Sexual conflict in red deer: male-male competition can delay the reproductive phenology of younger females

Investigating factors related to reproductive phenology is of particular interest in mammals with long gestation times, as the optimal adjustment of the timing of births depends on factors that occur much earlier. In Mediterranean environments, delays in conception timing in red deer populations, mainly due to climatic and demographic factors, lead to a mismatch between resource availability and the energy needs of hinds and offspring. In this polygynous species, the sex and age structure of populations determines the level of intrasexual competition, and the mating attempts of males may affect the behaviour and spatial distribution of females. In this paper, we used data from 14 years of females harvested in hunting actions in several estates with different population structures and, therefore, different levels of mate competition between males. The main aim was to explore the factors underlying variation in mating dates considering individual female and population characteristics. We found that the age and body condition of females are the main variables determining the mating date. However, our results showed a greater asynchrony in populations where mate competition is intense. Younger females suffer a delay in the mating date where intrasexual competition between males is high. These results point to a situation of conflict between the sexes, in which the behaviour of males to maximise their mating success may entail costs for the reproduction of females, which in turn is an example of the negative effects of a component of sexual selection on population dynamics.