An interesting new paper has just been published in Nature Scientific Reports: A reversal of fortunes: climate change ‘winners’ and ‘losers’ in Antarctic Peninsula penguins. Scientific Reports. 4: 5024. DOI: 10.1038/srep05024 Gemma Clucas and co-workers used molecular techniques to examine historic population sizes of three Antarctic Peninsula penguin species: Adelie Pygoscelis adeliae, chinstrap P. antarctic and gentoo P.papua. As all three specis require bare ground to nest, and adjacent open water to forage effectively, the extent of ice cover limits their distribution. As climate warmed after the Last Glacial Maximum (LGM, ca 19.5–16 kya) habitat increased for all three species with declining ice extent and they expanded their populations southwards.
Historic penguin population estimates
The continued recent warming (in the last 50 years) has not had the same effect. Gentoo penguins, which are generalist feeders, have continued to expand southwards as more breeding areas have become available. In contrast Adelie and Chinstrap penguins, which feeds almost exclusively on krill, have been declining (see this paper by Carlini et al for a comparison of Gentoo and Adelie populations). Current thinking is that the recent reduction in sea ice is causing a decline in krill, although snow build up and increased melt-water have also been implicated in the recent declines.
Adelie penguins in the Antarctic Peninsula have expanded southwards since the LGM. Those in East Antarctica are limited by available nesting sites, and are probably as far south as they can go.
The full report can be found on the Scientific Reports page here.
The Bowerbirder 