Wild and feral mammals in a natural area in Mexico City, Mexico

Mexico City, one of the largest urban areas in the world, continues to expand into natural landscapes, threatening native biodiversity. The Sierra de Guadalupe (SG), a protected mountainous area in the city's northern region, represents a critical refuge for wildlife. However, the presence of feral mammals—particularly domestic species exhibiting wild behavior—poses serious ecological and public health risks. From February 2020 to August 2021, we conducted 20 survey walks and 255 camera-trap days across SG to assess the composition and relative abundance of medium-sized mammals. We identified nine species, with dog (Canis lupus familiaris) (24 %) emerging as the most frequently detected. Behavioral indicators—such as gregariousness, robust body condition, and lack of human proximity—suggested that many dogs exhibited feral characteristics. In contrast, species such as gray fox (Urocyon cinereoargenteus) and cacomixtle (Bassariscus astutus) showed lower relative abundances, suggesting potential displacement. Species richness estimation (Chao2) confirmed that all predicted species were recorded. No significant seasonal variation in domestic animal presence was found, but spatial analysis revealed higher abundances near urban-adjacent entrances. Testimonies from local residents corroborated the presence of dog packs and reported incidents of aggression toward people, livestock, and wildlife. Our findings highlight the urgent need for ethical and ecologically informed management strategies to control feral mammal populations. Reducing their abundance will help mitigate zoonotic disease risks and support long-term conservation efforts in urban natural areas.