Effect of instrument attachment and other factors on foraging trip duration and nesting success of Adelie Penguins

We compared foraging-trip duration of Adelie Penguins (Pygoscelis adeliae) carrying various combinations of radio-telemetry transmitters, implanted, p assively interrogated transponder (PIT) tags, and time-depth recorders at t wo widely separated colonies of different size on Ross Island, Antarctica, during three austral summers. Trip duration was measured by electronic devi ces rather than human observation. Instrumentation had no significant effec t on foraging trip duration. Most of the variation in foraging trip duratio n was attributed to individual and year. Males' trips were significantly sh orter than females' in a subset of known-sex birds. No effect was evident i n nesting success even for birds that wore instruments for >20 days. We rec ommend use of small, hydrodynamically designed and placed instruments to re searchers who wish to collect data unaffected by instrument attachment.