Body mass relationships affect the age structure of predation across carnivore-ungulate systems: A review and synthesis
1. The size or body mass of predators relative to prey plays a key role in structur-ing animal communities, as the strength of predator–prey interactions is often dependent on the body mass relationship. Also, in long-lived species, a direct functional relationship exists between adult survival and population growth rate. Therefore, any cause of mortality acting on the adult segment of the population is expected to exert a strong influence on population performance. 2. Despite the large amount of literature available on carnivore–ungulate preda-tion patterns, the relationship of predator and prey body mass with the age structure of predation has not yet been synthesised within a common framework. We review the main studies conducted during the last five decades on carnivore– ungulate predation patterns, and synthesise how the body mass relationship influences the age composition of individuals killed. 3. For each study, we compiled the predator and prey species under study, their body mass and sex, the geographical location of the study site, the methodology used, and the resulting age composition of individuals killed, at the highest available resolution. We used generalised linear mixed effects models to assess the influence of all these variables on the proportion of individuals killed consisting of juveniles. 4. The proportion of individuals killed that were juvenile in a given predator– prey system was strongly dependent on prey body mass, with a positive asymptotic relationship. The asymptote value decreased for increasing predator body mass. Also, felids and canids followed different trajectories. Male predators killed more adults than female predators, and the proportion of juveniles in their diet was lower when predators were preying on solitary ungulates, than when they were preying on species living in groups or herds. 5. Morphological and behavioural traits of predator and prey species interact to influence the age structure of predation, with possible consequences on the potential for different carnivore species to affect their prey demography.