Asked by: Matthew Cox, Wantage
It’s quite hard for a predator to drive itself extinct simply by being such a good hunter that it eats all of the available prey. Normally, evolution is a very slow process and predators are engaged in an ongoing arms race with their prey, who are also evolving new ways to escape.
If the balance starts to shift in favour of the predator, the amount of available food dwindles and the predators aren’t able to raise as many young. This allows the prey population to recover and equilibrium is restored.
But when a predator specialises to hunt a single prey species, it can get trapped in an evolutionary dead end. This happened to the Haast’s eagle in New Zealand, which had evolved to prey exclusively on the flightless moa bird. When humans arrived in the 13th Century, the moa were hunted to extinction within 200 years. The Haast’s eagle couldn’t adapt to find new prey and went extinct too.
This phenomenon, known as ‘coextinction’, is also common with parasites that have adapted to live on a single host animal.
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