When a species is whittled down to just a few, the world watches anxiously as the last member perishes. Such was the case with Sudan, the last male northern white rhino that died earlier this summer.

However, a new study published today in the journal Biological Conservation found that eight rare bird species may have already quietly disappeared.

Funded by the non-profit BirdLife International, the eight-year study statisticaly analyzed 51 critically endangered bird species and found that eight could likely be classified as extinct or very close to extinction: They found that three are extinct, one is extinct in the wild, and four are precipitately close to extinction if not already gone.

One species, the Spix's Macaw, was featured in the