Biologists at The University of Texas at Austin have made a groundbreaking discovery, reporting the existence of a bird that is the natural result of mating between a green jay and a blue jay. This finding is significant as it may represent one of the first instances of a hybrid animal emerging due to recent climate change. The two parent species, which have been separated by roughly 7 million years of evolution, did not even overlap in their geographic ranges until only a few decades ago.
According to Brian Stokes, a graduate student specializing in ecology, evolution, and behavior at UT and the lead author of the study, this case could be the first observed instance of a vertebrate hybrid forming as a result of both species expanding their ranges due, in part, to climate change. Stokes pointed out that prior vertebrate hybrids often resulted from human activities, such as the introduction of invasive species or the recent expansion of one species into the range of another. A well-known example includes the hybridization of polar bears and grizzlies. However, this new case appears to have arisen from shifts in weather patterns that prompted both parent species to move into overlapping territories.
In the 1950s, the geographic range of green jays, tropical birds predominantly found across Central America, barely extended into south Texas. At the same time, blue jays, which inhabit temperate regions throughout the Eastern U.S., were only observed as far west as Houston. For many years, these two species rarely came into contact. However, as climate patterns have shifted, green jays have moved northward while blue jays have expanded westward, leading to their ranges converging around San Antonio.
As a Ph.D. candidate focused on green jays in Texas, Stokes frequently monitored various social media platforms where bird enthusiasts share their sightings. This practice often helped him locate birds for research purposes. One day, he stumbled upon a photo of an unusual blue bird with a black mask and a white chest posted by a local birder in a suburb northeast of San Antonio. The bird bore a resemblance to a blue jay but was distinctly different.
The backyard birder invited Stokes to observe the bird in person. "The first day, we tried to catch it, but it was really uncooperative," Stokes recounted. However, luck turned in their favor the following day when the bird accidentally got tangled in a mist net—a long rectangular mesh of black nylon threads designed to capture flying birds. After catching and releasing numerous other birds, Stokes finally managed to trap this intriguing specimen.
Following the capture, Stokes took a blood sample from the unique bird and banded its leg for future identification before releasing it back into the wild. Interestingly, the bird vanished for a few years, only to reappear in June 2025 in the same yard where it was originally spotted. "I don't know what was so special about her yard," Stokes commented, adding that if the bird had wandered just a couple of houses down, it likely would have gone unreported.
Through analysis conducted by Stokes and his faculty advisor, Professor Tim Keitt from the Department of Integrative Biology, the bird was confirmed to be a male hybrid offspring of a green jay mother and a blue jay father. This finding is reminiscent of another hybrid created in the 1970s by researchers who crossbred green jays and blue jays in a controlled environment. That specimen, preserved through taxidermy, closely resembles the hybrid described by Stokes and Keitt and is part of the collections at the Fort Worth Museum of Science and History.
Stokes suggests that hybridization in the natural world is likely far more common than current research indicates. "There’s just so much inability to report these things happening," he said, noting that many potential hybrids go unnoticed due to physical separation between species, which limits their opportunities to mate. Though the researchers chose not to assign a name to the hybrid bird, other naturally occurring hybrids have received playful nicknames, such as grolar bear for the polar bear-grizzly hybrid, coywolf for the coyote-wolf mix, and narluga for the narwhal-beluga hybrid.
