However, neither ovulation nor mating behavior was fully suppressed. A transient suppression of sexual behavior was observed, and in some cases, estrus appeared slightly lengthened. Pregnancy was averted in six females treated after ovulation, suggesting that appropriate timing of treatment proved crucial. We treated captive adult female coyotes in estrus with 0.01mg/kg estradiol benzoate (EB), either before (n=5) or immediately after ovulation (n=6), then documented reproductive outcome, physiological variables and behavioral responses, during and after treatment. Herein we describe a study examining the physiological effectiveness, health safety, and behavioral consequences following treatment of estrous coyotes with exogenous estrogen. Steroid hormones successfully control fertility in some species, but have been considered contraindicated in wildlife and canids in particular specific concerns include possible induction of aberrant behavior, or uterine and hematopoietic pathologies. Contraception, therefore, may represent a non-lethal solution for conflicts between coyotes and humans. But while dominant adults have been implicated as primary killers, depredation is reduced when coyotes are without pups. They are also opportunistic predators on domestic livestock and pets. Breeding is dominated by each pack's alpha male and female, and both sexes share responsibility for territory defense and pup-rearing. Coyotes (Canis latrans) are seasonally monestrous and form perennial pair-bonds.