Giraffe populations have been rapidly decimated across Africa to the point that the species is threatened with extinction, according to a prominent international conservation group.

Giraffes were once listed as a species of "least concern" by the Belgium- and U.K- based International Union for the Conservation of Nature, but poaching, habitat loss, civil unrest and other factors have led to rapid declines in five out of the nine giraffe subspecies in various African regions.

Giraffe numbers have fallen 36 percent to 40 percent — from a range of between 151,000 and 163,000 individuals in 1985 to about 97,562 in 2015, said the group in a news release, which now lists the species as "vulnerable."

Three other giraffe subspecies appear to be on the rise, but not enough to offset overall drops. One subspecies appears to be holding steady.

The IUCN Red List separates species into 7 categories, ranging from "least concern" to "extinct." The category "vulnerable" is given for animals that are threatened, but do not yet meet the group's threshold for endangered status.

The Red List is typically updated at least once a year.

This most recent update includes several bird species at various levels of vulnerability, including many species that have only recently been discovered or described by scientists. The Antioquia wren, discovered along Columbia's Cauca River in 2010, was listed this year as endangered due to the planned Ituango dam construction project that would destroy half of the bird's habitat, according to the IUCN.

Invasive species led to the extinction of 13 species of island birds, according to the group.

One particularly notable bird species newly listed as endangered is the African grey parrot, a popular pet known for its ability to imitate human speech. Trapping and habitat loss have mostly driven the parrot's declines in the wild.

However, a few threatened bird species, such as the Azores bullfinch, are showing signs of recovery due to conservation efforts.