CCAMLR

The numbers of Adelie penguins Pygoscelis adeliae (Hombron and Jacquinot) in the Ross Sea, Antarctica, have increased markedly over the past 10 years. Proportionally, this increase is most pronounced in McMurdo Sound, where the species’ breeding range has recently been extended 3 km south to Cape Barne (77°35’S) with the re-occupation of a former rookery that was abandoned sometime before the present century. These biological trends show remarkable synchronisation with physical evidence of climatic variation in the McMurdo Sound region. We suggest that the dynamics of Adelie penguin populations may be very sensitive indicators of changes in the Antarctic climate.

Published in: New Zealand Journal of Ecology Vol. 14 (1990)

The population dynamics of the Cape Royds rookery were modelled by computer, in order to determine the probable causes of the dramatic increase since 1980 in the numbers of Adelie penguins, Pygoscelis adeliae, breeding in the Ross Sea region, Antarctica.
Variations in the extent of sea-ice around the rookery during incubation and chick rearing cannot feasibly explain the population increase and another factor or event must be introduced, which increases chick production per breeding pair and decreases adult mortality. The timing of the event is critical and rules out the cessation of human impacts or the depletion of competing baleen whales as causal factors. The event is seen as most probably the result of a recent warming of the Ross Sea climate.

Published in: New Zealand Journal of Ecology (1991) 15(2): 117-121

A System that automatically weighs, identifies and determines the direction of penguins moving between their breeding colony and the sea is described. Data obtained from it for a complete colony (589 nests from which 412 chicks were fledged) and related to the foraging ecology of the Adélie penguin Pygoscelis adeliae are presented for the period hatching to fledging. These were obtained at Bechervaise Island (total Adélie penguin population 1816 nests) near Mawson Station Antarctica during the 1991/2 breeding season. The System logged more than 80,000 penguin crossings over a period of three months. Results show that from hatching (20 Dec-10 Jan) onward males and females deliver a similar mass of food to the chick per visit despite males being approximately 480g (11.5%) heavier when empty. A mass of forty five kg was delivered to the colony for each chick raised to fledging. The average fledging weight was 3.1kg. The value of the System for large scale data collection in long term monitoring and ecological studies is discussed.

Krill distribution and abundance were estimated from four acoustic surveys, conducted in the vicinity of Elephant Island, Antarctica, from mid-January to mid-March, 1992. The first and last surveys covered a 105 by 105 n.mi. study area centered on Elephant Island; the second and third surveys covered a 60 by 35 n.mi. area immediately north of Elephant Island. During the first survey, krill were distributed in a wide band extending along the north side of Elephant Island and wrapping around the western end; biomass was estimated to be 2. 2 million metric tons. During the second survey, the highest densities of krill were over the shelf extending to the northwest from Elephant Island and including the Seal Island archipelago; high densities of krill also extended off the shelf from the northeast end of Elephant Island into deeper water. Biomass in the smaller survey area was estimated to be 0.7 million metric tons. Three weeks later, high krill densities were still apparent in the vicinity of Seal Island, but the area of high density previously mapped off the northeast end of Elephant Island had retracted considerably; biomass was estimated to be 0.4 million metric tons. During the final survey, conducted six weeks after the first survey, krill were mapped in reduced densities primarily to the west of Elephant Island; biomass over the larger survey area had declined to 1.1 million metric tons.