die off
To become extinct gradually, as of a group of people or animals. That species of birds will die off if we keep destroying their habitat.
die off
[for a living thing] to perish one by one until there are no more. Most of the larger lizards died off eons ago. It would be really bad if all the owls died off. The cucumber blossoms all died off.
die off
Perish one by one, as in A celibate community, the Shakers are dying off. [Late 1600s]
die off
v. To become extinct gradually: The dodo died off in the 1600s. Wolves were dying off in the formerly rural area as new subdivisions were built.