FORAGING BEHAVIOR AND REPRODUCTIVE SUCCESS IN CHINSTRAP PENGUINS - THE EFFECTS OF TRANSMITTER ATTACHMENT

The effects of radio transmitter attachment on foraging trip duration and reproductive success of breeding Chinstrap Penguins (Pygoscelis an tarctica) were studied on Seal Island, South Shetland Islands, Antarct ica. Attachment of transmitters having a cross-sectional area 0.9% tha t of the penguin had no significant effect on foraging trip duration, nest visit duration or the number of foraging trips per nest per day. Adults equipped with transmitters had significantly lower chick surviv al rates than control animals, however. This difference resulted from a higher nest failure rare of transmitter-equipped adults. Most of the se failures occurred in the early part of the guard period. The averag e number of chicks raised to the creche stage in successful nests was similar for control and transmitter-equipped animals. Thus, chick mort ality occurred as a result of failure of the entire nest (i.e., abando nment by the adults) rather than lowered chick survival in individual nests. Nests at which both members were equipped with transmitters fai led at a higher rate than nests at which one member was equipped with a transmitter. The transmitters used in this study may be considered a maximum size to be used for foraging trip duration experiments of med ium-sized penguins.