Can smaller predators expand their prey base through killing juveniles? The influence of prey demography and season on prey selection for cheetahs and lions

Abstract

Smaller predators may overcome body size restrictions on their prey base by selecting for juveniles of larger prey species. However, traditional prey selection models ignore demographic classes within prey species. We refined these models for two predators with contrasting body sizes and hunting strategies, by including seasonal consumption and availability of prey demographic classes. We predicted that cheetahs would select for smaller neonate and juvenile prey especially of larger species, while lions would select for larger, adult prey. We further predicted seasonal diet shifts in cheetah, but not lion. We recorded species-specific demographic class prey use (kills) via direct observation and GPS cluster of cheetahs and lions fitted with GPS collars. Species-specific demographic class prey availability was estimated from monthly driven transects, and species-specific demographic class prey preferences were estimated. The availability of prey demographic classes varied seasonally. 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. This confirms that traditional prey preference models do not adequately account for demographic-specific prey preference. This is particularly important for smaller predators, like cheetahs, that focus on smaller prey but can expand their prey base by killing 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.

Keywords: Cheetah; Demographic-specific predation; Lion; Prey preference; Seasonal diet.

Fig. 1

Crude accessible prey mass ranges (horizontal bars) of lion and cheetah plotted across demographic class and standardized masses (vertical lines) of the plains zebra (extracted from Clements et al. ; Kingdon et al. 2013)

Fig. 2

Lapalala Wilderness Reserve showing the eight transects (dotted lines) driven during the monthly prey transects in area A. A Southern section of Lapalala with predator and prey species. B Northern section of Lapalala with no predators. There is a wildlife-proof fence that separates the northern and southern sections, and the northern section was not used in the present study

Fig. 3

Relative abundance (± SE) of herbivores (pooled across seasons) on Lapalala Wilderness Reserve during 2019–2020

Fig. 4

Relative abundance (± SE) of demographic classes of the three most abundant prey species–impala, blue wildebeest, and plains zebra—on Lapalala Wilderness Reserve, during the a dry and b wet seasons of 2019–2020

Fig. 5

Percentage contribution of prey species, pooled across seasons, to a cheetah and c lion diet and the demographic composition of prey killed by b cheetah and d lion on Lapalala Wilderness Reserve in 2019–2020

Fig. 6

Segmented relationship of cheetah (a and c) and lion (b and d) prey preference and the prey mass rank during the dry (orange) and wet (blue) seasons. The seasonally available body mass range (horizontal lines), divided into demographic classes (neonate: mass (kg) from 0 to 3 months old; juvenile: mass from 3 to 12 months old; sub-adult: mass from 12 months to age of sexual maturity; adult: mass from age of sexual maturity), of consumed prey are provided for reference