Retention, Effect, and Utility of Tail-mounted Satellite-tracked Transmitters on Golden Eagles

Abstract Studies deploying Platform Transmitter Terminals (PTTs) or Global System for Mobile Communications-GPS (GSM) packages on Golden Eagles have typically used backpack harnesses for attachment despite evidence indicating potential significant negative effects on reproduction and survival. Retention, safety, and utility of tail-mounted PTTs were tested on a sample of Golden Eagles in southwestern Montana. Argos satellite-tracked PTTs of two configurations were attached dorsally or ventrally to the central rectrices of 27 Golden Eagles to study survival. Sixteen packages were known to have been molted or removed (i.e., shed) by the eagle and 13 recovered. Of recovered tail-mounts, six (46%) were forcibly removed by eagles; five by males and one by a female. All packages that were forcibly removed were 32-g ventral mounts. Females tended to retain tail-mounts longer than males and dorsally mounted PTTs tended to be retained longer than those mounted ventrally. Eagles tagged in winter retained PTTs the l...