Without genetic studies, it is impossible to distinguish between a pure Blacktail vs. a Benchleg hybrid. Phenotype vs. Genotype:
Phenotype: The outward appearance of an organism; the expression of a genotype in the form of traits that can be seen and measured, such as hair or eye color.
Genotype: the genetic makeup of an organism or group of organisms with reference to a single trait, set of traits, or an entire complex of traits.
Muleys and Blacktail are genotypically different. You can do gene studies and tell which is which. Characteristics you observe on the animal you are looking at in your binoculars are the phonotypical expressions of genes, which does not imply that they are one animal or the other in the high mountain areas. In those areas where the muley/blacktail ranges intersect, then there is almost way to tell if it is a pure blacktail without genetic studies of the tissues. If it looks like a blacktail and the antlers are not way too big and the tail looks right, then the "judges" will call it a blacktail. In my mind, almost all deer living in the Cascades are a mix of the two species.
Genetics studies have shown that mulies came from ancestors of blacktail deer. Separation of environments and likely climate (ice age glaciers) were responsible for the initial differentiation of the two species. Now, the ranges intersect more easily, so the two species can mate and create hybrids. This is certainly not a new phenomenon, just one that has left us silly humans trying to figure out what is really going on with these deer.
It's a great demonstration of evolution. Coastal Blacktail seem to have smaller antlers because of the thick impenetrable environment that they live in. Can you imagine a big muley buck trying to get through the thick junk with those big antlers? With more space and less heavy brush to navigate, larger antlers were more possible for muleys and eventually selected for by the does that bred with the bucks with those traits. Environments in the highland areas can support both breeds and creates the opportunity for hybrids. That's my
Back to the question at hand - 3nails has shown the results of how good the hunting can be. Many, many examples of great bucks coming out of high meadows and rocky ridgeline areas can be found. Off-season scouting is the key to finding them.
