December 9, 2016 // 03:50 PM EST
But it turns out the birds that were once believed to all belong to the same species—the red-bellied pitta—are actually 13 distinct species, found around Southeast Asia.
Image: BirdLife International
This is particularly significant because when they were all lumped together, conservationists weren’t worried about their population numbers. But now that the differences have been teased apart, it’s become apparent that three of these species are actually globally threatened. One species is also considered near threatened, according to BirdLife International, a bird conservation organization, which is the Red List authority for birds for the International Union for Conservation of Nature.
“The birds do look alike but there are significant differences between individual taxa,” explained Nigel Collar, a Leventis Fellow in conservation biology with BirdLife International, who helped to identify the different species.
The first clue came from a team of geneticists who, in 2013, published a paper that showed the red-bellied pitta could be as many as 17 distinct species, based on their genetic diversity. (One factor that can help determine that two animals are separate species is if they are unable to successfully interbreed.) Collar explained that there’s a bit of debate over how genetics is used to determine whether a species is distinct, but the evidence convinced him and his colleagues to take a second look at the pitta.
“We sat down in British Museum and got out all the specimen and evaluated these slightly different or fairly different subspecies,” Collar said. “So you’re comparing the differences: maybe one has a big bill and another has a small bill; a large wing or a short wing.”