Functional extinction

Other Names:
Species extinct in the wild
Non-viable wild population of endangered species
Animals surviving only in zoos

Functional extinction is the extinction of a species or other taxon such that:

It disappears from the fossil record, or historic reports of its existence cease; The reduced population no longer plays a significant role in ecosystem function; or The population is no longer viable. There are no individuals able to reproduce, or the small population of breeding individuals will not be able to sustain itself due to inbreeding depression and genetic drift, which leads to a loss of fitness.

In plant populations, self-incompatibility mechanisms may cause related plant specimens to be incompatible, which may lead to functional extinction if an entire population becomes self-incompatible. This does not occur in larger populations.

In polygynous populations, where only a few males leave offspring, there is a much smaller reproducing population than if all viable males were considered. Furthermore, the successful males act as a genetic bottleneck, leading to more rapid genetic drift or inbreeding problems in small populations.


The last sighting of a Guam kingfisher in the wild was in 1988.  All living Guam kingfishers are descended from just 29 captive individuals taken from the wild in the 1980s to U.S. zoos to create a breeding program to save the species from extinction.

Broader Problems:
Holocene extinction
Problem Type:
G: Very specific problems
Date of last update
15.04.2022 – 10:30 CEST