The officials at the Arkansas Game and Fish Commission have described the finding as incredibly rare. "I can't even say it's one in a million - it's probably more than that," said Karen Rowe, an ornithologist with the Arkansas Game and Fish Commission. "There's just very little to no records of such a thing," she added. The birds, found in White County, fell out of a nest as a healthy sibling flew off to learn how to hunt with its parents, said Rowe.
The birds first appeared to have only three legs, but further examination found a fourth leg tucked up underneath the skin connecting the pair.
According to Rowe, the landowner who found them probably kept the birds for a day before calling wildlife officials.
By the time officials arrived, the birds were not eating. One died early Friday and a veterinarian later put the other one down.
"Finding conjoined birds is rare because they likely die before being discovered," said Rowe.
X-rays of the pair found each bird was fully formed. Rowe said that the birds would have had to come from a double-yolk egg.
Barn swallows can live for several years, though the conjoined twins might not have lived that long even if they had been separated.