NATIONAL PARK SERVICE Ecology of the Carmen Mountains White-Tailed Deer

The ecology of Carmen Mountains white-tailed deer (Odocoileus virginianus carminis) in Big Bend National Park, Texas, was examined between June 1972 and April 1974. Distribution, habitat, food habits, competition with mule deer (O. hemionus crooki), and predator—prey relationships are discussed.

Approximately 580 Carmen deer inhabit the Chisos Mountains in the park. Their range extends to isolated mountains outside of the park and into Mexico but the Chisos Mountains provide the main habitat in the United States. Carmen deer were found most often in pine—juniper—oak (Pinus spp.—Juniperus spp.—Quercus spp.) associations above 4,500 feet (1,373 m). Two components of whitetail habitat were found on all ranges: free-standing water and dense vegetation.

Based on the contents of 25 rumens, forage consumption included browse (35%), succulents (28%), forbs (14%), and grasses (4%). Unidentified food items made up 19% of rumen contents. Lecheguilla (Agave lecheguilla) and pricklypear (Opuntia engelmannii) were used the most, comprising 17% and 11% of the diet, respectively. Succulents provide a source of moisture and are important throughout the year, especially during dry months.

Mule deer inhabit the Chihuahuan Desert surrounding the Chisos Range and overlap with Carmen deer on lower foothills. An important habitat-separating mechanism between the two species appeared to be topography. Forage competition was precluded due to an abundance of commonly used food items but interference between opposite species may influence habitat selection.

Of whitetail deaths recorded, 24 were of undetermined causes or related to accidents, and 25 were killed by mountain lions (Felis concolor). Analysis of 161 lion droppings indicated that 70% of their diet was deer. Other predators of Carmen deer include bobcats (Lynx rufus) and coyotes (Canis latrans).

A single factor could not be isolated which regulated deer distribution and population levels, but interspecific behavior, habitat preference and topography, water availability, and predation combined were the most likely influences.