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.