INTRINSIC AND EXTRINSIC FACTORS INFLUENCING COYOTE PREDATION OF SMALLMAMMALS IN YELLOWSTONE-NATIONAL-PARK

We examined the intrinsic (age, sex, and social status) and extrinsic factors (snow depth and hardness, temperature, cloud cover, wind speed , and habitat) influencing coyote (Canis latrans) predation of small m ammals in Yellowstone National Park, Wyoming. We observed 54 coyotes ( 49 residents from 5 packs, plus 5 transients) for 2507 h from January 1991 to June 1993. We observed 6433 prey detections by coyotes during which coyotes made 4439 attempts to capture prey, resulting in 1545 su ccessful prey captures. The age of the coyote influenced prey-detectio n rates, predation attempts, and capture rates, plus the proportions o f prey attacked after being detected and capture success. Pups had hig her prey-detection rates and higher attempt rates than alphas and beta s, but capture rates were similar. Snow depth and hardness and habitat type were factors influencing detection rates, predation attempt rate s and capture rates. Coyotes hunted mainly in mesic meadows and shrub- meadows, where prey-detection rates, predation attempt rates, and capt ure rates were highest. Snow depth influenced coyote predation on smal l mammals, prey-detection rates, predation attempt rates, and capture rates being highest in low snow cover and lower in deeper snow. Our fi ndings indicated that young, inexperienced coyotes detected and attack ed small mammals at a higher rate than older coyotes. Yearlings and ad ults were more selective, and thus detected and attempted to capture p rey at a lower rate than pups. Overall, however, pups and older coyote s captured similar numbers of prey per hour.