Human behaviors determine the direct and indirect impacts of free-ranging dogs on wildlife

Abstract

Dogs (Canis familiaris) are among the most abundant and widely distributed carnivores worldwide, and their presence can have negative impacts on native fauna. This study investigated the invasion of cacao agroforests by free-ranging dogs in Brazil. By monitoring the behavior of dogs using direct observations, we assessed whether direct (chasing and predation) and indirect (urine and fecal deposition) interactions with wildlife are more common when dogs enter the agroforests with humans than when they stay outside. We also compared the time that dogs spent inside versus outside the agroforests, and estimated their areas of use. The dogs (n = 10) spent a small fraction of the time without their owners, and only when moving inside the cacao agroforests. The dogs fed and rested more in open habitats and house surroundings than in agroforests, but they were more active and depredated wildlife exclusively in the latter. Kernel estimates of space use at the 50% and 95% levels ranged from 1 to 46 ha and 6 to 202 ha, respectively. Most of the area used by dogs was within cacao agroforest, while core areas were concentrated near human residences and in places of owner permanence in cacao agroforest. Human movement was a key determining factor in the use of space by the dogs. Changes to human behaviors toward their dogs must be considered if the direct and indirect impacts of dogs on wildlife are to be mitigated.