African Wild Dog Recovery: A Case Study in Kenya

African wild dogs (Lycaon pictus) are large, highly social, and charismatic canids (Figure 1). Unfortunately, competition with lions and hyenas, persecution by humans, and disease all contributed to the decline in African wild dog populations in recent years. They are now listed as endangered species by the International Union for the Conservation of Nature/Species Survival Commission (IUCN/SSC). African wild dogs now roam over only 7% of their once vast range.

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Figure 1. A pack of African wild dogs (Lycaon pictus) preparing for a hunt. (From R. Lamb)

Biologists hypothesize that three factors are largely responsible for declining wild dog populations in Africa.

1) Anthropogenic factors including habitat fragmentation, retaliation killings for livestock losses, road kills, and diseases from domestic dogs.

2) Direct or indirect competition from other large, social carnivores, especially lion prides and hyena clans.

3) When pack size falls below a certain threshold, survival and reproduction become compromised –
Allee effect.

It is relatively easy to see how the first two hypotheses might lead to population declines. The Allee effect (named after Warder Clyde Allee who first proposed the phenomenon) takes a bit more explanation. Essentially, it describes a situation where smaller populations suffer ever-declining survival and reproductive success. For example, assume that both anthropogenic factors and competition with other carnivores leads to declines in African wild dog populations. Smaller pack size leads to fewer offspring being produced, especially in cooperatively breeding species where only the alpha female usually breeds. Low reproductive output leads to even smaller packs size and even lower reproductive output, and eventually the loss of the pack altogether.

But which hypotheses are most important and where should conservation biologists focus their efforts? After all, different management policies would be needed depending on which factors were most important in causing African wild dog population declines.

A decade long study of recovering African wild dog populations in northern Kenya by Dr. Rossie Woodroffe may shed some light on the issue. She observed a natural recovery of wild dog populations living on private and community land in northern Kenya between 2000 and 2008. Wild dog populations had all but disappeared from the region by the 1980s but began to return in 2000 (Figure 1). Dr. Woodroffe radiotracked 19 packs in two distinct areas: community lands used by Samburu and Masai pastoralists, and private lands owned by commercial ranchers. Community lands had higher human population density and greater potential for anthropogenic threats, while the private ranches in the southwestern region had sparse human populations but higher densities of lions and hyenas. In effect the region provided a natural test of the hypotheses thought to constrain African wild dog populations.

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Figure 1. African wild dog population size over time in the Kenya. Solid symbols are totals for the entire study area, and open symbols are for only the Laikipia District. (From Woodroffe, 2011)

Interestingly, wild dog populations in this region went from almost nil to become the 6th largest in the world.
Woodroffe (2011) showed that reproductive rates and mortality rates were similar on community lands and private lands. As predicted by the Allee effect, larger packs raised larger numbers of pups. However, even small packs were successful in raising pups and eventually increased in size (Figure 2). Moreover, pack extinction was unrelated to pack size, suggesting that there was no “critical pack size” as predicted by the Allee effect.


Figure 2. Diagram depicting the life-cycle of African wild dogs. Percent above arrowwilddogflowcharts represent rates survival between the three life stages (pup, yearling, adult). Numbers in italics below the arrows represent elasticity and sensitivity of the estimated population change to changes in survival rates. (From Woodroffe, 2011)

Woodroffe’s results are encouraging as they show that African wild dog populations can rapidly recover even in regions with high human/livestock densities. As Woodroffe states, “this recovery was probably facilitated by local pastoralist traditions, which combine vigilant herding of livestock with little or no hunting of wild prey.” If so, management policies that encourage more traditional pastoralism may aid in the recovery of African wild dogs in other human-dominated landscapes.

References

Woodroffe, R. (2011) Demography of a recovering African wild dog (
Lycaon pictus) population. Journal of Mammalogy, 92:305-315.