Foraging investment in a long‐lived herbivore and vulnerability to coursing and stalking predators

Abstract

Allocating resources to growth and reproduction requires grazers to invest time in foraging, but foraging promotes dental senescence and constrains expression of proactive antipredator behaviors such as vigilance. We explored the relationship between carnivore prey selection and prey foraging effort using incisors collected from the kills of coursing and stalking carnivores. We predicted that prey investing less effort in foraging would be killed more frequently by coursers, predators that often exploit physical deficiencies. However, such prey could expect delayed dental senescence. We predicted that individuals investing more effort in foraging would be killed more frequently by stalkers, predators that often exploit behavioral vulnerabilities. Further these prey could expect earlier dental senescence. We tested these predictions by comparing variation in age‐corrected tooth wear, a proxy of cumulative foraging effort, in adult (3.4–11.9 years) wildebeest killed by coursing and stalking carnivores. Predator type was a strong predictor of age‐corrected tooth wear within each gender. We found greater foraging effort and earlier expected dental senescence, equivalent to 2.6 additional years of foraging, in female wildebeest killed by stalkers than in females killed by coursers. However, male wildebeest showed the opposite pattern with the equivalent of 2.4 years of additional tooth wear in males killed by coursers as compared to those killed by stalkers. Sex‐specific variation in the effects of foraging effort on vulnerability was unexpected and suggests that behavioral and physical aspects of vulnerability may not be subject to the same selective pressures across genders in multipredator landscapes.

Predation strongly limits demography of a keystone migratory herbivore in a recovering transfrontier ecosystem

“…Immobilized wildebeest were monitored for temperature and respiration and fitted with collars while blood, tissue, hair, and fecal samples were obtained from each animal. Measurements of shoulder height and body length were performed, as well as measurements of tooth wear on the I1 and I2 incisor teeth to estimate age (Christianson et al, 2018 ). When possible, the animal was physically checked for pregnancy.…”

The possible role of predator–prey dynamics as an influence on early hominin use of burned landscapes

“…Although intergroup dynamics can make vigilance a tricky measure in primates, larger aggregations can sometimes act as a deterrent to certain types of predators specifically those that rely on surprise attack . However, larger groups can be more conspicuous to coursing predators (endurance predators who can pursue prey over long distances) especially pack hunters who are rarely deterred by the group size of prey animals and instead select individuals to attack once flight ensues . Larger group sizes can also negatively impact individual within‐patch return rates, depending on patch size, by decreasing marginal returns and forcing individuals to leave a patch earlier in search of another …”

“…Palaeoecological data concerning habitat selection, hunting tactics and prey selection of the African carnivore guild have been proposed by several researchers and show all the above to be varied . Regarding habitat selection and across the Plio‐Pleistocene large predators such as Acinonyx , Chasmaporthetes , Crocuta, Homotherium, Machairodus, Lycaon and Panthera leo all show preference toward open habitats, while Hyaena, Parahyaena , Pliocrocuta, Pachycrocuta and Panthera pardus are generalists, and Agriotherium, Dinofelis and Megantereon show preference toward more woodland cover.…”

“…41 However, larger groups can be more conspicuous to coursing predators (endurance predators who can pursue prey over long distances) especially pack hunters who are rarely deterred by the group size of prey animals and instead select individuals to attack once flight ensues. 46 Larger group sizes can also negatively impact individual within-patch return rates, depending on patch size, by decreasing marginal returns and forcing individuals to leave a patch earlier in search of another. 18,19,24,26 However, optimal foraging models rarely account for how spatial variation in predation risk may impact foraging decisions for prey animals at risk from multiple predators with different hunting and attack modes.…”

“…[8][9][10]52 Palaeoecological data concerning habitat selection, hunting tactics and prey selection of the African carnivore guild have been proposed by several researchers and show all the above to be varied. [45][46][47][49][50][51] Regarding habitat selection and across the Plio-Pleistocene large predators such as Acinonyx, Chasmaporthetes, Crocuta, Homotherium, the pack hunters likely having the ability to taking larger prey, while the smaller bodied solitary hunters preferred smaller prey. 53,54 According to Treves and Palmqvist, 49 Both the canids and hyenas are suggested to have posed sporadic threats to hominins (the latter mainly around competition for carcasses) while Dinofelis is suggested to have posed a more significant threat.…”