Locator map for our study area at Beaufort Island, Ross Sea, Antarctica.

<p>Left, the location of the Ross Sea region; middle, the location of Beaufort Island and the locations of other Adélie penguin colonies on nearby Ross Island (A. Cape Bird, B. Cape Crozier, C. Cape Royds) and, right, the location of the main Adélie penguin colony on Beaufort Island.</p

Average summer (November–February) temperatures in °C recorded at McMurdo Station, approximately 90 km south of Beaufort Island, Antarctica, during 1958–2010.

<p>Average summer (November–February) temperatures in °C recorded at McMurdo Station, approximately 90 km south of Beaufort Island, Antarctica, during 1958–2010.</p

Available habitat (m²) and breeding pairs of Adélie penguins at the main Beaufort Island colony during 1958–2010.

<p>Available habitat was defined as the maximum extent of the guano stain of the colony minus the snow cover (i.e., unsuitable habitat) within the colony boundary.</p

Changes in snow and ice cover and spatial extent of the Adélie penguin colony at the southern end of Beaufort Island, Antarctica, from 1958–2010 using air photos and high-resolution (0.6 m) satellite imagery (copyright DigitalGlobe, Inc).

<p>During the early years, best seen in the 1958 and 1993 image, snow covered the area, with penguins nesting on bare mounds and ridges.</p

Total available habitat (m²), number of breeding pairs (BP) counted from independent air photos, and calculated density (breeding pairs/m²) of the Adélie penguin colony at Beaufort Island, Antarctica, during November/December each year.

<p>Total available habitat (m²), number of breeding pairs (BP) counted from independent air photos, and calculated density (breeding pairs/m²) of the Adélie penguin colony at Beaufort Island, Antarctica, during November/December each year.</p

Satellite images of each Adélie penguin colony within the 4-colony metapopulation in the southern Ross Sea showing colony area at each location.

<p>Clockwise from top left: Beaufort, which has been habitat-limited by steep moraines to the east, a glacier to the north, and the ocean to the west and south; Bird, with a glacier to the east; Royds, with fast ice to the southeast; and Crozier colonies, both east and west, that are separated by a glacial field. Images are QuickBird-2, courtesy DigitalGlobe, Inc.</p