Several recent studies have confirmed that a number of penguin species at Antarctica, especially chinstrap and Adelie penguin are declining, and the main reason for this is not enough food, which is yet again connected to climate change.
The penguin's diet mostly consists of Antarctic krill, a little shrimp-like animal. Krills belong to the most abundant species on our planet (there can be sometimes up to 30,000 krills in a cubic-meter of seawater) but their abundance has started to severely reduce for penguins because of not only warmer waters but also because of the increased competition from whales and seals who also have krills on their menu.
Krills play extremely important role in Antarctica's ecosystems, and their abundance is the key in preserving the unique Antarctica's biodiversity.
The before mentioned chinstrap and Adelie penguin have been experiencing a decline in population by up to 50% since the mid 80s.
The main difference between these two penguin species is the fact that Adelie penguins love ice while chinstrap penguin avoid ice. Since both of these penguin population experienced severe decline in last 20-30 years the scientists concluded that the loss of ice cover is not the main reason behind their decline but rather the lack of krill.
This was clearly confirmed by comparing the numbers of these two penguin species in the 19th to mid-20th Centuries (when penguin population was the highest because humans almost extirpated seals, baleen whales and some fish which meant more krill for penguins) and today.
The abundance of krill for penguins is not only reduced because of many competitors but also because of climate change. Warmer waters and less ice cover is altering the adequate physical conditions necessary to sustain large krill populations.
If warming continues there will be less krill, and with it the less penguins in Antarctica.