Reproductive activity in the peninsular pronghorn determined from excreted gonadal steroid metabolites

Fecal hormone monitoring was employed to better define annual patterns of reproductive steroid metabolites from a breeding pair of peninsular pronghorn (Antilocapra americana peninsularis) maintained at the Los Angeles Zoo. Notably in the female, increased excretion of estrogen metabolites occurred during the breeding season (Jun-Aug), and a biphasic pattern in progestagen activity was measured during gestation. Of additional interest, a preterm increase in estrogen that continued for an additional 64 days post partum. Male androgen activity correlated with the female estrogen patterns, with a single successful copulation occurring during the breeding season; interestingly however, the male exhibited no reproductive behaviors during the female's preterm/post partum estrogen increase. These data are the first reproductive steroid profiles for the peninsular pronghorn and provide valuable insight that will aid efforts that link the species' reproductive physiology with conservation management.