Northern Prairie Wildlife Research Center
Catherine J. Henry, Mindy Hetrick, U.S. Fish and Wildlife Service, Commerce City, CO 80022 USA, Bruce Vander Lee, University of Wisconsin, Madison, WI 53706 USA, and Sherry Skipper, Clemson University, Pendleton, SC 29670 USA
Methods of attaching radio transmitters to small passerine birds have been reported with advantages and disadvantages. Rappole and Tipton (1991) described a figure-8 leg harness that was successful on thrushes and several other species. We conducted radio telemetry from 1994 to 1996 on American robins (Turdus migratorius), black-billed magpies (Pica pica), European starlings (Sturnus vulgaris), and house finches (Carpodacus mexicanus) on the Rocky Mountain Arsenal National Wildlife Refuge, Colorado, to assess exposure to contaminated soil. The leg harness was used on all four species. These studies were not designed specifically to evaluate the radio transmitter attachment method, but provided the opportunity to report on the successes and failures of harness materials, length of attachment, anecdotal behavior information, and manpower/time associated with field attachment. Materials that were successful on robins were 1-mm diameter elastic thread and hollow plastic fly-tying body material. None of the 27 male and 26 female robins were known to have lost transmitters during the approximate 80-day life of the transmitter. Fourteen robins returned in subsequent years with transmitters still attached. Four were recaptured and showed no adverse signs of wear or injury from the harness or transmitter. Starlings were able to bite through elastic thread and plastic material, but 4-mm wide teflon ribbon worked successfully for retention for the 80-day life of the transmitter on both adult and juvenile birds. It was presumed that magpies would also bite through most types of harness materials, therefore, teflon ribbon was used initially and was successfully retained. Only one of 36 (2.8%) adult magpies lost a transmitter within an 80-day period during the breeding season. No juvenile magpies (n = 42) lost transmitters during the first 50 days following fledging. During the following winter, one adult and one juvenile magpie were recaptured with their transmitters and showed no adverse signs of wear. House finches bit through elastic thread, but braided nylon fishing line harnesses remained on for the 25-day transmitter life in greater than 90% of applied transmitters (n = 55). Several finches were recaptured and showed no adverse impacts from harnesses. Visual observations of all species showed no obvious adverse signs on behavior. Transmitters appeared to be incorporated into preening and often were not visible after attachment except for the antenna. Transmitters were applied during the breeding season and no adverse signs to nesting or reproduction were observed. Application time was less than 5 min with 2 people. Sample transmitters showing design of harness attachment to the transmitter and harness materials will be presented.