Effects of transmitters on the reproductive success of Tufted Puffins

ABSTRACT.   Although radiotelemetry is useful for monitoring nest attendance and the foraging ranges and distribution of breeding birds, attachment of transmitters may affect reproductive behavior. In 2003, we captured 25 adult Tufted Puffins ( Fratercula cirrhata ) at two colonies in Chiniak Bay, Kodiak Island, Alaska, and fitted them with subcutaneously anchored radiotransmitters (<1.2% of body mass). We determined the presence of radio-marked birds at each study site using automated, remote radiotelemetry systems, and compared rates of nestling growth, fledging mass, and fledging success for chicks with and without (control group) a radio-marked parent. Although most radio-marked adults continued to attend nests after capture and attachment of transmitters, nestlings with a radio-marked parent had lower mean growth rates (6.9 g/d vs. 14.4 g/d) and fledging success (33% vs. 84%) than control chicks. These results suggest that colony attendance by adult puffins fitted with transmitters declined sharply or completely and this led to high nestling mortality. Given the negative effects of transmitters on Tufted Puffins in our study and in other studies of alcids, we suggest delaying the attachment of transmitters until well after the brooding period. In addition, we recommend pilot studies be undertaken to distinguish the possible effects of capture and handling from those of actually carrying the device.