Ecology and Demography of Free-Roaming Domestic Dogs in Rural Villages near Serengeti National Park in Tanzania

Abstract

Free-roaming dogs (Canis lupus familiaris) are of public health and conservation concern because of their potential to transmit diseases, such as rabies, to both people and wildlife. Understanding domestic dog population dynamics and how they could potentially be impacted by interventions, such as rabies vaccination, is vital for such disease control efforts. For four years, we measured demographic data on 2,649 free-roaming domestic dogs in four rural villages in Tanzania: two villages with and two without a rabies vaccination campaign. We examined the effects of body condition, sex, age and village on survivorship and reproduction. Furthermore, we compared sources of mortality among villages. We found that adult dogs (>12mos) had higher survival than puppies in all villages. We observed a male-biased sex ratio across all age classes. Overall survival in one non-vaccination village was lower than in the other three villages, all of which had similar survival probabilities. In all villages, dogs in poor body condition had lower survival than dogs in ideal body condition. Sickness and spotted hyena (Crocuta crocuta) predation were the two main causes of dog death. Within vaccination villages, vaccinated dogs had higher survivorship than unvaccinated dogs. Dog population growth, however, was similar in all the villages suggesting village characteristics and ownership practices likely have a greater impact on overall dog population dynamics than vaccination. Free-roaming domestic dogs in rural communities exist in the context of their human owners as well as the surrounding wildlife. Our results did not reveal a clear effect of vaccination programs on domestic dog population dynamics. An investigation of the role of dogs and their care within these communities could provide additional insight for planning and implementing rabies control measures such as mass dog vaccination.

Predation by small mammalian carnivores in rural agro-ecosystems: An undervalued ecosystem service?

“…We suggest that such a scenario is most likely prevalent in rural African landscapes were local fauna often form part of the diet of people in rural areas (Holmern et al, 2006). Furthermore dogs, especially when roaming freely (a scenario common in African rural landscapes (Czupryna et al, 2016)), can kill small carnivores (Ralls and White, 1995). Finally, dogs are often used during hunting activities where they can kill non-target species such as small carnivores (Holmern et al, 2006).…”

The African Lion: A Long History of Interdisciplinary Research

“…The CDP simultaneously monitored disease status in the Serengeti/Ngorongoro lions and the domestic dogs that live in villages surrounding the Serengeti National Park and within the Ngorongoro Conservation Area. The project has inoculated around 50,000 dogs per year starting in 2002 (Czupryna et al, 2016). The wild dogs (Lycaon pictus) in the Serengeti had suffered from periodic disease outbreaks in the 1960s and rabies was positively diagnosed in 1990 (Gascoyne et al, 1993).…”

No evidence of handling‐induced mortality in Serengeti's African wild dog population

“…This is because (a) the domestic dog population, a reservoir host for rabies (Lembo et al, 2008), has increased in size (Craft et al, 2017), with an annual growth rate of up to 8% in certain parts of the ecosystem (Czupryna et al, 2016) and (b) the surviving wild dog population occurs sympatrically with domestic dogs, and it is thus reasonable to assume that the current wild dog population has even greater rates of exposure to the rabies virus than the portion of the wild dog population formally resident within SNP, which is almost entirely free of domestic dogs. Several cases of rabies have been reported from the areas adjoining SNP post-1991 (Lembo et al, 2008), and over 40% of village members in NCA reported the presence of wild dogs at their households (Czupryna et al, 2016), confirming the sympatric occurrence of domestic dogs and wild dogs. Thirdly, wild dogs are exposed to similar types of interventions, that is immobilization and collaring , and the same types of handling that allegedly resulted in individual and pack mortality in SNP (Burrows et al, 1994).…”

“…Secondly, contact with domestic dogs increases exposure to rabies (Woodroffe et al, ) and therefore, rates of exposure are expected to be at least the same or higher than those experienced 20 to 30 years ago in SNP. This is because (a) the domestic dog population, a reservoir host for rabies (Lembo et al, ), has increased in size (Craft et al, ), with an annual growth rate of up to 8% in certain parts of the ecosystem (Czupryna et al, ) and (b) the surviving wild dog population occurs sympatrically with domestic dogs, and it is thus reasonable to assume that the current wild dog population has even greater rates of exposure to the rabies virus than the portion of the wild dog population formally resident within SNP, which is almost entirely free of domestic dogs. Several cases of rabies have been reported from the areas adjoining SNP post‐1991 (Lembo et al, ), and over 40% of village members in NCA reported the presence of wild dogs at their households (Czupryna et al, ), confirming the sympatric occurrence of domestic dogs and wild dogs.…”