onsiderable concern has arisen in recent years regarding the relative proportions of mule deer relative to white-tailed deer, especially in the Trans-Pecos region. Whitetails have successfully expanded their range and population destinies into some areas that were once inhabited only by mule deer. White-tailed deer are now common on much of the mule deer range in Texas, and whitetails have essentially the same diet as mule deer when the two species share common vegetation types. The expansion of whitetails is correlated with an increase in brush density over the last 25 years. As the habitat becomes more brushy, it becomes more suitable for whitetails than for mule deer. The two species tend to segregate themselves somewhat, as mule deer prefer the rougher canyons and breaks while the whitetails are more common in the brushy draws.
Mule and white-tailed deer can and do hybridize. Both parental mating (i.e.,mule deer buck X white-tailed doe, and mule deer doe X white-tailed buck) have been documented, but the former cross (mule deer buck X white-tailed doe) seems to be most common in the wild. Hybrids can sometimes be recognized by intermediate antler characteristics and tail coloration, or by the appearance of the metatarsal gland. This gland, which is located outside the rear hock above the hook, is typically about 3/4-inch long in whitetails and about 3 inches long in mule deer. Hybrids tend to have glands about 2 inches long. Hybrids appear to have at least a limited degree of fertility. Most hybrid deer are apparently absorbed into the mule deers’ gene pool.
Most ranchers with mule deer want to protect the genetic integrity of the mule deer and deter crossbreeding. However, other than implementing higher harvest rates for whitetails, there is little that can be done. Clearing large areas of brush to promote more mule deer is not generally economically feasible because of high treatment costs. A good range management program that slows the encroachment of brush may be the best solution to the problem.