Estimating carnivoran diets using a combination of carcass observations and scats from GPS clusters

Abstract

Scat analysis is one of the most frequently used methods to assess carnivoran diets and Global Positioning System (GPS) cluster methods are increasingly being used to locate feeding sites for large carnivorans. However, both methods have inherent biases that limit their use. GPS methods to locate kill sites are biased towards large carcasses, while scat analysis over-estimates the biomass consumed from smaller prey. We combined carcass observations and scats collected along known movement routes, assessed using GPS data from four African lion (Panthera leo) prides in the Kruger National Park, South Africa, to determine how a combination of these two datasets change diet estimates. As expected, using carcasses alone under-estimated the number of feeding events on small species, primarily impala (Aepyceros melampus) and warthog (Phacochoerus africanus), in our case by more than 50% and thus significantly under-estimated the biomass consumed per pride per day in comparison to when the diet was assessed using carcass observations alone. We show that an approach that supplements carcass observations with scats that enables the identification of potentially missed feeding events increases the estimates of food intake rates for large carnivorans, with possible ramifications for predator-prey interaction studies dealing with biomass intake rate.

Seasonal Diet and Prey Preference of the African Lion in a Waterhole-Driven Semi-Arid Savanna

“…During the study period, adult male and female lions were sighted together in only 7% of the sightings (n = 1710). This is consistent with findings from Kruger National Park where GPS data from male and female lions suggest that males were only present with females at 10% of their kills [4]. Indeed, it has become apparent in Southern Africa that male lions hunt successfully and quite often in the absence of female lions [25], [26].…”

“…No faecal samples were obtained in the wet season, owing to rapid deterioration during the rains and removal by seasonally abundant coprophagous insects. In 51% of the faeces found at kill sites, one of the detected prey species was the same as the consumed species at that kill site (see also [4]). Samples were washed, sieved and sun dried to remove organic matter, and spread in a grid sampling tray.…”

“…Positional data were recorded hourly during the night and retrieved at regular intervals. We systematically searched for potential lion kill sites by identifying clusters of x:y location coordinates including ≥4 hours of sequential locations within a defined proximity (150 m), and these were then investigated on foot (see also [4], [24]). Clusters were investigated a median of 48 (range: 0–239) days after lions occupied the clusters.…”

“…Recent advances in GPS technology has allowed non invasive carcass observations and faecal analysis to gain increasing knowledge on large mammalian carnivores diet [3], [4], and has also permitted to study the spatial distribution of kills providing important information for predator-prey relationships [5]. Across-ecosystems, comparisons of large mammalian carnivore diet have now provided a good understanding of the preferred prey weight range of several carnivore species [6]–[8], but local studies are still needed to unravel the role of environmental factors and prey availability.…”

“…feeding locations) of African lions ( Panthera leo ) in Hwange National Park, Zimbabwe, a semi-arid African savanna structured by artificial waterholes, where there is a strong seasonal variation in both surface-water availability and forage quality [22]. We assessed lion diet by combining carcass observations and faeces collection from GPS clusters, a method with recognized strengths [3], [4]. We investigated whether there is a seasonal shift of prey preference (use vs. availability) suggestive of different foraging strategies in different seasons.…”