In the past 300 years, more than 130 species of animals have become _ . One of these extinct species is the passenger pigeon . At one time there were millions of these birds in North America, but now there are none. The last one died in the Cincinnati Zoo in 1914. Another extinct animal is the cape lion . The animal has been extinct since 1860. What cause animals to become extinct? Too much hunting is one cause; pollution is another. Governments around the world have begun to protect wild animals in danger. In the United States, the US Fish and Wildlife Service is responsible for endangered animals. It has listed nearly 200 species of endangered animals in North America. There were many cape lions in North America  _  .
last century in the twentieth century more than one hundred years ago in 1914