Birds make their living in a number of ways.
There are even a few bird species that specialize on other birds. The Peregrine Falcon is one such species. It hunts by swooping down on other bird species, ranging from warblers to gulls. Although birds are a profitable food source, Peregrine Falcon's high position in the food chain has resulted in the accumulation of high levels of the pesticide DDT in Peregrine body tissues. This chemical caused eggshell thinning, pushing the Peregrine falcon to the brink of extinction.