Breeding ecology of Antarctic petrels and southern fulmars in coastal Antarctica

PhD ceremony: Mr. J.C.S. Creuwels, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Breeding ecology of Antarctic petrels and southern fulmars in coastal Antarctica

Promotor(s): prof. W.J. Wolff

Faculty: Mathematics and Natural Sciences

Petrels are the most numerous bird group in the waters around Antarctica. During three seasons, Jeroen Creuwels studied the ecology of petrels on small and rocky Ardery Island in Antarctica. Antarctic Petrels and Southern Fulmars need more than three months to complete their breeding seasons, whereas favourable conditions are restricted to the short Antarctic summer. Despite a different timing of breeding, both species achieved a similar breeding success. The first breeding species was the Antarctic Petrel, but this species lost many eggs early in the season. Extreme snowfall had other unexpected consequences: giant petrels were able to land in the colony. In the first season 10% of the adult birds were predated and much disturbance was caused which enabled South Polar Skuas to take nearly all eggs. Southern Fulmars are less capable of flying over sea ice and therefore they started breeding more than two weeks later, which resulted in more losses at the end of the chick phase due to early winter conditions.

An automatic weighing system provided data on changes in masses of chicks and parents. Chicks of both species were growing equally fast, although chicks of Antarctic Petrels received much less food. Antarctic Petrels flew to more than 300 km to find food for their chicks and they provisioned their chicks with one meal per day. Southern Fulmars foraged closer to the colony and were able to give their chicks almost twice as much food. Probably Antarctic Petrels were able to process more food in the stomach on the way, which resulted in chick meals with a higher energetic value per gram.

The Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) has designated the Antarctic Petrel as an indicator species for the Antarctic ecosystem. This study shows that local factors can have large effects, which should be taken into account when monitoring of human influences like fishery activities.