This research involved 2 radiotelemetry field experiments and a large-scale survey of reproduction in central California. The first radiotelemetry study investigated the behavior of coyotes relative to their territory boundaries, a study that was just published. The second radiotelemetry study focused on the benefits of paternal care to females. Although it is commonly assumed that male care of pups evolved because it enhances fitness of fathers via viability of their offspring, it is also possible that male care evolved in response to sexual selection. A prediction of this latter hypothesis is that male care of pups benefits the mothers. We investigated this prediction by comparing female coyotes with mates present to those with mates that had been removed after parturition. No females abandoned litters in response to removals of mates. Females (n = 4) apparently spent more time foraging after mates were removed, as indicated by proportionally fewer radiolocations at den sites and greater activity ( d = 13%) associated with radiolocations away from den sites. At the end of pup-rearing, mateless females (n = 3) were in poorer physical condition than mated females (n = 3). These observations suggest females compensated for absences of their mates at costs to their own future reproductive success, supporting the prediction that paternal care increases fitness of females. (note: this study did not involve removal of coyotes but, rather, took advantage of removals that occurred during routine predator control activities occurring independently of the study.) In large-scale study, I used necropsies of ~500 coyotes from 4 ecological regions of California to investigate seasonal timing and productivity in reproduction of male and female coyotes as a function of age and body condition. One particularly interesting finding was that older females had litters earlier in the year than younger females. I speculate that earlier reproduction may confer an advantage to the offspring of older females, serving to prolong age-specific fitness.”

Sacks, B. N. 2005. Reproduction and body condition in California coyotes (Canis latrans). Journal of Mammalogy 86:1036-1041..

Sacks, B. N. and J. C. C. Neale. 2001. Does paternal care of pups benefit breeding female coyotes (Canis latrans)? Southwestern Naturalist 46:121-126.

, J. C. C., B. N. Sacks, and K. M. Blejwas.  2007.  Coyote movements relative to territory boundaries: An experiment in the field.  American Midland Naturalist 158:162–167