Journal of the Royal Society of New Zealand abstracts

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Mortality of radio-tracked wild rats in relation to transmitter weight and resilience of transmitters in relation to their design

Jörn Theuerkauf¹, Sophie Rouys², and Clémence Chatreau³

¹Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679, Warsaw, Poland. jtheuer@miiz.waw.pl

²Marine Laboratory for Environmental Resource Studies, University of New Caledonia, B.P. 4477, 98847 Nouméa Cedex, New Caledonia. rouys@ifrance.com

³Conservation Research New Caledonia, B.P. 2549, 98846 Nouméa Cedex, New Caledonia. clemence.chatreau@free.fr

Abstract We assessed mortality of rats in relation to transmitter weight and tested several types of rat transmitters in order to provide recommendations for their design. We used 21 collars with radio- or dummy transmitters, made of either epoxy or dental acrylic, with external or internal (inside the collar) antennae, on 20 rats (Rattus rattus and R. exulans) in rainforests of New Caledonia. We found that rats chewed and destroyed most external whip antennae and transmitters made of epoxy. Rats, especially males during the reproductive season, with transmitters that weighed 4.7–7.1% of their body weight, had a higher mortality than those with transmitters that weighed 2.1–4.0% of their body weight. We recommend keeping transmitter weight down to about 4% of body weight, constructing transmitters exclusively of dental acrylic and using internal antennae if their heavier weight and lower range do not cause problems for the study.

Keywords    predation risk; radio-tracking; Rattus; rodent; survival; transmitter weight

R06016; Received 12 October 2006; accepted 30 July 2007; Online publication date 17 August 2007

Journal of the Royal Society of New Zealand
Volume 37, Number 3, September, 2007, pp 85–90

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