Telemetric Observations of a Robin (Turdus migratorius)

Abstract

Telemetric observations of a Robin (Turdus migratorius).--Radiotelemetry has proved to be a valuable tool in a variety of biological research projects (Slater, Bio-telemetry, New York, Macmillan, 1963).Southern (Wilson Bull., 76: 129, 1964) used radios to track Bald Eagles (Haliaeetus leucocephalus), but the use of transmitters on small birds presents special problems in transmitter design.Because many species of birds are small (under 100 g), and because of the great potential of telemetry in ornithological studies, William W. Cochran of the Illinois Natural History Survey designed a lightweight transmitter (2 to 5 g) for use on small birds.The transmitter is essentially the same as that described by Cochran, Mech, and Bellrose (Univ.Minnesota Tech.Rept., 8, undated) but incorporates the smallest readily available electronic components, and a one-meter fifth banjo string for an antenna.This paper presents some results from the initial field tests of the transmitter.Our receiver was a 28-mc Model D-11 (Cochran and Nelson, Univ.Minnesota Tech.Rept., 2, 1963).We tested low-weight transmitters and imitations thereof on Common Grackles ( Quiscalus quiscula) , a Robin ( Turdus migratorius) , House Sparrows (Passer domesticus), and Starlings (Sturnus vulgaris).One method of attaching the transmitter was to glue it to the back plumage of the bird with Duco cement.Grackles and Starlings would not tolerate transmitters thus attached, and removed their own back plumage to rid themselves of the radio.A House Sparrow, on the other hand, did not attempt to remove a glued transmitter, and carried it very well.A second method was to staple the transmitter to a plastic back tag (for description, see Labisky and Mann, J. Wildl.Mgrnt., 26: 393, 1962) which was then attached to the bird.No passerine bird can remove a back tag and transmitters affixed by this method are certain to stay in place.This is regrettable in one sense, because a low-weight transmitter is short-lived and, unless recaptured, the bird with a back tag is encumbered long after the transmitter dies.The weights of transmitters which various birds can carry without handicap deserve thorough study.We observed that a 30 g House