 Females reach sexual maturity between one @-@ and @-@ a @-@ half to three years of age . They typically average one litter every two to three years throughout their reproductive lives , though the period can be as short as one year . Females are in estrus for about 8 days of a 23 @-@ day cycle ; the gestation period is approximately 91 days . Females are sometimes reported as monogamous , but this is uncertain and polygyny may be more common . Copulation is brief but frequent . Chronic stress can result in low reproductive rates when in captivity as well as in the field . 
 Females reach sexual maturity between one @-@ and @-@ a @-@ half to three years of age . They typically average one litter every two to three years throughout their reproductive lives , though the period can be as short as one year . Females are in estrus for about 8 days of a 23 @-@ day cycle ; the gestation period is approximately 91 days . Females are sometimes reported as monogamous , but this <a href='drop_aux' title='1'><mark>is</mark></a>uncertain and polygyny may be more common . Copulation <a href='drop_aux' title='2'><mark>is</mark></a>brief but frequent . Chronic stress can result in low reproductive rates when in captivity as well as in the field . 
Females reach sexual maturity between one @-@ and @-@ a @-@ half to three years of age . They typically average one litter every 2 to three years throughout their reproductive lives , doe the period can b as short as one year . Females are in estrus for about 8 days of a 23 @-@ day cycle ; the gestation period is approximately 91 dayz . Females are sometimes reported as monogamous , but this uncertain and polygyny may bbmore common . Copulation brief but frequent . Chronic stress can result in low reproductive rates when in captivity as well as in da field .