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. 2011 Apr 11;108(18):7625–7628. doi: 10.1073/pnas.1016560108

Fig. 1.

Fig. 1.

Indices of Adélie and chinstrap population responses. Closed circles (●) indicate chinstrap penguins at Admiralty Bay, King George Island. Open circles (○) indicate chinstrap penguins at Cape Shirreff, Livingston Island. Closed triangles (▲) indicate Adélie penguins at Admiralty Bay. (A) Number of breeding pairs of Adélie and chinstrap penguins at all colonies. (B) Percent change in breeding population size of Adélie and chinstrap penguins at Admiralty Bay. Gray bars highlight the years in which the percent changes in Adélie and chinstrap breeding populations exceed 10% in opposite directions. Annual ice conditions are indicated as SDs from the long-term mean; + or − is between 0 and 1 SD; + + or − − is between 1 and 2 SD; and + + + or − − − is between 2 and 3 SD. No ice data are available for the winters of 2008 and 2009. (C) Recruitment of first-time breeders into the Adélie population at Admiralty Bay. (D) Index of recruitment to the natal colony for Adélie and chinstrap penguins (7). Chinstrap recruitment before 1984 at Admiralty Bay is excluded because of inconsistent resighting effort.