Penguins have a large effect on the Antartic peninsula. Although population has been taking a decline, penguins still dominate the area. Penguins need a lot of space to live and breed. Therefore they take up a lot of the space on the ice. The penguins mainly feed on krill, which are small shrimp like animals. The density of krill has been up and down over the last couple of decades, due to climate change.