Someone on the BBC lunchtime news today referred to a dog fox.
The word dog is both generic and applied to both sexes, as well as being used to describe a male. Only context reveals whether a person is talking about dogs in general or a male dog, as opposed to a bitch.
Is it not the same with fox and vixen? Or are we required, when specifying a male fox to use dog fox?
The OED would not appear to recognise any sense of fox as referring to a male only, in the way that it does with dog.
Are there other species where the gender distinction is only achieved by reference to a different genus?