News > How many birds are there in the world?

How many birds are there in the world?

Counting all the world’s birds would be much trickier, for obvious reasons, but years later Callaghan nevertheless set out to be the first to come up with a hard number—or at least a plausible range.

In a new paper, he and two other researchers at the University of New South Wales in Sydney, Australia, estimate there are likely between 50 billion and 428 billion birds on Earth.