Date of Award:

5-1976

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Department name when degree awarded

Wildlife Science

Committee Chair(s)

Frederic H. Wagner

Committee

Frederic H. Wagner

Committee

L. Charles Stoddart

Committee

Stephen Hibler

Committee

Stepehn Hoffman

Committee

John Weaver

Abstract

I estimated various demographic parameters of the coyote population in Curlew Valley, northern Utah and southern Idaho, during the period August 1972 through September 1974. Field work provided estimates of relative and absolute coyote densities and established causes of coyote mortality. Laboratory analyses of 866 coyote carcasses supplied information on sex and age ratios, ovulation frequencies, pregnancy rates, and litter sizes.

Annual ovulation frequencies and pregnancy rates for the entire population varied from 70 to 92 percent and 57 to 88 percent respectively. Age-specific ovulation frequencies varied from 63 to 91 percent, respectively, for pups and adults. Similarly, age-specific pregnancy rates varied from 53 to 100 percent for pups and adults respectively. Mean age-specific litter sizes were 6.0, 5.9, 6.5, and 6.2 for pups, yearlings, adults, and all ages combined, Reproductive rates appeared to be inversely related to coyote densities; hence, density-dependent processes operated in this population.

The sex ratio of denned pups (May) did not differ significantly from an expected 50:50 sex ratio. The pup sex ratio in the winter carcass collections differed significantly from 50:50 where as that of yearlings and adults did not.

The percentage of pups varied from 42 to 56 percent in the winter carcass collections. Ages of coyotes were determined by counting cementum annuli in longitudinal canine and lower first premolar sections. In addition to the conventional method of assigning ages, I developed a second method based on cementum thickness ratios. This method was necessary since my collections were obtained during the period of annulus formation. Hence it is possible to observe coyotes of the same age that display different numbers of annuli.

Both the relative- and absolute-density data revealed substantial short-term variation in coyote densities. Post-whelping, May coyote densities may have varied from 1.5 to 0.2 coyotes per square mile (0.6 to 0.08 coyotes per km2).

The mortality of coyotes 5 months old and older was almost entirely man-induced. Annual fall-to-fall population mortality varied from 42 to 82 percent. Similarly, estimated birth-to-fall pup mortality rates ranged from 41 to 72 percent, with the major losses probably occurring between birth and May. Coyotes are probably most susceptible to natural mortality during their first few months of life.

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