Social dominance and breeding activity in Spanish ibex (Capra pyrenaica) maintained in captivity

Abstract

The relationship between ovulatory activity and social dominance was determined in 10 Spanish ibex females by recording their plasma progesterone and plasma cortisol levels. In a second experiment, the influence of dominance status on the establishment of pregnancy after introduction to males during late anoestrous (late October) was evaluated in another nine females. Dominance hierarchies were established in both groups by noting agonistic interactions between the individual females. Six high-ranking females of the 10 ibexes without male contact showed ovulatory activity with 1–3 progesterone cycles. The first progesterone cycle appeared in December (18 December ± 4 days). Dominance status correlated with age (R = 0.86, P < 0.01), bodyweight (R = 0.96, P < 0.001) and the number of progesterone cycles (R = 0.82, P < 0.01). Cortisol differences were associated with differences in reproductive function rather than social status per se. Introduction to males during late anoestrous brought forward the initiation of ovulatory activity (14 November ± 5 days) and resulted in three pregnancies in females with higher dominance ranks. The results suggest that social interactions are important in the control of ovulatory activity in the Spanish ibex.