Reproductive biology and life history traits of Arabian oryx (Oryx leucoryx) founder females reintroduced to Mahazat as-Sayd, Saudi Arabia

Reproductive and life history data of Arabian oryx founder females reintroduced into Mahazat as-Sayd Protected Area in Saudi Arabia were collected from 1990 to 2007. A General Linear Model revealed a significant effect of both age and reproductive experience prior to release on overall and male birth rates. We also found an effect on the overall birth rate explained by age alone. Our data are in line with theories suggesting that females reaching a stage in their life where they are unlikely to raise further off-spring increase their investment into progeny and skew sex ratio of their off-spring towards males. Inter-calf interval corresponds with findings from reintroductions in Oman and elsewhere in Saudi Arabia but increased with progressing age. Calving occurred throughout the year with no distinct seasonality. Fecundity was higher in experienced founder females, albeit not significantly. Overall fecundity was highest in young females, decreased in middle aged animals, and remained stable throughout the rest of their life span. Our findings may have an influence on future reintroductions of Arabian oryx and confirm theories in behavioural ecology of ungulates.