Young and mature males have similar energy expenditure during the rut in a trophy-hunted population of Mediterranean mouflon

Abstract

In polygynous ungulates, males invest time and energy to reproductive activities during the rut and this involvement is expected to increase with age due to different mating tactics in young versus adult males. In contrast, mating period is expected to be less costly for females for which late gestation and lactation are the most energetically demanding periods. However, empirical supports of these hypotheses through direct measures of reproductive effort are still limited in ungulate species, particularly in males. In addition, this general pattern may be modified in populations facing selective harvesting on adult males, where young males may experience less competition to mate and invest more energy during the rut. We investigated these hypotheses by studying the age- and sex-specific variations of kidney fat reserves from pre- to post-rut periods in a trophy-hunted population of Mediterranean mouflon (Ovis gmelini musimon × Ovis sp.), a polygynous dimorphic mountain ungulate. Females were found to build up energy from the pre-rut to the post-rut periods, most likely to face with the subsequent costs of gestation/lactation that occur few months later. Conversely, kidney fat mass strongly decreased similarly in both young and mature males, and with the same magnitude, suggesting a strong investment of males of all ages in this population. This might be related to the selective hunting pressure on mature males this population is facing with. This result supports the need for more empirical and comparative studies to better grasp the influence of trophy hunting on reproductive effort in male ungulates.