2002-2003 Science Planning Summary

Biology & Medicine

Dr. Polly Penhale
Program Manager


NSF/OPP 01-25608
Station: McMurdo Station
RPSC POC: Howie Tobin
Research Site(s): Beaufort Islands, Cape Bird, Cape Royds, Cape Crozier, Ross Island

Geographic structure of Adelie penguin populations: Demography of population expansion
Dr. David G. Ainley
H.T. Harvey & Associates
Dr. Grant Ballard
Point Reyes Bird Observatory

Deploying Team Members: David G Ainley . Grant Ballard . Michael L Beigel . Katie M Dugger . Carina Gjerdrum . Michelle M Hester . Hannahrose M Nevins . Benjamin L Saenz
Research Objectives: This group investigates the mechanisms responsible for the geographic structuring, the founding of new colonies, and the recent population expansion of the Adélie penguins of Ross and Beaufort Islands. Similar expansion has been occurring throughout the Ross Sea, where 30 percent of the world population of this species resides, and is in some way related to ameliorating climate. So far they have been examining:

The relative importance of resources that constrain colony growth (the amount of nesting habitat versus access to food)

Aspects of natural history that might be affected by exploitative or interference competition among neighboring colonies (breeding success and foraging effort)

Climatic factors that influence the latter, especially extent and concentration of sea ice

Behavioral mechanisms that influence colony growth as a function of initial size and location, emigration, and immigration.

None of the colonies are limited by nesting space, and the researchers have shown how sea ice extent and concentration affect diet, foraging effort, and winter survival. In addition, large colonies affect the foraging patterns of smaller ones within range and, perhaps, ultimately their size. The rate and direction of emigration also appear to be constrained by sea ice conditions, with reasonable concentrations of ice favoring growth of smaller colonies where foraging competition is minimal. Yet to be determined is the demographic mechanism of colony growth (or decline). Reproductive success does not appear to be important, however.

Using seven cohorts of marked penguins from each colony, researchers will assess juvenile survival, recruitment age, and age-specific fecundity and subsequent survival. These data will be compared with another demographic study, the only one for this species, conducted at Cape Crozier during the 1960s and 1970s when populations were declining.

Information will be related to sea ice as quantified by satellite images. Global climate is changing fastest in the polar regions. The Adélie penguin is tied to sea ice, a primary factor in rapid polar climate change (less sea ice, less reflection of solar energy). The extreme sensitivity of these penguins to climate change has been often noted. Understanding the demographic mechanisms behind this sensitivity will contribute greatly to knowledge of the effects of climate change on antarctic marine organisms.

Field Season Overview:
Project team members will travel by helicopter to Cape Royds and Cape Crozier where they will set up their field camp. The work at Cape Bird will be conducted by biologists from LandCare Research New Zealand. Team members will travel by helicopter to two radio telemetry sites on Mount Bird. Both sites will be visited simultaneously, and there will be several visits over the course of a month. Penguins will be observed from these sites using remote radio telemetry to monitor their behavior.

The principal investigator and one or two other team members will travel by icebreaker and helicopter or zodiac to Beaufort Island where they will attach transmitters to penguins and leave a data logger, which they will recover about a month later. If conditions permit, the research team will study the impact of large grounded icebergs on penguin foraging behavior along the north shore of Ross Island. Chilled blood samples will be returned to the home institution for further study.