Effect of prey mass and selection on predator carrying capacity estimates

Abstract

The ability to determine the prey-specific biomass intake of large predators is fundamental to their conservation. In the absence of actual prey data, researchers generally use a "unit mass" method (estimated as 3/4 adult female mass) to calculate the biomass intake of predators. However, differences in prey preference and range across geographic regions are likely to have an influence on biomass calculations. Here we investigate the influence of estimated prey mass on leopard biomass calculations, and subsequently carrying capacity estimates, in an understudied mountain population.Potential leopard feeding sites were identified using global positioning system (GPS) location clusters obtained from GPS collars. We investigated 200 potential leopard feeding sites, of which 96 where actual feeding sites. Jaw bones, horns, hooves, and other indicative bones were used to determine gender and age of prey items, which were subsequently used to calculate mass of each prey item based on previously published values. There were significant differences in the biomass values calculated using the traditional unit mass method and the calculated prey masses obtained from leopard feeding sites. However, there were no considerable differences in the carrying capacity estimates using the preferred prey species model and leopard density estimates calculated using a nonbiased spatial approach, which suggests that estimating carnivore carrying capacity based on 3/4 adult female masses is a reliable method, also for the mountain population in this study.

Prey Preferences of the Jaguar Panthera onca Reflect the Post-Pleistocene Demise of Large Prey

“…Strongly supported relationships among individual variables were plotted using linear or loess best fit models. We estimated prey species body size as three-quarters of adult female body mass to account for juveniles and sub-adult prey killed (Jooste et al, 2013). Body mass, herd size, habitat use, and potential threat data were taken from Nowak (1999).…”

Niche overlap and dietary resource partitioning in an African large carnivore guild

“…However, the biomass of the preferred prey body mass range has been suggested to be a better predictor of cheetah density (Hayward et al, 2007). The biomass of prey (kg/km 2 ) was estimated using the unit mass of a prey species (adult female prey mass multiplied by a factor of 0.75, following Jooste et al (2013). This factor allows for the estimation of prey biomass by accounting for variance in prey sex or age categories.…”

The role of sleeping sites in the predator‐prey dynamics of leopards and olive baboons

“…A meta‐analysis found that leopards eat baboons significantly less often than expected based on prey abundance (Hayward et al, ), although at some times in some places leopard predation may be intense. For example, in the Waterberg Mountains of South Africa, baboons constituted over 20% of identified prey in the diet of three female leopards (Jooste, Pitman, van Hoven, & Swanepoel, ; Jooste, Hayward, Pitman, & Swanepoel, ). Leopards are solitary hunters that inhabit many types of environments in Africa and Asia, resulting in widely varying activity patterns and prey spectra (Hunter et al, ).…”