Impact of Snowfall on the Utah Preventive Aerial Hunting Program

Authors

Kimberly K . Wagner, United States Department of Agriculture, Animal Plant Health Inspection Service, Wildlife Services
Michael R. Conover, Jack H. Berryman Institute for Wildlife Damage Management, Department of Fisheries and Wildlife, Utah State University, Logan

Date of this Version

1999

Comments

Published in Wildlife Society Bulletin 1999, 27(3):943-945.

Abstract

Aerial hunting is one of the tools used by wildlife managers to reduce predation by coyotes (Canis latrans) on livestock and wildlife (Guthery and Beasom 1977, Sterner and Schumake 1978, Stout 1982. Smith et al. 1986). In research conducted by Wagner and Conover (1999), areas with preventive aerial hunting had fewer confirmed and estimated lamb losses to coyote predation and required significantly fewer hours of additional corrective predation management than areas without aerial hunting. Aerial hunting is perceived to be especially valuable for large areas and areas with rough terrain and limited access (United States Department of the Interior (USDI) 1973a,b; Sterner and Schumake 1978; Wade 1978). However, use of this technique is limited by many variables, including funding, helicopter availability, and environmental requirements for safe and effective hunting (Wade 1976, USDI 1978).
During aerial hunting, coyotes are shot by hunters from aircraft. Due to their greater maneuverability, helicopters are preferred to fixed-wing aircraft for aerial hunting in the steep, mountainous terrain used for summer grazing in the Intermountain West (Wade 1976, USDI 1978). Aerial hunting is generally restricted to winter, when cold, dense air is optimal for safe flying conditions and plant foliage is minimal. Snow cover improves hunting efficiency because coyotes and their tracks are more conspicuous on a white background (C. J. Packham, USDI, unpublished report, 1973: Wade 1976). The efficiency of aerial hunting can also be improved by coordinating the efforts of the team in the aircraft with ground personnel using sirens and calls to help locate coyotes (Wade 1976). However, in many areas of the Intermountain West, access from the ground is unavailable or impractical and tracking in snow becomes especially important. Consequently, personnel of the United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services in the Intermountain West generally prefer to hunt within 48 hours of a snowfall when winds have been low, to facilitate tracking (J. Winnat, Utah Wildlife Services, personal communication).
Because of the importance of snow in aerial hunting programs in the Intermountain West (C. J. Packham, USDI, unpublished report, 1973), we examined the impact of low snowfall on aerial hunting as used by Wildlife Services personnel in Utah National Forests. Low snowfall can impact the programs by reducing the extent, intensity, or efficiency of aerial hunting. If aerial hunting teams always select optimal conditions, there may be a decrease in the extent of aerial hunting but no decrease in its intensity or efficiency. In contrast, if hunting teams accept less-desirable hunting conditions during years with low snowfall, there might not be a decline in the extent of aerial hunting, but there might be a decline in its intensity or efficiency.