Dog days are just starting: the ecology invasion of free-ranging dogs (Canis familiaris) in a protected area of the Atlantic Forest

Abstract

Free-ranging dogs (Canis familiaris, Linnaeus, 1758) are highly invasive exotic species because of their ecological flexibility and adaptability and their close relationship with humans. They have occupied many protected areas around the world, threatening natural ecosystems and causing environmental damage. To understand the potential pressures of free-ranging dogs, we investigated three main aspects of their population ecology by placing camera traps in ecologically distinct locations of the Augusto Ruschi Biological Reserve (ARBR), southeastern Brazil. In this study, we assessed (i) the daily activity patterns according to circular kernel density function, (ii) the habitat selection according to occupancy models, and (iii) the population density according to spatial capture-recapture models. Free-ranging dogs in the ARBR are active irregularly (cathemeral behavior), display multiple daily activity peaks, and use approximately 73% of the study area. Our results suggest that free-ranging dogs exhibit broad temporal and spatial plasticity, so they can potentially harm a broad array of native species through competition or predation. The high temporal and spatial use range of free-ranging dogs is possibly a consequence of their high population density (0.55 ± SD 0.18 individuals/km2), representing one of the highest such estimates for the Atlantic Forest, and one that is higher than several estimates for ocelots, an ecologically similar native mesocarnivore. Our results suggest that the free-ranging dog population in the ARBR likely comprises a mix of domestic, stray, and feral individuals, with consequent management challenges that should focus on prevention, control, and perhaps eradication strategies.