@owl_lady(Victoria Solovyeva): A pair of mated Little Owls has lived with us for almost 13 years. We named them Buriyan and Metel. We tried every method, but they never produced offspring, which caused us to joke that Buriyan wants children very badly but Metel is a 'child-free' woman. Then Buriyan died out of old age and Metel got a new roommate — Athena.
After that, two years ago I brought Metel to a regular check-up, which confirmed my suspicions. Metel was a male. Both Metel and Buriyan were males. He had testicles, but in all of the previous x-rays we didn't notice them. This time, however, the check-up was done in his mating season and he has been in close proximity to an actual female Little Owl Athena, which caused his testis to enlarge and appear on the x-ray.