarakin Black Cockatoo Rehabilitation Centre and numerous volunteers helped with the study. The research was approved by the Murdoch University Animal Ethics Committee (NS2116/07), Perth Zoo Animal Ethics Committee (2008–9) and the DEC (Regulation 17 Licence SF006743). REFERENCES BirdLife International, 2011. The BirdLife checklist of the birds of the world, with conservation status and taxonomic sources. Version 4. http://www.birdlife.info/ im/species/checklist.zip. 8 September. Buehler, D., Fraser, J., Fuller, M., McAllister, L. and Seegar, J., 1995. Captive and field-tested radio transmitter attachments for bald eagles. J. Field Ornithol. 66: 173–180.

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