Les hommes ont oublié cette vérité. Mais tu ne dois pas l'oublier, dit le renard. Tu deviens responsable pour toujours de ce que tu as apprivoisé.
Le Petit Prince, chap. 21

Wednesday, 3 July 2013

Dogs in rural Zimbabwe: disease transmission and competition with scavengers

Butler, J. R. A., & Toit, J. T. (2002). Diet of free‐ranging domestic dogs (Canis familiaris) in rural Zimbabwe: implications for wild scavengers on the periphery of wildlife reserves. Animal Conservation5(1), 29-37.
Numbers of free-ranging dogs (Canis familiaris) have reached unprecedented levels in Zimbabwean communal lands (agropastoralist rural areas). This study examined the potential competitive interactions between dogs and wild scavengers on the boundary of Gokwe Communal Land (GCL) and the Sengwa Wildlife Research Area (SWRA) in 1995–96. Dietary studies showed that dogs were primarily scavengers of human waste and animal carcasses. Twelve experimental carcasses indicated that dogs were the most successful species in the vertebrate scavenger guild, consuming 60% of available biomass and finding 66.7% of carcasses. Dogs monopolized the supply of domestic animal carrion within GCL, but also consumed wild carrion up to 1 km within the SWRA, and were seen 3 km inside the reserve. Their principal competitors for carcasses were vultures, and to a lesser degree lions (Panthera leo), leopards (P. pardus) and spotted hyaenas (Crocuta crocuta). Dogs outcompete vultures on wildlife reserve boundaries owing to their high densities, nocturnal and diurnal activity, physical dominance and greater tolerance of human disturbance. With a population growth rate of 6.5% per annum the influence of dogs will intensify on the peripheries of reserves, exacerbating their existing threat to wild scavengers. This scenario is probably occurring in many other African countries.

Butler, J. R. A., Du Toit, J. T., & Bingham, J. (2004). Free-ranging domestic dogs (Canis familiaris) as predators and prey in rural Zimbabwe: threats of competition and disease to large wild carnivores. Biological Conservation, 115(3), 369-378.

Domestic dogs (Canis familiaris) arrived in Zimbabwe ca. 1000 years ago. Numbers of free-ranging dogs have reached unprecedented levels in communal lands (agro-pastoralist rural areas), and interact with large wild carnivores along boundaries with wildlife reserves as predators and prey. This study examined a population of 236 dogs in a 33-km2 section of Gokwe Communal Land (GCL) bordering the Sengwa Wildlife Research Area (SWRA) in north-western Zimbabwe in 1995–1996. Dogs were found up to 6 km within the SWRA, and were the most common carnivore on the GCL–SWRA boundary. Observations of 16 radio-collared dogs showed that they were inefficient predators. Only 20 kills were recorded amongst the remaining dog population, of which three were wild ungulates. Dogs were unsuccessful predators due to their small group size (mean 1.7) and body mass (mean 14.7 kg), and the abundance of alternative food. It is therefore unlikely that they compete with large carnivores for wild prey. However, leopards (Panthera pardus), lions (P. leo) and spotted hyaenas (Crocuta crocuta) preyed on dogs in GCL, removing ⩾6% of the dog population in 1993. Such predation provides ideal circumstances for disease transmission. Canid disease was prevalent in the study area; including rabies and probably distemper. The risk of infection is greatest during the dry season (May–October), when peaks in rates of disease, carnivore incursions into GCL, and predation on dogs coincided. The role of jackals (Canis adustus and Canis mesomelas) and spotted hyaena predation of dogs is discussed in relation to disease epidemics within wildlife reserves. With a dog population growth rate of 6.5% per annum, and the prevalence of canid diseases, the conservation threat posed by dogs is escalating on communal land–wildlife reserve boundaries in Zimbabwe. Measures to control dog numbers and improve vaccination coverage of dogs are discussed.

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