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1 November 2004 Evaluation of subcutaneous implants for monitoring American black bear cub survival
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Implanting radiotransmitters in wild animals to monitor physiological processes and survival rates is an accepted practice, but the degree of success for subcutaneous implants rarely has been reported, making it difficult to improve the practice of and equipment for subcutaneously implanting transmitters. We implanted radiotransmitters subcutaneously in 42 (21M:21F) wild American black bear (Ursus americanus) cubs from 2 study areas in Virginia during 1996–1999. We monitored the cubs from the date of implantation until the implants fell out, the cubs died, the transmitters failed or became undetectable, or until the cubs denned as yearlings the following den season. We removed 3 animals from our analysis because we judged that their fates were unrelated to the implants. Over 64% (25 of 39) of implants fell out or were rejected prematurely (2–198 days), 23% (9 of 39) presumably failed for unknown reasons, 5% (2 of 39, part of the previous 9) failed and were worn to the following den season, and 1 of 39 bears died less than 1 month after implant surgery. Only 10% (4 of 39) of implanted black bear cubs wore working transmitters to the following den season. We estimated an overall implant survival estimate of 6.5% for the implants. Our success was very limited using subcutaneous implants, but this can be improved through improvements in the surgical procedures, further miniaturization of transmitters and batteries, impermeable transmitter packages, and better understanding interactions among family members following implant surgery.

Kim N. Echols, Michael R. Vaughan, and H. David Moll "Evaluation of subcutaneous implants for monitoring American black bear cub survival," Ursus 15(2), 172-181, (1 November 2004).<0172:EOSIFM>2.0.CO;2
Received: 9 May 2001; Accepted: 1 April 2004; Published: 1 November 2004

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