This unique warbler is 3 bird species in 1

November 13, 2018, 12:14 p.m.
A hybrid warbler in Pennsylvania.
Photo: Lowell Burket

Bird-watching pays off in a number of ways, from getting you outside to learning something new and keeping your eyes keen. It also can lead to the discovery of a unique species.

Lowell Burket is a dedicated birder in Pennsylvania. He noted an odd bird back in May 2018, one that sang like a chestnut-sided warbler with the characteristics of both blue-winged and golden-winged warblers. Burket saw the bird a number of times, and he eventually reached out to the Cornell Lab of Ornithology's Fuller Evolutionary Biology Program to see what they thought about this potentially weird feathered friend.

"I tried to make the email sound somewhat intellectual so they wouldn't think I was a crackpot," Burket said in a Cornell University-issued press release. "Having the photos and video helped. Within a week researcher David Toews came down. We found the bird again and collected a blood sample and measurements. It was a very interesting and exciting morning for us. A few days later I got a text message from Dave saying, 'You were right!!!'"

The blood tests made all the difference, revealing the genetic history of Burket's warbler find.

A front view of a hybrid warbler This hybrid warbler has a complicated family tree. (Photo: Lowell Burket)

The family tree likely breaks down like this: Blue-winged and golden-winged warblers have been creating hybrids for a number of years now, resulting in what's known as a Brewster's warbler. A female Brewster's warbler likely mated with a male chestnut-sided warbler and hatched the warbler Burket observed. The Brewster warbler and the chestnut-sided warbler are each from a different genus, making the three-in-one hybrid particularly rare.

It also may indicate bad news for warblers overall. Brewster's warblers are the result of golden-wing warblers suffering from population declines, and thus they mate outside their species with the blue-winged warbler. This new warbler may be sterile, or other birds may be confused by what it is and not want to mate with it. This may exacerbate population decline since there's no way for genetic material to be passed on to another generation. As a result, scientists are going to keep an eye on this rare warbler to see what happens. They published their initial findings in the journal Biology Letters.

For his part, Burket thinks the find confirms the joys of birding.

"I had literally zero knowledge about birds until seven years ago," he said. "And now I end up discovering what appears to be a first-of-its-kind bird. It can happen to anybody!"

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