Potential Effects of Ecosystem Management on Cervids Wintering in Ponderosa Pine Habitats

Abstract

Elk (Cervus elaphus), mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) winter in ponderosa pine (Pinus ponderosa) habitat types on the Blackfoot Clearwater Wildlife Management Area (BCWMA) in western Montana. Natural fire has been excluded from these habitats during the 20th century, promoting growth of dense Douglas-fir (Pseudotsuga menziesii) and ponderosa pine understories. "Ecosystem Management" (EM) prescriptions for restoring natural processes in ponderosa pine types result in widely spaced mature trees, less Douglas-fir in forest overstories, and a substantial decrease of conifers in understories. Douglas-fir was the dominant forage item for both deer species on the BCWMA throughout the winters of 1991-1993, and remained the primary forage for white-tailed deer during a very mild winter in 1994 when other forages were widely available. Tree lichen (Alectoria sp.) was also important winter forage for deer and elk. A decrease in conifers of all size classes could reduce abundance and above-snow availability of lichen, coniferous forage and thermal cover. Of the three cervids, elk appeared least dependent upon canopy closure and coniferous forage. EM prescriptions may benefit elk (excluding security concerns) because of enhanced grass production and availability. Mule deer used habitats with sparse or dense overstory canopies, which provided no evidence that mule deer would benefit from decreased coniferous cover. White-tailed deer used habitats with dense canopies and were most likely to be affected at the population level by typical EM prescriptions. This could be problematic in western Montana where high white-tailed deer numbers may be an asset for recovering populations of scavengers and predators such as the bald eagle (Haliaeetus leucocephalus) and gray wolf (Canis lupus).