Wild Grue Jay Hybrid Appears After a 1965 Zoo Warning

A male songbird netted in a San Antonio suburb in 2023 is the first wild offspring of a green jay and a blue jay ever documented. Blood tests showed a green jay mother and a blue jay father, two birds whose lines split at least 7 million years ago.

Warren M. Pulich and Rhonda M. Dellinger, describing a zoo-bred cross of the same pair, wrote in 1981 that wild hybrids were not to be expected. The new bird, unofficially nicknamed a grue jay, showed up in a yard where historically neither parent nested.

A 1965 Zoo Note Said Hybrids Were Not Expected

Fort Worth Zoo already knew the two jays could breed. A male green jay and a female blue jay produced a chick there on 17 June 1965, after a first clutch failed and a second of three eggs yielded one young. Dellinger saw that bird on exhibit on 18 September 1977, when it was more than 12 years old. It died on 28 January 1978 and went into a museum collection.

The 1981 write-up in The Wilson Bulletin treated a wild repeat as almost fanciful. At that time the breeding ranges still sat about 200 km apart, a gap the authors treated as a hard wall.

The possibility of the Green Jay and the Blue Jay occurring naturally together during the breeding season is remote, so that hybrids are not to be expected in the wild.

Warren M. Pulich and Rhonda M. Dellinger, The Wilson Bulletin, 1981

That line is now the sour joke inside the nickname. The hybrids are not to be expected in the wild warning was sound for the maps those authors had. The maps moved. The zoo bird’s parentage also ran the other way from the San Antonio bird: green father, blue mother, the reverse of the wild cross.

A Suburb Neither Jay Used to Occupy

Brian Stokes, a doctoral candidate in ecology, evolution, and behavior at The University of Texas at Austin, and Tim Keitt, an integrative biology professor there, put the wild bird in Universal City, a suburb northeast of San Antonio. Stokes has said that at capture it was about a year old, so the pairing itself likely happened around 2022, in a neighborhood that did not sit inside either species’ mid-century range.

Green jays are tropical corvids (Cyanocorax yncas) whose United States toehold used to be the lower Rio Grande. Blue jays (Cyanocitta cristata) are temperate birds of the eastern states; in the 1950s they were uncommon west of Houston. The hybrid was found where, Stokes has said, you would not historically have found either parent.

THE TWO GREEN-BLUE CROSSES

The university’s own note on a rare hybrid identified in a San Antonio suburb is careful on the climate claim. Stokes called it the first observed vertebrate hybrid that followed both parents expanding their ranges, due at least in part to climate. He has also separated it from polar-grizzly “pizzly” bears, a case in which one species pushed into the other’s remaining ice and tundra.

Stokes Needed Two Days and a Mist Net

Stokes already trapped green jays for blood work and watched birder groups for odd birds. The first lead was a grainy photo, posted by a woman in that suburb, of a blue-looking jay with a black mask and a white chest. Jente Ottenburghs, who tracks bird hybrids, later wrote that the report first circulated in the Facebook group TEXBIRDS. The homeowner invited Stokes over.

“The first day, we tried to catch it, but it was really uncooperative,” Stokes said. “But the second day, we got lucky.” A mist net, a black nylon mesh birds often fail to see, finally held it after he had already pulled dozens of other birds out of the same set. He took a quick blood sample, banded the leg, and let it go.

The bird then vanished for a few years and came back to the same yard in June 2025. Stokes still cannot explain the lot. “If it had gone two houses down, probably it would have never been reported anywhere,” he said. The whole proof chain runs through one feeder, one Facebook thread, and one graduate student’s habit of lurking in birder groups. That is a thin net for a claim now traveling under a coined name.

FROM A ZOO CAGE TO A SAN ANTONIO YARD

1. 1950s: Green jays barely reach south Texas from Mexico; blue jays are uncommon west of Houston.
2. 17 June 1965: Fort Worth Zoo hatches a green-blue chick from a known pair.
3. 1981: Pulich and Dellinger publish the zoo bird and put the wild breeding ranges about 200 km apart.
4. 2000 to 2023: eBird records of the two species overlapping in Texas climb.
5. 2023: A TEXBIRDS photo leads Stokes to the Universal City bird; he bands it on the second day.
6. June 2025: The banded bird returns to the same yard.
7. 10 September 2025: Stokes and Keitt publish the genetic identification.

Work on the paper was supported by a ConTex Collaborative Research Grant through the UT System, the Texas EcoLab Program, and Planet Texas 2050, a University of Texas at Austin grand-challenge project.

What Did the Blood Tests Show?

Stokes and Keitt’s intergeneric hybrid after a recent range expansion appeared in Ecology and Evolution on 10 September 2025. Mitochondrial DNA matched green jays from Texas, which traces the mother. Nuclear DNA carried a mix of Cyanocitta and Cyanocorax lineages. Together those results mark an F1 cross, a first-generation offspring, not a later backcross.

The plumage did not melt the two parents into a muddy average. Ottenburghs, quoting the paper, called the look “codominant intermediate,” with distinct traits from each species sitting side by side. The body and tail read as blue jay, including black-and-white tail bands. The face carries a larger black mask, closer to a green jay. The chest is white. In the field it honked like a blue jay, then added green-jay bill-clicks and a low two-tone rattle.

TRAITS THAT GAVE THE BIRD AWAY

• Face: A wide black mask more like a green jay than a blue jay.
• Body and tail: Blue-jay shape, turquoise tones, and black-and-white tail bands.
• Voice: Blue-jay honks plus green-jay rattles and bill-clicks.
• DNA: Texas green-jay mitochondria and mixed nuclear DNA from both genera.
• Sex: Male, so in birds the sex more often able to sire young if a later pairing happens.

