IF two species can Hybridize and kept in captivity, I think the urge to mate is so strong they will mate with something not of their kind. Take the Liger as an example, that would never happen in the wild.
There have been cases of dog/wolf hybrids in the wild but very, very rare because wolves usually kill domestic dogs. It was a rare case a female dog was in heat and lived outside and a lone male wolf who had no pack mated with her but probably only because he was low rank and wanted to start his own pack and that was the only female he could find.
It's like the mantids, their kind is always around so hybrids rarely occur, in captivity forced mating putting them together makes it possible.