Animal, bird, fish, plant
, or other living organism threatened with extinction by natural or man-made changes
in its environment
. Extinction may occur when a specie's total number falls below the number required
for successful breeding, because its members cannot locate mating partners or their genetic pool
loses the needed variety. According to the International Union
Of Nature, the categories of the risk
of extinction are (1) Endangered: unlike to survive if the causal
factors continue to operate
. (2) Vulnerable: will soon be endangered if the causal factors continue to operate.
(3) Rare: not endangered or vulnerable but at risk.