Does the presence of large predators affect the diet of a mesopredator?

Abstract

The mesopredator release hypothesis states that when middle-ranked predators are freed from the top-down control of apex predators, their populations will increase and predation pressure on certain prey species intensifies (Prugh et al., 2009). Examples include the release of coyotes (Canis latrans, Say 1823) following the extirpation of wolves (Canis lupus, L. 1758) in Wyoming, USA (Berger & Conner, 2008) and the suppressing effect of dingoes (Canis lupus dingo, Meyer 1793) on red fox (Vulpes vulpes, L. 1758) populations in eastern Australia (Johnson & Vanderwal, 2009). The hypothesis may provide a theoretical framework to explain the overall success of black-backed jackals (Canis mesomelas, Schreber 1775) in South Africa (Loveridge & Nel, 2004), following the extirpation of large (apex) predators, such as lions (Panthera leo, L. 1758), from many parts of their range, in the early twentieth century (Crooks & Soule, 1999). However, the increased potential for earning foreign income from trophy hunting and ⁄ or ecotourism has seen a significant change in the land use of the Eastern Cape of South Africa (Smith & Wilson, 2002). Many agrarian properties have been converted into game farms and wildlife reserves (Smith & Wilson, 2002), and large predators have been reintroduced to attract tourists (Hayward et al., 2007). The reintroduction of superior predators to game reserves may therefore reinstate top-down forcing in these systems (Estes et al., 2011), resulting in mesopredator suppression effects, such as spatial avoidance and behavioural suppression via altered activity patterns and dietary avoidance (Hayward & Kerley, 2008; Hayward & Slotow, 2009; Van Der Merwe et al., 2009). The objective of this study was to compare the dietary composition of two black-backed jackal populations; one with large predators present and one without.