Notes on Blue and Kerguelen Petrels Found Beach-washed in Victoria, 1984

Abstract

Weights and measurements from Blue and Kerguelen Petrels Halobaena caerulea and Pterodroma brevirostris found beach-washed in Victoria between 23 June and 8 September 1984 are given, and details of reproductive condition, items found in gizzards and aspects of feather wear and moult are also presented. Some data from birds held in the Western Australian Museum, and the Museum of Victoria, are also discussed. Whilst body measurements of the 1984 birds were similar to those presented by other authors for birds caught on breeding islands, body weights were reduced by about a third.

The gizzards of both species contained cephalopod remains (from eight families), but Blue Petrels had ingested a variety of food items (including freshwater and terrestrial insects), and debris (including plastic pellets, foil and fragments, aluminium foil and pumice), apparently from the sea surface. The probable difference, and consequences, in feeding strategies in relation to diet, bill structure and wing loading are discussed.

From feather wear and reproductive parameters we conclude that the wrecked Kerguelen Petrels were of a mixed age, but the Blue Petrels were mostly birds of the year. Assuming an origin to the west and or south of Australia, weather systems preceding their occurrence are discussed. The strong winds which finally drove them onshore may have been the proximate cause of death but it is likely that such birds were already weakened by starvation and depletion of food resources.