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Two groups of coyotes in which genealogical relationships were known were studied in the Grand Teton National Park, outside of Jackson, Wyoming, U.S.A., from 1977-1982. One group, a pack consisting of parents and some non-dispersing and non-breeding offspring, defended a territory and the food (mainly elk carrion) contained within it, especially during winter, and also had helpers at den sites (5 of 6 were males). The other group, a mated resident pair, all of whose young dispersed during the first year of life, did not defend a territory and never had helpers at dens. Delayed dispersal and retention of some offspring as helpers was related to the presence of an abundant, clumped, and defendable winter food resource. Dispersing yearlings suffered higher mortality than did non-dispersing individuals.

Litter size was the same for the pack and resident pair; litter size was not significantly correlated with number of adults in the group or with the number or percentage of pups that survived to 5-6 months of age. The presence of pack helpers was not significantly correlated with pup survival, although there was a positive correlation (rs = +0.37) between the number of adults attending a den(s) and pup survival. Helpers rarely fed pups and their presence had no appreciable effect on juvenile weight. Helpers partook in den-sitting (pup-guarding), but they did not reduce the amount of time that parents spent at den sites. Helpers also actively initiated and took part in territorial and food defense. The proportion of times that pack members initiated defense was inversely related to intruder density (r = - 0.94).

It appears that the main advantage of helpers' presence during the time when pups are around is increased protection of young against potential predators. Helpers' sharing of territorial and food defense during winter also is important. From a helper's point of view (for example male B2-1), delayed dispersal from the natal area may increase the likelihood of inheriting a breeding area in which food resources are abundant; mating with a group member or unfamiliar individual is possible. Help may also be received from individuals to whom care had previously been provided. The positive, but non-significant, increase in pup survival associated with helpers' presence also must be considered. The risks associated with early dispersal, low initial reproductive success, and the low probability of inheriting a breeding area are related to observed individual dispersal polymorphisms in coyotes when ecological conditions, especially winter food supply, are sufficient to support a mated pair and some offspring.


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