Penguins are endangered because of large-scale fishing operations that diminish their food supply, poachers who steal their eggs and kill adults for their oil, and oil spills that pollute their environment and kill thousands of penguins at once. Penguin populations are also threatened by climate change as the sea ice melts, removing their feeding areas and breeding grounds.
Climate change is the biggest threat to penguin survival and the hardest to counter; penguins are protected from harm under the Endangered Species Act of 1973 and are rescued by environmental groups during oil spills, but their diminishing habitat and dwindling food supplies make it difficult for them to reproduce or thrive. Even penguins outside of the Antarctic are threatened by climate change. The African penguin feasts on sardines and anchovies that follow currents off of small islands, but climate change is causing the streams to move further away from the penguins' homes and out of their territories.
Penguins are also threatened by commercial fishing expeditions. While some fishermen participate in conservation efforts and nurse any injured animals back to life, penguins still have to compete with humans for food. Penguins also face threats from their natural predators: sharks, killer whales, sea lions and leopard seals.