A Pennsylvania-based birder observed a warbler bird in his backyard, and it was immediately clear that the bird is like no other. In fact, DNA sequencing showed that this warbler bird is a hybrid of three species in one, which stunned scientists.
Natural hybrid birds are of extreme importance when it comes to conservation. Such animals which mate with other species can lead to sterile offspring or birds which are so diverse that no other birds would want to mate with them.
“It tells us that warblers in general appear to be reproductively compatible over millions of years of independent evolution,” Cornell Lab of Ornithology postdoctoral associate Dave Toews told Gizmodo. “The things that really define them, their distinct colours and their songs, are likely mating barriers, and that they don’t interbreed because they can’t, but because they choose not to.”
Birder Lowell Burket knew something was wrong with the bird that landed in his yard this past May. He immediately knew it was a hybrid because it looked like a Brewster’s warbler, which is a hybrid of the golden-winged and blue-winged warbler. However, the beautiful bird sang like a third species of bird — the chestnut-sided warbler. It also had the chestnut-sided warbler’s signature red patch on its side. After watching the bird he believed to be three species in one, he emailed Cornell researchers.
“I tried to make the email sound somewhat intellectual so they wouldn’t think I was a crackpot,” Burket told the Cornell Lab of Ornithology. “Having the photos and video helped.”
At first Toews was skeptical because there have been a lot of false alarms on mixed bird species. However, he had been looking for a hybrid between the Vermivoragenus, which includes blue-winged and golden-winged warblers, and their hybrids, and the Setophaga genus, which is the chestnut-sided warbler. Male chestnut-sided warblers often fight with the Vermivora warblers over territory. However, it had been unclear how they interacted with females, according to a paper published in Biology Letters.
Toews and Burket successfully caught the bird in a net and took a blood sample before setting it free. Toews analyzed the bird’s mitochondrial DNA and found that it was indeed three species in one. They presumed the hybrid bird to be the result of a hybrid golden-winged warbler and blue-winged warbler that mated with a chestnut-sided warbler.
Since mitochondrial DNA only gives information about maternal lineage, the analysis wouldn’t reveal if the bird’s mother was a hybrid or not. After further testing, scientists found that the mother was a hybrid. That made her offspring three species in one and two genera in a single bird, which makes this the first record of an inter-species hybrid mating with a bird from a different genus, according to the paper.
Scientists still don’t know whether the three-in-one bird managed to reproduce with another bird or if it could mate at all. However, according to Gizmodo, it returned to Burket’s patch while flying south this fall.