Preliminary investigation into deducing breeding success of African Penguins Spheniscus demersus from automated transponder reader data to reduce disturbance

Abstract

The Endangered African Penguin Spheniscus demersus is in serious decline, with the total population falling at a rate of ∼5% per annum. The need to carry out regular monitoring to collect demographic and phenological data to assist in the planning and implementation of conservation actions needs to be balanced against the disturbance that may be caused by such monitoring. Many African Penguins are now fitted with passive integrated transponder (PIT) tags that can be read remotely by ground readers at fixed locations in the colonies. In this study, we used data from these ground readers, combined with data collected during routine nest monitoring, to demonstrate that it should be possible to use data from the ground readers alone to monitor breeding success in the future. We found patterns of movements that varied during the various breeding stages. Adults took shifts of several days during incubation; during the brood period the adults alternated each day, with one remaining at the nest while the other went to sea. As the chicks grew large enough to be left alone, both parents usually foraged every day until the chicks fledged. In unsuccessful nests adults stopped attending the nest shortly after it had failed. If this work is taken forward it should be possible to greatly reduce the potential impact of regular nest monitoring.