Traditional prey preference models use a coarse species-specific prey body mass of three-quarters of adult female body mass, assumed to reflect the average mass across the prey population. This ignores demographic-specific prey preferences, potentially biasing estimates of preferred prey sizes. We refined prey selection models for two model predators with contrasting hunting strategies, by including seasonal consumption and availability of prey demographic classes. We predicted that cheetahs would select for smaller neonate and juvenile prey, while lions would select for larger, adult prey. We further predicted seasonal diet shifts in cheetah, but not lion. We recorded species and demographic class prey use via direct observation and GPS cluster of cheetahs and lions fitted with GPS collars. Species and demographic class prey availability was estimated from monthly driven transects. Seasonal availability of prey demographic classes resulted in predicted, contrasting prey preferences for cheetah and lion. Cheetahs preferred neonates, juveniles, and sub-adults during the wet season, but adults and juveniles during the dry season. Lions preferred adult prey irrespective of season, with sub-adults, juveniles, and neonates killed relative to their abundance. Thus traditional, prey preference models do not adequately account for demographic-specific prey preference. This masks the prey use and potential preferences for different demographic classes. This is particularly important for smaller predators, like cheetahs, whose prey selection focusses on smaller prey, particularly juveniles of larger species. For these smaller predators, prey availability will vary strongly seasonally, making them more vulnerable to processes that influence prey reproduction, like global change.
