Scientists in Texas confirmed the existence of a uncommon hybrid chook, the offspring of a inexperienced jay and a blue jay.
It’s one of many first identified circumstances of local weather change driving two species into the same range and creating a brand-new hybrid.
Climate Change Brings Unlikely Bird Parents Together
Biologists at The University of Texas at Austin have documented an unusual bird that appears to be the offspring of a green jay and a blue jay. They believe this may represent one of the first known cases of a hybrid animal arising in the wild because of recent shifts in climate. Although these two parent species are separated by about 7 million years of evolution, their habitats did not overlap until only a few decades ago.
“We think it’s the first observed vertebrate that’s hybridized as a result of two species both expanding their ranges due, at least in part, to climate change,” said Brian Stokes, a graduate student in ecology, evolution, and behavior at UT and first author of the study.
Stokes pointed out that most previous vertebrate hybrids were linked to human influence, such as invasive species introductions or one species encroaching on another’s territory (for example, polar bears and grizzlies). In this case, however, both parent species expanded their ranges at the same time as weather patterns shifted, creating the opportunity for hybridization.
A Rare Hybrid Emerges in Texas
Back in the 1950s, green jays, which are tropical birds native to Central America, barely reached into southern Texas from Mexico. Blue jays, common across the eastern United States, extended only as far west as Houston. Encounters between the two were almost nonexistent. Over the following decades, though, green jays gradually spread north while blue jays extended west, and today their ranges overlap in the San Antonio area.
While studying green jays in Texas as part of his doctoral research, Stokes regularly scanned birding posts on social media to help locate potential field sites. This allowed him to find birds he could capture briefly, take blood samples from for genetic analysis, and release safely. One day, he came across a blurry photo of a striking blue bird with a black mask and white chest, shared by a woman in a suburb northeast of San Antonio. The bird looked somewhat like a blue jay but also distinctly different. Curious, Stokes accepted the woman’s invitation to visit her backyard and see the bird himself.
Caught in the Net: A Scientific Breakthrough
“The first day, we tried to catch it, but it was really uncooperative,” Stokes said. “But the second day, we got lucky.”
The bird got tangled in a mist net, basically a long rectangular mesh of black nylon threads stretched between two poles that is easy for a flying bird to overlook as it’s soaring through the air, focused on some destination beyond. Stokes caught and released dozens of other birds, before his quarry finally blundered into his net on the second day.
A Vanishing Act and a Return Years Later
Stokes took a quick blood sample of this strange bird, banded its leg to help relocate it in the future, and then let it go. Interestingly, the bird disappeared for a few years and then returned to the woman’s yard in June 2025. It’s not clear what was so special about her yard.
“I don’t know what it was, but it was kind of like random happenstance,” he said. “If it had gone two houses down, probably it would have never been reported anywhere.”
Confirming the Hybrid’s Parentage
According to an analysis by Stokes and his faculty advisor, integrative biology professor Tim Keitt, published in the journal Ecology and Evolution, the bird is a male hybrid offspring of a green jay mother and a blue jay father. That makes it like another hybrid that researchers in the 1970s brought into being by crossing a green jay and a blue jay in captivity. That taxidermically preserved bird looks much like the one Stokes and Keitt describe and is in the collections of the Fort Worth Museum of Science and History.
“Hybridization is probably way more common in the natural world than researchers know about because there’s just so much inability to report these things happening,” Stokes said. “And it’s probably possible in a lot of species that we just don’t see because they’re physically separated from one another and so they don’t get the chance to try to mate.”
What’s in a Name? The Case of the Unnamed Bird
The researchers did not opt to name the hybrid bird, but other naturally occurring hybrids have received nicknames like “grolar bear” for the polar bear-grizzly hybrid, “coywolf” for a creature that’s part coyote and part wolf and “narluga” for an animal with both narwhal and beluga whale parents.
Reference: “An Intergeneric Hybrid Between Historically Isolated Temperate and Tropical Jays Following Recent Range Expansion” by Brian R. Stokes and Timothy H. Keitt, 10 September 2025, Ecology and Evolution.
DOI: 10.1002/ece3.72148
The scientists’ work was supported by a ConTex Collaborative Research Grant through UT System, the Texas EcoLab Program and Planet Texas 2050, a University of Texas at Austin grand challenge initiative.
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