An expandable radiocollar for black bear cubs

Reliable estimates of first-year survival of black bears (Ursus americanus) are largely unavailable because a technique to attach a telemetry device that can accommodate the rapid growth of black bear cubs has not been perfected. We designed and tested an expandable radiocollar on 47 cubs in 23 litters (20M:27F). Cubs wore radiocollars for an average of 132 days (1-268 days). Twenty of 47 (43%) cubs wore functioning radiocollars from their first denning period to the next or until their death. The remaining collars slipped prematurely (n=25) or the collar battery failed prematurely (n=2). No mortalities appeared to be related to the collar or its design, although we observed some minor injuries.