Never-before-seen colorful hybrid bird spotted in Pennsylvania
This hybrid bird is a descendant of the Rose-breasted White Finch and the Scarlet Tanager. PHOTO: STEVE GOSSER TEXT: ANNIE ROTH Recently, bird watcher Stephen Gosser was walking in the woods in Lawrence County, Pennsylvania, when he heard a chirping bird he thought was a scarlet tanager. These colorful songbirds are hard to spot, so Gosser followed the bird's merry call and tried to get a closer look. However, when the bird finally came into view, Gosser couldn't tell if it was a scarlet tanager. It has neither the bright red body of the male tanager nor the bright yellow plumage of the female. The bird has brown wings, a speckled breast, and a tuft of red feathers on the throat, somewhat similar to the rose-breasted white finches. This is a rose-breasted white-breasted finch (Pheucticus ludovicianus). PHOTO: JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK The scarlet tanager (Piranga olivacea) is known for its beautiful singing. PHOTO: JOEL SARTORE, NATIONAL GEOGRAPHIC PHOTO ARK "I'm so confused," Gosser said. He saw the bird in July 2020, and has more than a decade of birding experience, but has never heard "the rose-breasted white finches chirping like a scarlet tanager". To find out the bird's identity, Gosser visited Bob Mullvhill, an ornithologist at the National Aviary in Pittsburgh. With Gosser's help, Mullvhill found the bird, took a small blood sample from the veins in its wings, performed genetic testing, and released it into the wild. The test results, published in the July issue of Ecology and Evolution: Gosser discovered that the mysterious bird was a hybrid offspring of the rose-breasted whitefinch and the scarlet tanager. The emergence of a hybrid of these two highly differentiated species, which had never been seen before, raised many questions: How many hybrids remain to be discovered? This hybrid bird has a call like a scarlet tanager, but looks more like a rose-breasted white-finch. PHOTOGRAPHY: STEVE GOSSER Do they cluster together? Both the scarlet tanager and the rose-breasted white-breasted finches are forest-dwelling songbirds that come to the eastern United States during the breeding season. The last common ancestor of the two birds was 10 million years ago, so they are as different as domestic cats and tigers. It's a bit odd that the two were able to successfully interbreed, considering how closely related they are. However, birds differ from mammals when it comes to hybridization rules. "Birds have been able to hybridize over a long period of time. That's not common in mammals," said David Toews, an assistant professor of biology at Penn State who specializes in bird hybridization. Wild grey geese and Canada geese took different evolutionary paths 12 million years ago, and while they can interbreed, successful interbreeding between such distant relatives is very rare in birds, Toews said. The rose-breasted tanager and the scarlet tanager are quite different in shape and behavior. However, their ability to interbreed suggests that the two species, despite long-term divergence, remain genetically similar. Perfect Fusion Toews and colleagues sequenced the hybrid bird's genes and found that its mother was a rose-breasted white-breasted finches and its father was a scarlet tanager. It's a 1-year-old male and has acquired healthy genes from both parents -- the mother gave it a rosy chest and a white belly, and the father gave it a slender beak. The bird looked like a perfect blend of its parents, said Daniel Baldassarre, an assistant professor at the State University of New York at Oswego, who was not involved in the study. "If I didn't tell me the background and just showed me a picture of this hybrid bird, I would probably have guessed the parent species." Although the bird appeared healthy, we didn't know if it would reproduce. It is not uncommon for hybrids to be sterile, especially in offspring that are not closely related. Only time will tell if this hybrid bird can pass on its unique genes. Hybrids, such as this bird from the rose-breasted white-breasted tanager and the scarlet tanager, illustrate how difficult it is to define a species, Baldassarre said. A species is generally defined as a group of organisms, consisting of individuals capable of exchanging genes or interbreeding. While the existence of hybrids may seem contrary to this definition, things are not that simple. "Species are real, but people like to argue about how to define them. It's a very confusing concept," Baldassarre said. More to be discovered While highly differentiated bird hybrids are thought to be rare, "more and more hybrids are emerging now," Baldassarre said. "Birds often interbreed, so the more we looked, the more we found." While only 16 percent of birds have records of interbreeding with other birds in the wild, it's likely that there are more hybrids than we thought. Finding every hybrid that spontaneously emerges is a daunting task, but with the help of bird-watchers like Gosser, it's possible. "A lot of these hybrids were discovered because someone was watching and saw a strange, 'hybrid-like' bird," Baldassarre said. "It's a once-in-a-lifetime finding a hybrid bird, especially one whose parent species is known to have never mate," Gosser said. "But I find it's always good to look closely at each bird because we never know what to expect. I will definitely keep my eyes open and pay attention to everything around me." (Translator: Sky4)