Rare virgin births have been documented in some snake, shark, lizard, and bird species, but until now scientists have never found members of a normally sexual species reproducing asexually in the wild.
They captured pregnant copperhead and cottonmouth female pit-vipers from the field, where males were present.
The snakes gave birth, allowing the scientists to study the physical and genetic characteristics of the litters.
Of the 22 copperheads, the scientists found one female that must have had a virgin birth.
Another single virgin birth occurred within the 37 cottonmouth litters.
“I think the frequency is what really shocked us,” said Prof Booth.