No one, including federal and state agencies or private citizens, is exempt from punishment, and heavy fines and jail sentences can be given for violating the laws. Major responsibilities of the FWS include programs to protect the remaining members of the species and to develop a recovery program designed to return the species to a point at which it can function in a natural manner. Programs for raising some species in captivity have been carried out in attempts to restore former population levels. Examples The list of plant and animal species recognized as endangered or threatened is too long for discussion of each. Selected examples, however, serve to indicate the problems faced and solutions being applied.
Birds provide several modern examples of how extinction can occur.
One of the best known is the passenger pigeon, a species said to have occurred in greater numbers than any other bird or mammal for which there are records. Passenger pigeons looked very similar to mourning doves, a close relative that is still common. The birds, concentrated at nesting sites, were slaughtered for food by the millions. The extinction of the passenger pigeon is a commentary on the erroneous belief that if a species occurs in large numbers it is not necessary to be concerned about its welfare. Although John James Audubon reported seeing more than 1 billion of these birds in Kentucky in 1813, the last member of the species died in 1914.