Status of white-chinned petrels Procellaria aequinoctialis Linnaeus 1758, at Bird Island, South Georgia

• Published in: Antarctic Science
• Main Authors: Berrow, Simon D., Croxall, John P., Grant, Sharon D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2000
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Antarctic; Bird Island; Burrows; Antarc*; Antarctic Science; Arctocephalus gazella
• Online Access: http://dx.doi.org/10.1017/s0954102000000468; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102000000468

The white-chinned petrel ( Procellaria aequinoctialis ) is an abundant, widespread petrel breeding in tussock grassland at sub-Antarctic islands. Over the last decade it has been killed in large numbers in temperate and sub-tropical longline fisheries. However no data are available on the global population status. We assessed the status of white-chinned petrels at Bird Island, South Georgia by comparing the distribution and density of occupied burrows in 1981 and 1998. In both surveys white-chinned petrel burrows occurred in one-quarter of the 460–477 36-m 2 quadrats surveyed. The total number of burrows in each quadrat was consistent between each survey but we estimate an overall decrease of 28% in those occupied (with considerable variation between sites). Concurrent data on breeding frequency and success showed that white-chinned petrels are essentially annual breeders at Bird Island; breeding success was consistent at around 44%. Significant factors determining densities of occupied burrows were crown height and percent tussock cover (accounting for 77% of variance). The former has decreased significantly, the latter increased significantly between 1981 and 1998 but there was no relationship between white-chinned petrel occupancy rate and habitat modification due to the presence of fur seals ( Arctocephalus gazella ). This suggests that any population decline is due to factors operating away from the breeding colony, such as those attributed to fishing.