Splitting Hairs: Shedding light on the diet of Kruger’s wild dogs

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This original article by Bruce Crossey originally appeared in Kruger Magazine Issue 20 (Winter 2022)

African wild dogs are South Africa’s most endangered carnivores. Now loved for their unique personalities, playful nature, and reliance on pack dynamics for social support, wild dogs have had a chequered past filled with persecution and human conflict. This is largely due to the way wild dogs kill and consume their prey. Unable to deliver a killing bite, and reliant on assistance from pack members to hunt species much larger than themselves, wild dogs disembowel their prey in a manner that can appear gruesome to anyone bearing witness to a successful hunt. Until recently, this has earned wild dogs the unfair label of “cruel killers”. We now know that this hunting strategy is utilised out of necessity, as wild dogs are particularly prone to having their kills stolen by other predators, such as spotted hyenas and lions in a phenomenon known as kleptoparasitism.

Following a period of anti-wild dog sentiment, understanding and empathy has helped to shift the court of public opinion in favour of the dogs, and painted wolves are now a “must-see” on everyone’s sightings wish list. The Kruger National Park remains the ultimate refuge for the species in South Africa, and is still the only conservation area able to house a genetically viable, self-sustaining, population of wild dogs. This makes understanding wild dog behaviour within the Kruger integral to conservation efforts, with information on pack hunting dynamics and dietary preferences laying the foundation for future research.

Wild dogs can maintain home ranges as large as 550 km2, making observing their feeding and hunting behaviour incredibly difficult. Previous research based on observational data has led researchers to believe that wild dogs favour impala and kudu across the Park. But could there be something that we are missing? Do wild dogs alter their prey preferences as the abundance of prey species shift, and competing predator numbers change? In order to answer these questions, we need to examine the diet of wild dogs even when we cannot observe them directly. But how? The answer comes in the form of Stable Isotope Analysis. These analyses push on the principle of “you are what you eat” to a whole new level. Broadly speaking, this methodology allows us to track the flow of different heavy to light ratios of Carbon and Nitrogen through systems, giving each species a unique isotopic signature based on their diet and metabolism. This allows us to reconstruct the dietary history of an animal using inert tissue samples, such as hair or whiskers, which hold information on the food sources consumed over the entire period during which the tissue was formed. Thus,  through a collaborative effort between the University of Pretoria’s Mammal Research Institute and Stable Light Isotope Laboratory, Endangered Wildlife Trust (EWT), SANParks and the Wild dog Advisory Group of South Africa (WAG-SA), we launched a project to reconstruct the dietary history of 73 wild dogs, across 40 packs that were sampled in different regions of central to southern Kruger between 2009 and 2018.

As previous research has suggested, our results show that impala encompass more than half of wild dog diet for packs sampled in the mixed woodlands around Afsaal, and then down from Orpen towards Skukuza. Markedly fewer impala are present in the Malelane mountain bushveld surrounding Berg-en-dal. Here, we see that wild dog packs are able to compensate by feeding on small browsing species (including bushbuck, steenbok and grey duiker) for approximately a third of their diet, with another quarter of their diet being made up of a combination of large grazers (zebra, buffalo, blue wildebeest, reedbuck and waterbuck).  Kruger wild dog diet is most variable along the thickets of the Sabie and Crocodile river. Here, impala make up a third of their diet, and large grazing species make up another quarter, but surprisingly almost half of their diet comprises small browsers. This is most likely because hunting in thickets allows wild dogs to make use of opportunistic and ambush hunting strategies, while the extra cover provided by the landscape also helps packs to avoid kleptoparasitism by spotted hyenas and lions. In stark contrast, wild dogs found in the lowveld sour bushveld between Pretoriuskop and Phabeni gate rely heavily on large grazers and kudu for up to almost 70% of their diet. The sour grasses in these areas are generally avoided by buffalo, resulting in a lower lion density, and wild dogs in this landscape type likely find it profitable to hunt larger prey species more regularly than smaller species, particularly if their pack size is large enough.

These results place a spotlight on how adaptable African wild dogs are in terms of their hunting preferences and techniques. In the context of the Kruger National Park, this provides valuable insight into how packs may respond to future fluctuations in predator and prey densities. This improved understanding of wild dog prey preferences draws attention to previously undescribed predator-prey dynamics that exist between wild dogs and their prey species at the localised habitat level. For example, we see that small browsing antelope are more prone to being hunted by wild dogs in the Malelane mountain bushveld, and Sabie and Crocodile river thickets, than previously thought. This lays the groundwork for future research to closely examine the dynamics that exist between these species, and investigate how prey populations may look to combat relatively high levels of predation by wild dogs in these areas. More broadly, determining prey requirements for wild dogs in different habitat types assists with the evaluation of potential new sites for wild dog reintroductions outside of the Kruger National Park.

Kruger, however, remains the mecca for African wild dogs in South Africa, and ongoing research to keep track of it’s wild dog population remains vital for monitoring the wellbeing of the species. Much like the dogs, I bid you happy hunting, and hope you are able to steal some special moments with these enigmatic icons of the African bush on your next trip to the Park.