An inexpensive satellite-download GPS receiver for wildlife: field trial on black swans

Abstract

Context Knowledge of the movements and space-use patterns of wildlife is crucial for implementation of effective conservation and management actions. Such information can be difficult to obtain, especially from hard-to-capture or far-ranging taxa. Global-positioning-system (GPS) receivers that have remote data-acquisition capability via satellite-communication networks offer an effective means of tracking highly mobile animals; however, often the equipment and operational costs of these devices are prohibitive. Aim To evaluate the operational performance and potential of an inexpensive, commercially available satellite-download GPS receiver that can be easily modified for use on wildlife, and to demonstrate its utility for revealing novel information on individual animal movements in an important wildlife management context. Methods We added external batteries and supplementary waterproofing to ‘off-the-shelf’ SPOT Trace® GPS receivers (~$120 USD; Spot LLC, Covington, LA) that transmit recorded location data to users through the Globalstar satellite network. We then deployed these devices on eight wild black swans (Cygnus atratus) inhabiting a large inland marine harbor adjacent to Auckland International Airport and assessed the GPS units’ operational performance and overall cost effectiveness. Key results During field trials with the tracking devices lasting up to 25 days we were able to collect thousands of precision location observations from the swans without the need for recapture. Cost-per-fix was only ~$0.04 USD – up to an order of magnitude lower than some satellite-download GPS receivers manufactured specifically for wildlife. We provide novel information about the swans’ patterns of activity, movement, space-use, habitat preferences and responses to actions taken by airport staff to scare problem individuals from threat zones. Conclusions User-modified satellite-download GPS devices can be a highly cost-effective means of tracking the movements of animals. Implications Knowledge of where and when swans present the greatest likely threat to air traffic and how they respond to displacement from restricted areas near the airport will be useful in devising threat-management plans. The ready availability of affordable remote-download GPS receivers will provide many new opportunities to study the movement and/or space-use patterns of wildlife and incorporate such information into a broad range of research and management programs.