Premium
Reproductive seasonality in the female scimitar‐horned oryx ( Oryx dammah )
Author(s) -
Morrow C. J.,
Wildt D. E.,
Monfort S. L.
Publication year - 1999
Publication title -
animal conservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.111
H-Index - 85
eISSN - 1469-1795
pISSN - 1367-9430
DOI - 10.1111/j.1469-1795.1999.tb00072.x
Subject(s) - oryx , estrous cycle , biology , luteal phase , zoology , scimitar syndrome , sex ratio , medicine , endocrinology , ecology , population , hormone , lung , environmental health
Faecal oestrogen and progestin analyses were used to assess ovarian activity in non‐pregnant scimitar‐horned oryx ( Oryx dammah ) during a 13‐month interval. Mean (± SE) luteal phase, interluteal phase and oestrous cycle duration were 18.8 (± 0.5), 5.1 (± 0.2) and 23.8 (± 1.3) days, respectively. All females exhibited a synchronized anovulatory period that ranged from 36–95 days during spring. Short ovarian cycles (10.6 (± 0.8) days) were observed intermittently throughout the year and before the spontaneous resumption of oestrous cyclicity. Periovulatory peaks in oestrogen concentrations were detected for 42.5% (31/73) of ovarian cycles. A parallel analysis of reproductive data from the North American studbook (1985–1994) revealed that captive‐held scimitar‐horned oryx gave birth throughout the year. Sex ratio at birth was male‐biased (54.4%), and 19.1% of all calves failed to survive to 6 months of age (220 out of 1149 births). Only 0.7% of births resulted in twins. Median interbirth interval was 277 days, and 75% of these intervals were less than 332 days. Interbirth interval was extended (P < 0.05) if parturition occurred from January through May. In summary, the scimitar‐horned oryx is a seasonally polyoestrous species that experiences a distinct anovulatory period during spring in north‐east America.