Competition, Kleptoparasitism, and Hunting Group Size

            According to Carbone, Du Toit, and Gordon (1997), the Wild dog population has nearly vanished from the Serengeti plains. During the same period in the Serengeti, the hyena population has more than doubled, which is thought to be due to a substantial increase in the wildebeest and gazelle populations. The shift in population density of these two species has resulted in a significant increase in the ratio of hyenas to wild dogs in the Serengeti. Given that wild dogs are substantially smaller than hyenas, they can be driven off fresh kills by relatively few hyenas. This has been documented in a number of studies (see Eaton 1979; Fanshawe & Fitz Gibbon, 1993; Creel & Creel, 1996) which found a negative relationship between wild dog and hyena densities across six ecosystems.

            A simple model was developed to explore how variation in wild dog hunting group size in the Serengeti influences defense of kills against hyenas, and the trade-off effects this has on intake rate per dog for a given prey size. The article's primary focus is upon the question of whether increased access time at a kill (afforded by group defense against hyenas) compensates for the reduction in each dog's potential share of the carcass and, hence, whether adjustment of hunting group size is a strategy that wild dogs can employ against kleptoparasitism. Of secondary interest is the articles examination of the impact of kleptoparasitism on average profitability of different prey with varying hunting group sizes.

            The authors found that while kleptoparasitism substantially influences the amount of time a hunting group can access a kill, increases in access time with increased hunting group size rarely fully compensate for the reduction in each dog's share of the carcass due to ‘scramble competition’ among the dogs. This was displayed in a profitability index, which included limitations of the probability of capturing different sized prey, gut capacity, food depletion and access time, suggesting that the smaller the hunting group the more vulnerable it is to kleptoparasitism. Where hunting groups  of 1-2 would be particularly vulnerable because they are unable to fully satiate themselves before spotted hyenas take over their kills. Notably, intermediate-sized hunting groups may be most effective at meeting nutritional demands over a range of prey sizes.

Works Cited

Carbone, C., Du Toit, J. T. & Gordan, I. J. (1997). Feeding success in african wild dogs: Does      

kleptoparasitism by spotted hyenas influence hunting group size? Journal of Ecology (66), 318-326.

Welcome Back Video

ARKive - African wild dog video - Lycaon pictus - 15a

This is a video of what I believe to be one African wild dog being reintroduced to the pack after a tracking collar was placed on him/her.  This is the pack's reaction to the foreign object.

That's mine! Territorial Behavior in African Wild Dogs

African wild dogs are found in sub-Saharan Africa, which includes desert environments, flooded grasslands, tropical forests, and tropical grasslands. It is believed that wild dogs once lived throughout Africa, but their habitat size has shrunk to a few countries: Zambia, Zimbabwe, Namibia, Botswana, and Angola. The reduction in habitat has restricted many wild dogs to National reservations and parks. 

A territory for a pack can range anywhere in size from 650 to 900 square miles. Territories need to be large enough to support all of the pack members. African wild dogs tend to be crepuscular, which means they are most active at dusk and dawn. They can travel up to 30 miles in a day and tend to travel six miles during a hunt. But because their territory is dwindling, food is not as plentiful, making it necessary for wild dogs to travel further to find food. They can reach speeds of 35 mi/h.

Different packs may have overlapping territories, but wild dogs are unique in that they do not tend to fight amongst themselves. Thus, territorial disputes are not likely in home ranges that encompass more than one pack. They are also unique in that unlike most large predators they do not use vocal calls to communicate to others where their territories lie. They do however mark their territories through scent. They secrete chemicals to communicate boundaries however, they do not mark their territory by urinating. The alpha pair will urinate around a site when the female is in heat, but they use urine more as a sign of dominance.

Interestingly, the Botswana Predator Conservation Trust (BPCT) is working to discover the chemical signals emitted by African wild dogs. This organization’s aim is to mimic these chemical signals and create artificial scents in order to deter the dogs from areas occupied by humans, farms in particular. Killing African wild dogs by gunshot, poison, or snaring to protect livestock is a serious conservation issue due to the damaging impact these actions have on the ever-decreasing dog population. BPCT hopes that African wild dogs will be deterred to go outside the National reservations if these artificial scents are placed on the outskirts of the parks. While the idea is encouraging, I wonder if this will be as effective as it is for wolves, which are unlike African wild dogs in that they are more overtly aggressive. If wild dog packs in the same areas are usually less aggressive compared to related species, logic would follow that the artificial markers would not have as great of a deterring effect as it would for a more aggressive species like the wolves. It would be interesting to compare the two!

https://www.eriezoo.org/PDFS/Animal%20Fact%20Sheets%20for%20Website/African%20Wild%20Dog.pdf

http://library.thinkquest.org/16645/wildlife/wild_dog.shtml

http://www.bbc.co.uk/nature/life/African_Wild_Dog

http://www.kalahari-predator-conservation.com/en/predators/african-wild-dogs

http://www.restek.com/Technical-Resources/Technical-Library/Editorial/editorial_A013

Last of a Dying Breed

An Endangered Species

Once wild dogs were a dominant predatory group across much of Africa. They roamed the great savanna, and played a crucial role in the ecosystem; culling the weak and sickly, maintaining the cycle. During and in some cases, prior to colonization, African wild dogs have been viewed as a threat to the local human inhabitants. This is especially the case following the ‘settling’ of Africa, during which the wild dogs were treated in much the same manner as the wolves of Europe; hunted, poisoned, and encroached upon to the point of extinction. 

Accordingly, there are less than 5,000 wild dogs left in all of Africa. Most populations are restricted to national parks which provide some degree of protection, yet isolate the groups, and risk increasing homogeneity in the gene pool. Moreover, they need enormous areas of several hundred square miles to range, and if the wild dogs venture out these few protected areas, they often come into conflict with people.
Of importance is not to view this as a simple problem faced by wild dogs which can be amended by human intervention. For example, people living in the Samburu Heartland have lost livestock to predators, that include African wild dogs. Fearing for their livelihoods, farmers and ranchers have to protect their own interests, which inevitably results in the direct targeting of any and all predatory species which pose a threat. This is essentially the same problem faced in the United States where efforts to reintroduce native wolf species have met strong resistance by ranchers, and local community residents. 

Conservation Efforts

Through study and potentially understanding of the species in terms of migratory patterns, hunting preferences it may be possible to enhance the degree to which this species may be protected. The African Wildlife Foundation (AWF), along with several other partners including the Samburu-Laikipia Wild Dog Project (SLWDP), local communities and NGOs, is working to strengthen and expand wild dog conservation throughout northern Kenya. However, given the travel patterns of wild dogs -easily travel 25 miles a day in search of prey over difficult terrain- it is incredibly challenging to study their habits. To expedite this research, AWF, with funding from the U.S. Agency for International Development (USAID) and the Dutch Government (DGIS), has employed 12 scouts from five different communities. AWF supplies these experienced trackers with the necessary equipment, and in addition, has initiated critical dialogue between local communities who live in wild dog areas and key researchers to ensure that landowners are well-informed about the research.

Other efforts which have been used in the US to facilitate coexistence of ranchers and wolves may well be applicable to the case of the African Wild Dogs. For instance, fladdery techniques and perhaps even conditioned taste aversion which have been shown to deter wolves from preying on livestock may be generalizable to wild dog populations in Africa. 

                                                       (African Wild Dog, Snared; help stop the war on the worlds species.)

References:

http://www.awf.org/content/wildlife/detail/africanwilddog

http://www.predatorconservation.com/wild%20dog.htm

http://www.bbc.co.uk/nature/life/African_Wild_Dog