How are scientists able to say that a random species is extinct? Did they have to look everywhere?

Question

How are scientists able to say that a random species is extinct? Did they have to look everywhere?

In: 14

Answer 1

For large endangered animals that have been carefully tracked for a long time, it’s easier to declare them extinct with strong confidence (species of rhino, for instance).

For smaller, more cryptic species it’s really just a matter of not being able to find any after several years of looking. But of course there’s some chance that it’s not actually extinct.