Jamie Alfieri, an evolutionary biologist at the University of Iowa who was not on the study, reached for scale rather than a nickname. “It’s just a really long time. I mean, I don’t know how else to say that. It’s a really big number,” she said of the split. Most wild bird hybrids involve much closer cousins. The paper counted 11 reported hybrids inside New World jay genera and only two previous crosses between genera, neither of them this pair.

Two Range Shifts Met in the Same Yards

Press notes leaned on climate. The paper, and Stokes and Keitt in interviews, split the labor. Green jays rode warmer winters north. Blue jays followed people, oaks, and feeders west. The contact zone is a neighborhood, not a wilderness frontier, and that is the part the cute name leaves out.

THE RANGE COLLISION IN BRIEF

• Old wall: About 200 km still separated the breeding ranges when the zoo bird was described in 1981.
• Green-jay move: The paper says the species has shifted as much as 2 degrees of latitude in a few generations.
• Speed: Keitt has called the green-jay push “quite quickly, maybe a 20-year-period.”
• Blue-jay move: Populations built in Austin and San Antonio as yards grew oaks and feeders.

Green Jays Followed the Warmth

Field guides still treat green jays as a southern Texas specialty, common in mesquite, ebony, and hackberry woods along the lower Rio Grande. That picture is late. Stokes has described the old northern limit around Laredo and King Ranch into the 1960s, with birds now turning up toward San Antonio, Uvalde, and Del Rio, and also easing into coastal oaks around Goliad and Victoria.

The paper hypothesizes that fewer long freezes lifted a lid that used to pin the species in deep south Texas. Experimental proof of that climate link is still thin, which the authors admit. The direction of the move matches a warmer southern Texas, and it matches a larger pattern of tropical-margin birds sliding north.

Blue Jays Followed the Neighborhood

Blue jays tell a more domestic story. Keitt has said they are tracking people and the rich food of suburbs. Stokes has pointed to feeders, artificial water on ranches, and large deciduous trees, especially oaks planted in yards. Those are land-use changes, not a simple thermometer reading, and they pulled a temperate jay west into towns that once sat in a gap.

Both species now use the same feeding stations. Ottenburghs compared that subsidy to other feeder-driven mixes, including hummingbirds. The San Antonio bird is less a wilderness accident than a product of warmed winters plus birdseed. A coal-mine joke writes itself, and it traveled with the photos, because a single odd jay is easier to love than a contact zone made of lawns.

Researchers Will Not Call It a Species

Stokes and Keitt did not name the hybrid. Other unofficial mashup names already float around different animals, from grolar bears to coywolves to narlugas, and the authors left “grue jay” off the paper. Ottenburghs went further in a February 2026 note, stressing that the Texas bird is not a hybrid species, a point several write-ups fumbled. In a 2021 review he had already argued that hybridization events expected to keep rising as people keep changing habitat and climate.

Keitt has said he doubts blue jays and green jays will collapse into one new species. The San Antonio bird also seemed to be on its own, even though both parents are highly social; nearby blue jays may have treated it as not-quite-flock. Why the original pair crossed the line is still a guess. Keitt has floated novelty in song and looks. Another reading is bleaker: two birds at the thin edge of their ranges, short on mates of their own kind.

So buckle in, folks. We’re going to see very different outcomes.

Tim Keitt, integrative biology professor, University of Texas at Austin

Stokes has said mixing of this kind is probably common and under-reported, because most animals never get a Facebook post and a mist net. The banded male could, in principle, breed; in birds, hybrid males are often the sex more likely to remain fertile. No nest of his has been documented. As of the 2025 paper, he is still one animal, not a population.

In June 2025 that banded bird walked back into the same San Antonio yard. The nickname makes it sound like a mascot. The 1981 authors, staring at a 200 km gap, thought this pairing would stay inside a zoo. The gap closed in the feeders and oaks of a suburb that used to hold neither jay.

Frequently Asked Questions

Is the Texas Grue Jay a New Species?

No. Stokes and Keitt did not assign a species name, and unofficial labels such as grolar bear, coywolf, and narluga already exist for other mixed animals without making them species. A hybrid species would need a self-sustaining population with its own evolutionary path, which a single banded male does not provide.

Are Blue Jays and Green Jays in the Same Genus?

No. Blue jays sit in Cyanocitta and green jays in Cyanocorax, which is why the paper calls the bird intergeneric. Among New World jays the authors found only two earlier between-genus reports, California scrub-jay × Steller’s jay and blue jay × Florida scrub-jay, both involving splits of about 6.8 million years.

Where Is the Older Captive Hybrid Now?

The Fort Worth Zoo bird, hatched 17 June 1965, died on 28 January 1978 after more than 12 years and was donated to the vertebrate collection that later placed a taxidermied specimen in the Fort Worth Museum of Science and History. Stokes and Keitt wrote that this preserved bird looks much like the San Antonio hybrid, even though the zoo parents were reversed.

How Many Eggs Did the 1965 Zoo Pair Lay?

Pulich and Dellinger recorded two clutches. The first failed. The second had three eggs laid on 30 May, 31 May, and 1 June 1965, and only one chick hatched; it was then taken from its parents and hand-reared before going on exhibit with other jays.

As of the 2025 paper, that banded male is the only wild green-blue jay hybrid on record. The yards that fed both parents are still there, and so is the overlap that made him possible.