Female reproductive success in captive Ammotragus lervia (Bovidae, Artiodactyla). Study of its components and effects of hierarchy and inbreeding

Four components of female reproductive success in captive Saharan arrui (Barbary sheep), Ammotragus lervia sahariensis (Rothschild, 1913), have been analysed: longevity, fecundity, offspring one-month survival rate and the age of first birth. Longevity accounts for 69.9% of the variance of reproductive success, fecundity for 54.2%, offspring one-month survival rate for 29.8%, and the age at first birth for 10.4%. A detailed study of these components leads to the following conclusions: (a) longevity is higher in those individuals in better physical condition; (b) fecundity is related to age and social rank; (c) heavier offspring at birth have a higher probability of surviving during their first month of life; and (d) the age at first birth is delayed by high levels of population density, inbreeding coefficients, and birth weights. On the other hand, high-ranking females are characterized by shorter inter-birth intervals and give birth to a higher proportion of twins.