Hybrid partridges?

The red-legged partridge is a bird species in New Zealand that has been liberated a number of times, but has yet to become genuinely established in the wild. Despite this, it is still featured in field guides to NZ's birds.

Its close relative, the chukor/chukar partridge, is an uncommon established species in the South Island. It is closely-related and very similar-looking to the red-legged partridge. Both species are commonly kept in captivity here.

I have reason to believe that the red-legged partridges kept in New Zealand, however, are not genetically 'pure', and carry some chukor blood, due to the fact that first-generation hybrids between the two, at least, have been bred in captivity.

As previously stated, the red-legged partridge is very similar-looking to the chukor (though not as similar to the chukor as the rock partridge). They are most easily distinguished from chukors by their streaked necks; an obvious feature of their phenotype. Still, I am sure that even this could be 'missed', meaning that unintentional hybrids between chukors and red-legs could be bred in captivity.

What I don't know, however, is whether or not chukors and red-legs are fully interfertile. My assumption is that they are, meaning that first-generation hybrids and all of the following generations are fertile, meaning that it is possible for pure-looking red-legs and chukors to carry the blood of both species. It is possible, however, for closely-related species not be fully interfertile; an example of this is the two Aix ducks.

Another important part of my assumption that I know nothing about is what the first-generation hybrids look like. If they can't be told apart from 'pure' specimens of one of the two species, then the captive population of one of the two partridge species becoming genetically 'swamped' by the blood of the other species is practically inevitable.

If DNA testing is done and NZ's red-legged partridges are found to carry chukor blood, perhaps some will decide that they should not be treated as an actual species in New Zealand.

But then, perhaps not. After all, the wild Lady Amherst's pheasants of the UK are/were considered to be fully acceptable as a species, but I have yet to see a photo of one that does not show obvious signs of golden pheasant hybridisation.