From The Collaborative International Dictionary of English v.0.48 [gcide]:
endangered species en*dan"gered spe"cies, 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.
Note: 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]