Patterns of mouflon (Ovis gmelini) survival under moderate environmental conditions: effects of sex, age, and epizootics

Abstract

We estimated survival probabilities over a 9-year period for an introduced population of Mediterranean mouflon (Ovis gmelini), applying capture – recapture models to resighting data from individually marked animals. Survival was high and constant among lambs, yearling males, and adults of both sexes, and we were unable to detect senescence among old animals. Survival of female yearlings varied widely among years. No difference in survival probabilities between the sexes was detected, indicating that the survival costs of sexual selection were low in this dimorphic species. We suggest that these results may be explained by a lack of limiting conditions on this study site. An outbreak of keratoconjunctivitis during the rut of 1993 caused a marked fall in annual survival for both sexes. Among males, this decline was constant for all ages (approximately 23%), but for females the impact of the disease varied in relation to age, with young ewes particularly affected. Otherwise, the population appears to be stable and we hypothesise that the removal of animals for export and through hunting, together with stochastic events such as periodic epizootics, maintains mouflon numbers at a level where the influence of density-dependent resource limitation on survival is limited.