The Prydz Bay Adelie Penguin/Prey Stock Interaction, a Monitoring Program

Brief description

Metadata record for data from ASAC Project 106
See the link below for public details on this project.

From the abstracts of some of the referenced papers:

This paper reports the results of the first aerial photographic survey of Adelie penguin colonies in the Prydz Bay region. The area surveyed extended from the northern Vestfold Hills to the Publications Ice Shelf. More than 325,000 pairs of Adelie penguins were estimated to be breeding in this region in 1981/82. The great majority of breeding Adelie penguins occurred in the northern half of the region surveyed, in the Vestfold hills and Rauer Islands, where most colonies were located. This is probably due to the typical pattern of summer sea-ice dispersal, which usually results in sea-ice leaving the northern areas of the coast first.

Prydz Bay supports nine seabird species that breed on the Princess Elizabeth Land coast: two penguins, six Procellariiformes and one skua. Information on their diet is reviewed. Apart from the scavenging South Polar Skua Catharacta maccormicki and Southern Giant Petrel Macronectes giganteus, three diet types were distinguished. First, the Emperor Penguin Aptenodytes forsteri ate almost exclusively fish; secondly the Adelie Penguin Pygoscelis adeliae, Cape Petrel Daption capense, and Wilson's Storm Petrel Oceanites oceanicus consumed at least 60% euphausiid, the remainder largely fish; and thirdly, a diet of greater than 60% fish, the rest euphausiids, was taken by the Southern Fulmar Fulmarus glacialoides, Antarctic Petrel Thalassoica antarctica and Snow Petrel Pagodroma nivea. Seasonal fluctuation in composition of Adelie Penguin, Cape Petrel and Southern Fulmar diet suggested either fluctuating foraging ranges or movement of Euphausia superba inshore during summer months. Annual fluctuation in diet composition was correlated with seabird reproductive success. When E. crystallorophias dominated the euphausiid component of Adelie Penguin diet, reproductive success was high; when E. superba was scarce in Prydz Bay, Antarctic Petrel and Southern Fulmar productivity was low.

Breeding phenology, success and nest attendance of Antarctic Petrels Thalassoica antarctica and Southern Fulmars Fulmarus glacialoides at the Rauer Group, East Antarctica, are discussed. Most data were collected on Hop Island in January and February 1988, and from December 1988 to March 1989. Observations extended from the late stages of incubation to post-guard or fledging periods. Some annual breeding indices collected from 1983 onwards at census sites are compared with meteorological data and the extent of fast ice for the nearby Davis Station. Both species had a restricted hatching period, reflecting a brief and synchronised egg-laying period, reflecting a brief and synchronised egg-laying period, typical of other southern fulmarine petrels. Antarctic Petrel chicks hatched from 4 January (1989) and c. 90% appeared by 16 January (both years). Southern Fulmar hatching began on 21 January (1988) and almost all chicks appeared by 6 February (both years). Adult attendance at nests declined with increasing chick age. For Antarctic Petrels, this was most marked at about 11 days; no chicks had continuously attendant adults after 24 days, although adults returned to feed them. Incubation shifts following hatching and the post-guard period started, on average, 13 days after hatching. Egg and chick losses varied between years and sites. The South Polar Skua Catharacta maccormicki was apparently involved in the majority of losses. Nest sites of both species resemble those elsewhere: Southern Fulmars may require steeper sites, allowing a fall away from colonies. Antarctic Petrels are less affected by accumulation of snow or ice and shelter from katabatic winds may be important. Although weather may modify breeding success locally, annual success must depend on the ability of parents to produce eggs and feed chicks: this may be moderated by the extent and persistence of pack ice.

Annual chick productivity and breeding success, recorded at four Adelie penguin, Pygoscelis adeliae, colonies at Magnetic Island in eastern Prydz Bay, are presented for the seven breeding seasons 1981/82 to 1987/88. The adult breeding population remained relatively stable during the first 4 years of the study, and increased in hte last 2 years. Substantial annual variation in breeding success occurred over the study period, ranging between an estimated 0.69 and 1.33 chicks surviving until late creche stage per nest for seasons 1985/86 and 1982/83 respectively. Annual patterns of chick productivity in southern fulmar, Fulmarus glacialoides, and Antarctic petrel, Thalassoica antarctica, populations within Prydz Bay were synchronous with those of Adelie penguins. In the years of highest and lowest reproductive performance, prey abundance within the likely foraging areas was correspondingly high and low. Reproductive performance was greatest in years when fast-ice breakout occurred before the end of December (1981/82, 1982/83. 1986/87 and 1987/88) and lowest when the breakout was after (1983/84, 1984/85 and 1985/86) and pack-ice cover persisted within the foraging range of the birds during the chick-rearing period.

Lineage

Progress Code: completed

Statement: Dates provided in temporal coverage are approximate only.