An abstract:
A coyote population model is proposed from current estimates of density, reproduction, food availability, population structure, and mobility. Densities of 0.5 to 1.0 coyote per square mile are frequently suggested, with occasional estimates of 4.0 or more per square mile.
Reproductive rates fluctuate as functions of the proportion of females that ovulate, the average number of ova shed, and in utero viabilities. Average litter sizes of 4.3 to 8.9 seemed to be inversely related to population density.
Studies of captive coyotes indicate that 35 percent may experience estrus in their first year, the remainder not becoming sexually mature until 20 to 22 months of age. In Kansas, Gier (1968) reported that in some years less than 10 percent of this age group becomes sexually active but that when rodents are abundant, as high as 70 percent of the short yearlings may breed.
This is in reasonable agreement with estimates that under conditions in South Texas, about 50 percent of the population normally breeds, producing average litters of 4.6 to 5.2 young.
Age structure of unexploited populations suggests a 40 percent annual mortality for coyotes over 1 year of age, with relatively high survival rates between 4 and 8 years of age.
On the basis of field examinations of coyotes recovered from standard coyote-getter lines in high density areas, it appears that juveniles comprise about half the full populations. In southern New Mexico, Rogers (1965) found that pups comprised 53 percent of the fall population.