n. sing. & pl. A species of plant or animal that has declined in numbers to a point where further irreversible decline and extinction{ 3 } has a significant chance. Lists of endangered species are maintained by government agencies, and in many cases the killing of such species or destruction of their habitat is prohibited by law. In the U. S. in recent years, development of certain tracts of land has been prohibited due to the likelihood that it will cause a reduction in the numbers of an endangered species. In some cases environmental organizations have initiated litigation to cause the courts to rule that a certain development plan is illegal due to a threat to an endangered species. Laws protecting endangered species have become in some cases a contentious political issue. [ PJC ]