From The Times:
Many colonies have fallen in size by 50 per cent as the penguins have been squeezed by the effects of climate change and overfishing, the WWF said in its report, Antarctic Penguins and Climate Change.
…
Sea ice on the western peninsula of Antarctic has retreated 40 per cent in the last three decades and is thought to be partly to blame for huge falls in the stocks of krill, a shrimp-like creature eaten by the penguins. Another factor is overfishing by humans.
The quantities of krill, which live under the ice where they feed on microscopic plant life, are estimated to have fallen 80 per cent in the last decade alone in part of the conbtinent’s western peninsula.
Warming in the Antarctic western peninsula is taking place about five times faster than other parts of the planet.
Nesting sites are destroyed by the the melting ice and the emperor penguins have suffered more thyan any other species in Antarctica.
Gentoos and chinstraps are being forced further south by the warming temperatures and this is putting extra pressure on the emperors and Adelie species.