Habitat use and movement patterns of broad-snouted caimans (Caiman latirostris) in an impacted Atlantic forest environment in Brazil

Abstract

BackgroundAnimal habitat use can be influenced by a suite of factors including intraspecific interactions and resource availability. The broad-snouted caiman (Caiman latirostris) is the largest crocodylian species distributed in freshwater environments of the Brazilian Atlantic Forest, where it inhabits many types of human-impacted and preserved habitats. Despite their ability to occupy ecologically different water bodies, little is known about their movement patterns and their habitat use. We investigated the variation in movements and space use of adult caimans relative to sex, body condition, and environmental conditions in northeastern Brazil.MethodsWe conducted long-term capture surveys from 2013 to 2022 and used GPS telemetry from 2021–2022 (n = 12 individuals) to assess movement patterns and home ranges of caimans and their habitat use based on Brownian Bridge Movement Modeling (BBMM) and Generalized Linear Mixed Modeling (GLMM).ResultsFemales ranged farther from reservoir’s forested margins, exploring a greater diversity of habitats during the wet/non-reproductive season. During the dry/reproductive season, females remained close to nesting sites within forest fragments. The body condition of caimans did not change significantly over the wet and dry season, indicating that resources are available year-round. Caimans moved more at night than during daytime, likely due to nocturnal foraging and possibly avoiding periods of increased human activity. Female movement rates were positively associated with rainfall, in a pattern likely linked to nest attendance in the dry season. Male movement was positively correlated with reservoir volume in the wet season, possibly due to increased availability of habitats in comparison to dry periods and to decreased overlap with territories controlled by other males. Home ranges estimated as 95% utilization distributions were relatively small in both sexes, averaging 0.64 km2 (range: 0.001–1.4 km2), as were their core areas estimated as 50% utilization distributions, which averaged 0.12 km2 (range: 0.0003–0.12 km2). Small core areas may indicate that caimans remain most of their time in a specific habitat, suggesting abundant resource availability or territoriality.ConclusionsOur work reveals the complexity of social interactions and how caimans select their habitats in a highly altered environment.