List of Species of less than 1000 remaining

PNAS has a list of vertebrates (excluding fishes) of which fewer than 1000 individuals remain.

Since these are scattered across the world, and many are narrow endemics, I would predict that you have not seen many of them in the wild unless you are very well-traveled and/or live in a biodiversity hotspot. I can say that I have encountered one of these in the wild: the Hawaiian goose. Once in its most typical habitat, the lava fields of Kilauea, and the other time in a reintroduction area, among the lush greenery of Hanalei.

Anyone else have stories of encountering one of these species?


I stopped counting how many from the list I’ve seen in the wild once I realized how incomplete and in error the list is, based on my experience working on the conservation of some of these species.

Just within the primates here are some that are missing or in error (and if there are this many missing from the primates then it’s absolutely certain that a lot are missing elsewhere in the list too):

Trachypithecus poliocephalus White‐headed Langur this is the Cat Ba Langur, not the White-headed Langur (see below)

  • Note: this is one of the species with a vanishingly small population that I’m responsible for the conservation of - present population 71, up from a low of 40 or less.

Trachypithecus leucocephalus - White‐headed Langur CR
Trachypithecus delacouri - Delacour’s Langur CR
Rhinopithecus avunculus - Tonkin snub-nosed monkey CR
Presbytis chrysomelas - Sarawak surili CR
Propithecus candidus - Silky sifaka CR
Leontopithecus caissara - Superagüi lion tamarin CR
Cebus flavius - Blond capuchin EN
Prolemur simus - Greater bamboo lemur CR
Semnopithecus ajax - Kashmir gray langur EN
Callicebus coimbrai - Coimbra Filho’s titi EN (likely below 1000, more survey work needs to be done)
Pygathrix cinerea - Gray-shanked Douc langur CR
Macaca munzala - Arunachal macaque EN
Rhinopithecus brelichi - Gray snub-nosed monkey EN
Brachyteles hypoxanthus - Northern muriqui CR
Pongo tapanuliensis - Tapanuli orangutan CR

That’s 15 missing species and 1 error that I caught just in primates alone.

And there are a few more where the population is dropping and is likely to already be below 1000, as well as a number of lemurs where genetic work is leading to the designations of new species that have very small populations.


Hawaiian Goose (Nene) is one I’ve seen but only after a few trips to Hawaii. It remained elusive for me for several years.

Black-footed Ferret is another I’ve seen in the wild at a reintroduction site, both as newly-released and recaptured captive-reared individuals, and also as wild-born individuals. Seeing one of those rare mammals in a wild setting during surveys, illuminated in your spotlight at 3:00 in the morning, just doesn’t get old.

Thanks for this. I could not find some species I thought I was aware of and needed more context. The list you provided was an appendix to this article:

Just wondering because I was surprised to see somethings missing. Is it possible that collections of species in zoos, breeding programs, and private collection, could skew remaining individuals to beyond 1000?

I’ve seen and fed Nenes and Laysan Ducks… at the aviary I volunteered for in Washington state. Wild…

I have seen evidence of Black-footed Ferrets; scat, tracks, etc, but that was well over 10 years ago before I knew about iNat and was taking photos.

That’s possible, but in the majority of the cases I listed there are either no animals in captivity, or the number in captivity is so small as to make no difference at all to the total species count.

Regardless, population counts like this are generally done for the wild portion of the species.

I’d be willing to bet that this list is also badly off for amphibians and the reptile portion of it looks suspiciously small as well. The bird portion also seems small to me.

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This is what had me wondering because I have one bird from New Zealand that is far less than 500 and one from Indonesia that is in the same position - both not on the list.

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