Counting down
What Does Endangered Mean?
An animal can be in serious trouble while there are still thousands of them, and safe with only a few hundred.
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Step 1 of 5
The count alone does not decide it.
A species with thousands left but halving every decade is in far more trouble than one that has held steady at a few hundred for centuries.
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Step 2 of 5
Small populations get unlucky.
With very few individuals left, an ordinary bad year — a storm, a disease, a failed breeding season — can take out a large share of what remains all at once.
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Step 3 of 5
Being scattered is its own problem.
A thousand animals in one place is not the same as ten groups of a hundred that never meet. Small isolated groups breed among themselves and lose variety.
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Step 4 of 5
Habitat is usually the real cause.
Most endangered animals are not hunted out. They are squeezed out, as the place they are built for is cleared, drained, built on or cut into pieces.
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Step 5 of 5
It can be reversed.
Species have come back from a few dozen individuals when the cause was removed and the habitat protected. It is slow and it works, and it is far cheaper done early.
Some populations came through a near-miss so narrow that every animal alive today descends from a handful, and the lack of variety still shows.
The short version
Endangered describes a trend and a set of risks, not just a headcount — a shrinking, scattered population is in trouble long before it is small.
Try it yourself
Plot any number that is halving — 800, 400, 200, 100. The drop from 800 looks slow and the end comes quickly.