I’ve been away for fieldwork for much of the last two months, but have managed to get a new post ready. Today’s post looks at the wild dog population in Kruger National Park – how they’re affected by pack size, and the distribution of prey and competitors. There’s three studies that I’ll draw information on for this – one is fairly old (1997) and was conducted in the southern part of Kruger National Park, and the other two are more recent (2010 and 2012) and from the Okavango Fan in Botswana.
Mills and Gorman (1997) tracked wild dog packs in southern Kruger, by following one or two individuals in the pack who were radio-collared. From this, they were able to figure out how packs moved in relation to other packs, and also how they move through different habitats. The researchers also surveyed herbivore (prey species) populations in the different habitats, estimated from aerial photos, and competing predators (lions and hyenas), whose concentrations were estimated in specific areas by checking how many of them were attracted to a tape recording per hour. Most large predator species have a distribution, as you would guess, that mirrors the distribution of their prey, because this means it’s easier for them to hunt and eat. For wild dogs though, Mills and Gorman surprisingly showed that they had lower concentrations in areas where their favourite prey (impala and kudu) were more abundant. This is because the habitats of wild dogs’ preferred prey species coincided with high lion concentrations, and it’s more important for wild dogs to avoid competitors than it is for them to live in areas with a lot of their own prey. Lions, particularly, kill a significant percentage of both young and adult wild dogs – so it seems the dogs have to take every effort to avoid lions.
The relations between lions, wild dogs and hyenas were investigated further in two studies by Webster et al. (2010, 2011), who worked in the Okavango Fan and tested how wild dogs, hyenas and lions reacted to hearing tape recordings of each other’s sounds. Wild dogs fled rapidly from lion sounds, and lions actively sought out wild dogs when hearing their sounds. Hyenas did not react as strongly to wild dog sounds as lions did, and wild dogs, equally, were not as disturbed by hyenas.
The observations of wild dog behaviour described above show that wild dogs have to go to great lengths to reduce or avoid direct competition with lions. By contrast, hyenas are less of a threat, or else simply impossible for wild dogs to avoid. This goes some way to explaining why wild dogs have much lower concentrations in suitable habitats than either lions or hyenas do.
Mills, M.G.L., and Gorman, M.L. 1997. Factors affecting the density and distribution of wild dogs in the Kruger National Park. Conservation Biology vol. 11, page 1397-1406.
Webster, H., McNutt, J.W., and McComb, K. 2010. Eavesdropping and risk assessment between lions, spotted hyenas and African wild dogs. Ethology vol. 116, page 233-239.
Webster, H., McNutt, J.W., and McComb, K. 2011. African wild dogs as a fugitive species: playback experiments investigate how wild dogs respond to their major competitors. Ethology vol. 117 page 1-10.