Interspecific and geographic variation in the diets of sympatric carnivores: dingoes/wild dogs and red foxes in south-eastern Australia.

David M. Forsyth,Joe Benshemesh,Alan Robley,Dale G. Nimmo,Lindy F. Lumsden,Jenny Lawrence,Charlie Pascoe,Barbara Triggs,Naomi E. Davis,Euan G. Ritchie,Mathew S. Crowther

doi:10.1371/journal.pone.0120975

Abstract

Dingoes/wild dogs (Canis dingo/familiaris) and red foxes (Vulpes vulpes) are widespread carnivores in southern Australia and are controlled to reduce predation on domestic livestock and native fauna. We used the occurrence of food items in 5875 dingo/wild dog scats and 11,569 fox scats to evaluate interspecific and geographic differences in the diets of these species within nine regions of Victoria, south-eastern Australia. The nine regions encompass a wide variety of ecosystems. Diet overlap between dingoes/wild dogs and foxes varied among regions, from low to near complete overlap. The diet of foxes was broader than dingoes/wild dogs in all but three regions, with the former usually containing more insects, reptiles and plant material. By contrast, dingoes/wild dogs more regularly consumed larger mammals, supporting the hypothesis that niche partitioning occurs on the basis of mammalian prey size. The key mammalian food items for dingoes/wild dogs across all regions were black wallaby (Wallabia bicolor), brushtail possum species (Trichosurus spp.), common wombat (Vombatus ursinus), sambar deer (Rusa unicolor), cattle (Bos taurus) and European rabbit (Oryctolagus cuniculus). The key mammalian food items for foxes across all regions were European rabbit, sheep (Ovis aries) and house mouse (Mus musculus). Foxes consumed 6.1 times the number of individuals of threatened Critical Weight Range native mammal species than did dingoes/wild dogs. The occurrence of intraguild predation was asymmetrical; dingoes/wild dogs consumed greater biomass of the smaller fox. The substantial geographic variation in diet indicates that dingoes/wild dogs and foxes alter their diet in accordance with changing food availability. We provide checklists of taxa recorded in the diets of dingoes/wild dogs and foxes as a resource for managers and researchers wishing to understand the potential impacts of policy and management decisions on dingoes/wild dogs, foxes and the food resources they interact with.

Highlights

Large- and medium-sized mammalian carnivores influence ecosystem structure and function worldwide through predation and intraguild competition [1, 2]
Our study revealed substantial overlap in the diets of the larger-bodied wild dog and the smaller-bodied red fox in Victoria
The diet of foxes consisted of less mammals and more reptiles, insects and plant material

Summary

Introduction

Large- and medium-sized mammalian carnivores influence ecosystem structure and function worldwide through predation and intraguild competition [1, 2]. Mammalian carnivore species often co-occur, potentially creating complex interspecific interactions and trophic dynamics. If sympatric carnivores use the same food resources, interactions can range from commensalism to mutualism to competition and predation [11,12,13,14,15]. The relative size of co-occurring carnivores contributes to these interactions. Interspecific killing within carnivore guilds, which contributes to different mortality rates across carnivore species, is related to body size [20], and may be symmetrical (both species kill each other) or asymmetrical (one species kills the other) [21]. Carrion can form an important component of the diet of carnivores, which may scavenge on the carcasses of animals much larger than themselves [22, 23]

Methods

Results

Conclusion