Journal Article

Predator-prey size relationships in an African large-mammal food web

Owen-Smith, Norman, Mills, M.G.L

2008

Overview

1. Size relationships are central in structuring trophic linkages within food webs, leading to suggestions that the dietary niche of smaller carnivores is nested within that of larger species. However, past analyses have not taken into account the differing selection shown by carnivores for specific size ranges of prey, nor the extent to which the greater carcass mass of larger prey outweighs the greater numerical representation of smaller prey species in the predator diet. Furthermore, the top-down impact that predation has on prey abundance cannot be assessed simply in terms of the number of predator species involved. 2. Records of found carcasses and cause of death assembled over 46 years in the Kruger National Park, South Africa, corrected for under-recording of smaller species, enabled a definitive assessment of size relationships between large mammalian carnivores and their ungulate prey. Five carnivore species were considered, including lion (Panthera leo), leopard (Panthera pardus), cheetah (Acinonyx jubatus), African wild dog (Lycaon pictus) and spotted hyena (Crocuta crocuta), and 22 herbivore prey species larger than 10 kg in adult body mass. 3. These carnivores selectively favoured prey species approximately half to twice their mass, within a total prey size range from an order of magnitude below to an order of magnitude above the body mass of the predator. The three smallest carnivores, i.e. leopard, cheetah and wild dog, showed high similarity in prey species favoured. Despite overlap in prey size range, each carnivore showed a distinct dietary preference. 4. Almost all mortality was through the agency of a predator for ungulate species up to the size of a giraffe (800-1200 kg). Ungulates larger than twice the mass of the predator contributed substantially to the dietary intake of lions, despite the low proportional mortality inflicted by predation on these species. Only for megaherbivores substantially exceeding 1000 kg in adult body mass did predation become a negligible cause of mortality. 5. Hence, the relative size of predators and prey had a pervasive structuring influence on biomass fluxes within this large-mammal food web. Nevertheless, the large carnivore assemblage was dominated overwhelmingly by the largest predator, which contributed the major share of animals killed across a wide size range.

• Publisher: Oxford, UK : Blackwell Publishing Ltd,British Ecological Society,Blackwell Publishing Ltd,Blackwell
• Subject: Acinonyx jubatus / adults / Animal and plant ecology / Animal physiology / Animal, plant and microbial ecology / Animals / Biological and medical sciences / Biomass / Body Size / Body Size - physiology / Body Weight / Body Weight - physiology / Carnivora / Carnivora - physiology / Carnivores / Cheetahs / Crocuta crocuta / death / Diet / dietary niche / Dogs / Ecology / Ecosystem / Feeding Behavior / Feeding Behavior - physiology / Female / Food Chain / Food chains / food intake / Food webs / Fundamental and applied biological sciences. Psychology / General aspects / Herbivores / Hyenas / Kruger Park / lion / Lions / Lycaon pictus / Male / Mammalia / Mammals / Mortality / National parks / Panthera leo / Panthera pardus / Perissodactyla / Perissodactyla - physiology / physiology / Population Dynamics / Predation / predation pressure / Predators / Predatory Behavior / Predatory Behavior - physiology / Prey / prey preferences / Size / South Africa / Trophic Interactions / Ungulates / Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution / Wildlife ecology