Leaf litter depth and low canopy cover affect the detectability of the Brazilian Lancehead Bothrops jararaca (Wied-Neuwied, 1824) (Viperidae) in the Atlantic Forest

Precise estimates on the abundance and population size of a species are fundamental to the reliable evaluation of its conservation status. Demographic data can provide important insights into different aspects of the ecology, life history, and evolutionary history of a species, and can help to detect changes in population size, which is important in biological conservation. Here, we present the first systematic estimate of the abundance, detectability, and site occupancy of the Lancehead, Bothrops jararaca (Wied-Neuwied 1824), at Serra das Torres Natural Monument in the Atlantic Forest of Espirito Santo State, southeastern Brazil. To understand better the ecological factors driving occupancy, we also analyzed the principal habitats used by B. jararaca. We used the Rapid Assessment method to sample a B. jararaca population between January and March 2018 using active searching and pitfall traps. We applied the Royle-Nichols occupancy model to estimate the abundance of B. jararaca, as well as single-season, single-species occupancy models to analyze the types of habitats in which B. jararaca was most frequently detected. We recorded 47 juveniles and adults of B. jararaca (1.5 snakes per sampling day) and estimated an abundance of 137 +/- 25 (mean +/- SE) individuals for the sampled area within the MONAST. We found higher detectability in deeper leaf litter and higher detectability where there was a low percentage of canopy cover. Our results advance the understanding of snake population dynamics and contribute to the knowledge of the abundance patterns of B. jararaca.