As many as 10 of the 17 kinds of penguins may be in danger of disappearing. The number of penguins have decreased by 30% since 1987. Penguins are black and white birds that live in the southern part of the world. They are common in South America , New Zealand , Australia and South Africa. Many live near cold waters. But some live near warm waters in Galapagos Islands. Penguins cannot fly , but they are fine swimmers. Penguins eat fish and krill( 磷虾 ). The warming of the earth is the decrease in penguin populations. The heating of the air has caused ocean waters to become warmer. Higher water temperatures have reduced the supply of fish and krill. Some years later these birds are completely unable to reproduce( 繁殖 ). Besides , many adult penguins die of hunger. Widespread( 广泛的 ) fishing , exploration for oil and oil leaks( 漏 ) also make penguins be in danger. Poisonous organisms( 生物 ) in ocean water are another danger. Penguins also have their enemies , including wild dogs , sharks , seals and sea lions. News about penguins is not all bad , however. Several years ago , oil leaking from a ship hurt 40% of the penguins in South Africa. The penguins became covered with oil. But thousands of people helped clean and treat the birds well. Then they returned the penguins to the wild. Now these South African penguins are reproducing in higher numbers than before the oil leaking.