Ecologia espacial e temporal do canídeo Cerdocyon thous em uma floresta tropical seca: efeitos da disponibilidade de habitat, fragmentação e distúrbios antrópicos crônicos

Abstract

Habitat use by mammals is changing due to the profound anthropogenic alterations in natural landscapes. Determining which factors affect habitat use by species with distinct life histories is fundamental for understanding how communities are restructuring and to predict the anthropogenic impact on biodiversity. In this paper we tested the relative importance of habitat availability, fragmentation and chronic anthropogenic disturbance on the occupancy pattern and abundance of Cerdocyon thous, a generalist canid. Between May and September 2014, detection data were obtained by camera trapping in ten priority areas for conservation of the Caatinga dry forest (Northeast Brazil), totalling 179 sampling points and a total effort of 6,701 camera-days. Occupancy and GLM multiple regression models were used to test how occupancy and abundance of C. thous respond in relation to the explanatory variables: habitat availability, edge density, chronic anthropogenic disturbance (CDI), altitude and terrain rugosity. Subsequently, an alternative model was tested in which the habitat availability variable was decomposed into three natural habitats (forest, savanna and grassland formation), while CDI was decomposed into five vectors (human population, infrastructure, pasture, logging and fires). The models selected by Akaike's Information Criterion showed that C. thous responded positively to CDI in the abundance analysis, and to the vectors human population and pasture in both the occupancy and abundance analyses. Fragmentation positively influenced the abundance of C. thous. Although total native habitat availability negatively influenced C. thous occupancy, the species responded to habitat types differently. Forest had a negative effect on both occupancy and abundance while savanna had a positive effect for abundance when compared to grasslands. We conclude that the generalist canid Cerdocyon thous has benefited from the anthropization of natural environments, explaining why it has become one of the most abundant mammal in Brazilian dry forests.