Population dynamics and life-history evolution depend heavily on fecundity, which, in the coyote (Canis latrans), can vary substantially according to environmental conditions. Although well studied in the central part of its range, little is known about coyote reproduction in the Mediterranean climates associated with Pacific-coastal North America. I used postmortem examinations of 441 coyotes collected throughout central California to investigate reproduction, including age-specific fecundity, breeding synchrony and seasonality, and relationship to nutritional condition. Reproductive parameters did not vary significantly among sampling locations. Overall, numbers of corpora lutea averaged 6.9 (range = 4–11) and litter size (based on fetuses or placental scars) averaged 6.6 (range = 1–12) among postpartum females. The number of corpora lutea increased with maternal age, and litter size also increased with age to 6 years but decreased in older females. Most (77%) adult females became pregnant and 13% of 1st-year females became pregnant. During January–March, 96% of adult males and 68% of 1st-year males had reproductive testes. Reproductive signs in both sexes occurred 3–4 weeks later in 1st-year coyotes than in adults. Parturition dates, which decreased with increasing maternal age, ranged from 9 March to 7 May, indicating that estrus occurred from early January to late March. Of 1st-year coyotes, reproductive individuals were larger during the breeding season and had higher marrow fat indexes than nonreproductive ones (both sexes). After the breeding season, 1st-year females that did not breed (become pregnant) had similar body mass to 1st-year and adult coyotes that did breed, and adult females that did not breed were larger than the others but similar to the weight of breeders during the breeding season. Thus, whether yearlings attained breeding condition apparently depended on their nutritional condition. Adult fecundity estimates were among the highest reported for coyotes.
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