Trends in large carnivore diets in the Addo Elephant National Park, South Africa
- Authors: Wentworth, Julia Claire
- Date: 2013
- Subjects: Game reserves -- South Africa , Carnivorous animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10595 , http://hdl.handle.net/10948/d1020993
- Description: Determining carnivore diets and how they may change over time is important if the management of large carnivores is successful in an enclosed reserve. Carnivore diets are known to shift over time in response to a variety of factors. These factors include prey availability and climatic conditions (rainfall patterns). The re-introduction of lions (Panthera leo) and spotted hyaena (Crocuta crocuta) to Addo Elephant National Park (AENP), South Africa provided the opportunity to study diet trends of lions and spotted hyaena in an enclosed system. The study focused on the diets and overlap of lions and spotted hyaena and how their prey selection changed since their re-introduction in 2003 to 2010. The database included scats collected over a seven year period. A total of 195 spotted hyaena scats and 217 lion scats were analysed using scat analysis. Prey items estimated from scat samples were coupled with prey availabilities to determine preferred prey items. Additionally, from determined carnivore diets, lions and spotted hyaena diet overlap was estimated over time. Lions preferred prey items which included zebra (Equus quagga) and eland (Tragelaphus oryx) during the early portion of the study. Over time preference shifted to include buffalo (Syncerus caffer), bushbuck (Tragelaphus scriptus) and grey duiker (Sylvicapra grimmia). Spotted hyaena preferred zebra and eland in the earlier part of the study, then over time, shifting their selection to grey duiker, buffalo, red hartebeest (Alcephalus busephalus) and bushbuck. Lions and spotted hyaena had a similar diet which increased in overlap during the study (67 percentage - 91 percentage). Our findings suggest that lions and spotted hyaena had a degree of diet specialization; both carnivores avoided and preferred certain prey items relative to their abundance. Their preference excluded the most abundant prey items, thus causing a decline in abundance of rarer species over time. Lions and spotted hyaena did not respond by shifting their diets to consume abundant prey items when their preferred prey items declined in availability. However, this study may be a snap-shot of carnivore’s diet trends. Thus further monitoring of the large carnivore diets should be researched in order to determine which factors drive their prey selection. Additionally, lions and spotted hyaena diet overlap increased overtime. The high diet overlap may be a result from spotted hyaena scavenging off lion kills, thus spotted hyaena diets may be facilitated by lion kills. Finally our data suggests that re-introduced large carnivores in AENP are likely to change the composition of the overall mammal community, potentially eliminating rare but preferred prey species in an enclosed reserve.
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- Date Issued: 2013
Incorporating prey demographics and predator social structure into prey selection and carrying capacity estimates for cheetah
- Authors: Clements, Hayley Susan
- Date: 2012
- Subjects: Carnivorous animals , Cheetah
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10754 , http://hdl.handle.net/10948/d1018606
- Description: There is a need for a refined understanding of large carnivore prey preference and carrying capacity (K). To date, K estimates for large carnivores have been developed from predictions of carnivore diet at a prey and predator species-level. These predictions therefore assume that all social classes within a carnivore species display similar prey preferences and that all demographic classes within a prey species are equally preferred or avoided. The objective of this study was to investigate the importance of including prey demographics and carnivore social class in carnivore diet descriptions and thereby K estimates, using cheetah Acinonyx jubatus as a study species. It was predicted that prey sex, prey age and cheetah social class influence cheetah prey preferences, when they influence the risk and ease of prey capture, and that their inclusion in a K model would improve its predictive strength. Based on an analysis of 1290 kills from South Africa, male coalition cheetah were found to prefer a broader weight range of prey than solitary cheetah. Prey demographics further influenced cheetah prey preference, when it corresponded to differences in prey size and the presence of horns. The current species-level K regression model for cheetah is based on preferred prey and thus omits highly abundant antelope that often comprise the majority of the diet, an artefact of the way in which preferences are calculated. A refinement of the species-level K regression model, to account for prey demographic- and cheetah social class-level differences in diet and the biomass of accessible prey (defined in this study as all non-avoided prey) instead of just preferred prey, doubled the predictive strength of the K model. Because group-hunting enabled predation on a broader weight range of prey, cheetah K was influenced by the ratio of male coalition cheetah to solitary cheetah in the population. The refined K regression model is derived from ecosystems supporting an intact carnivore guild. A mechanistic approach to estimating K, based on Caughley‟s (1977) maximum sustainable yield model, therefore better predicted cheetah K in systems devoid of lion Panthera leo and African wild dog Lycaon pictus, which were found to suppress cheetah density. This study improves our understanding of the relationships between prey demographics, cheetah social classes and intra-guild competition in determining cheetah prey preferences and K. This study therefore paves the way for similar work on other large carnivores.
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- Date Issued: 2012