Small radiotransmitters, powered by lithium batteries or solar cells a
nd epoxied to cattle ear tags, were attached to the interdigital webbi
ng of a hind foot on 75 California sea otters (Enhydra lutris nereis).
Observations of 54 otters that stayed in the California coastal study
area beyond expected battery life (60 days) indicated that tags with
radios were retained for greater than or equal to 263 days on average.
Radiotags damaged flipper webbing in 34% of 53 otters observed after
tags were attached. This tag design is easily applied when short-term
monitoring is needed and offers a functional alternative when intraper
itoneal-implanted transmitters are not advised.