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-m2 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.

A study of individually marked smooth snakes Coronella austriaca was carried out in Wareham Forest, southern England between 1992 and 2001. On average, approximately one-third of potential breeding females reproduced each year and within this group, the proportion breeding was positively correlated with snout–vent length (SVL). Successful breeders had a higher than average body condition at the start of the breeding year compared with unsuccessful breeders. The density of gravid females was positively correlated with prey density in the breeding year but not in the year preceding it. No significant relationships were found between the density of non-breeding females and prey density in either the breeding year or the preceding year. Although most breeding females did not produce young in consecutive years, a small proportion did. There was a weak positive relationship between clutch size and female SVL. This study suggests that the potential for female smooth snakes to breed is provided by stored energy reserves but that this potential is regulated by prey availability in the breeding year.