Quote Originally Posted by chris-uk View Post
Most occurrences of cross-breeding I remember reading about have been between sub-species and therefore intergrades, @s opposed to crosses between species to make hybrids.
Crosses on the subspecies level aren't intergrades, they're hybrids. Intergrades are individuals that demonstrate intergradation, which is a phenomenon within population ecology in which subspecies are connected by populations that share characteristics with both.