Abstract
BackgroundSatellite telemetry studies provide information that is critical to the conservation and management of species affected by ecological change. Here we report on the performance and retention of two types (SPOT-227 and SPOT-305A) of ear-mounted Argos-linked satellite transmitters (i.e., platform transmitter terminal, or PTT) deployed on free-ranging polar bears in Eastern Greenland, Baffin Bay, Kane Basin, the southern Beaufort Sea, and the Chukchi Sea during 2007–2013.ResultsTransmissions from 142 out of 145 PTTs deployed on polar bears were received for an average of 69.3 days. The average functional longevity, defined as the number of days they transmitted while still attached to polar bears, for SPOT-227 was 56.8 days and for SPOT-305A was 48.6 days. Thirty-four of the 142 (24%) PTTs showed signs of being detached before they stopped transmitting, indicating that tag loss was an important aspect of tag failure. Furthermore, 10 of 26 (38%) bears that were re-observed following application of a PTT had a split ear pinna, suggesting that some transmitters were detached by force. All six PTTs that were still on bears upon recapture had lost the antenna, which indicates that antenna breakage was a significant contributor to PTT failure. Finally, only nine of the 142 (6%) PTTs—three of which were still attached to bears—had a final voltage reading close to the value indicating battery exhaustion. This suggests that battery exhaustion was not a major factor in tag performance.ConclusionsThe average functional longevity of approximately 2 months for ear-mounted PTTs (this study) is poor compared to PTT collars fitted to adult female polar bears, which can last for several years. Early failure of the ear-mounted PTTs appeared to be caused primarily by detachment from the ear or antenna breakage. We suggest that much smaller and lighter ear-mounted transmitters are necessary to reduce the risk of tissue irritation, tissue damage, and tag detachment, and with a more robust antenna design. Our results are applicable to other tag types (e.g., iridium and VHF systems) and to research on other large mammals that cannot wear radio collars.
Highlights
Satellite telemetry studies provide information that is critical to the conservation and management of species affected by ecological change
We explored seasonal differences in performance of satellite transmitter (SPOT)-227 platform transmitter terminal (PTT) deployed during spring and autumn using the US PTTs, because 9 of 10 of the autumn PTTs were deployed in the USA
Based on a sample of 145 ear-mounted PTT tags deployed on free-ranging polar bears, factors accounting for failure of the transmitters were grouped into three categories: (1) loss of the transmitter from the bear, (2) antenna breakage, and (3) battery life
Summary
Satellite telemetry studies provide information that is critical to the conservation and management of species affected by ecological change. Estimates of apparent survival rates, which can reflect emigration from the study area, often differ between subadult and adult bears [12], suggesting that spatial patterns for polar bears may be related to age (e.g., that subadult bears are more likely to disperse to new areas). Given these potential sex- and age-related differences in movement, there is a need for more information on movement of adult male polar bears and subadults of both sexes, to accurately document the ecology of this species and its response to environmental change. There is a continuous interest in developing satellite tracking devices that are smaller, less visible, and potentially less cumbersome than radio collars [4, 13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
