Date of Award:

5-1982

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Department name when degree awarded

Fisheries and Wildlife

Committee Chair(s)

Frederick G. Lindzey

Committee

Frederick G. Lindzey

Committee

Floyd Coles

Committee

Jim Gessaman

Committee

Fred Knowlton

Abstract

Diet of cougars (Felis concolor) was studied from December 1978 to August 1981, on a 4500 km2 study area near Escalante, Utah. Prey eaten was determined from analysis of 112 animals consumed as prey, and from 239 cougar scats. Mule deer (Odocoileus hemionus) were the major prey item, comprising 81% of biomass consumed. Lagomorphs, large rodents, and smaller predators were also important components. Cattle comprised <1% of the diet, although commonly grazed on the cougar's summer range. Adult male and juvenile (<1yr) mule deer were killed more often than expected, in fall (P<0.10) and in winter (P<0.005). Cougars were a major cause of mortality of adult deer (41% of all adult female deaths, 35% of male), but only 6% of mortality of juveniles. Selection of prey seemed to be a function of prey vulnerability, rather than one of active choice by the predator.

Motion-sensitive radio-transmitters were placed on 15 cougars, from 3 months to 7-9 years of age. Three parameters of the radio signal were used to determine activity levels during 6843 1-minute sampling periods: number of changes in pulse rate, predominant pulse mode, and signal integrity, based on 308 minutes of "known" acti vity. Cougars showed distinct crepuscular (sunrise, sunset ± 2 hrs) activity peaks (P <0.001). The 1 adult male was more active than females with older cubs and than older cubs, both of which were more active than females with smaller cubs and small cubs.

Estimates of energetic costs of basal metabolism, and of activity, growth, and reproduction were used in a predictive model of energy cost of free-existence. Information on dietary composition, live weight and energy content of prey animals, and assimilation efficiencies were used to provide estimates of the frequency at which deer were killed (deer/day) and consumed (kg/day). Single adults were estimated to kill 1 deer per 8-16 days. Females with 3 large cubs would kill 1 deer as often as every 2-3 days. A known population of 8 adult cougars was predicted to consume 417 deer per year.

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