Predicting suitable nesting sites for the Black caiman (Melanosuchus niger Spix 1825) in the Central Amazon basin

Abstract

After many years of illegal hunting and commercialization, the populations of the Black caiman (Melanosuchus niger) have been recovering during the last four decades due to the enforcement of a legislation that inhibits their international commercialization. Protecting nesting sites, in which vulnerable life forms (as reproductive females, eggs, and neonates) spend considerable time, is one of the most appropriate conservation actions aimed at preserving caiman populations. Thus, identifying priority areas for this activity should be the primary concern of conservationists. As caiman nesting sites are often found across the areas with difficult access, collecting nest information requires extensive and costly fieldwork efforts. In this context, species distribution modeling can be a valuable tool for predicting the locations of caiman nests in the Amazon basin. In this work, the maximum entropy method (MaxEnt) was applied to model the M. niger nest occurrence in the Mamirauá Sustainable Development Reserve (MSDR) using remotely sensed data. By taking into account the M. niger nesting habitat, the following predictor variables were considered: conditional distance to open water, distance to bare soil, expanded contributing area from drainage, flood duration, and vegetation type. The threshold-independent prediction performance and binary prediction based on the threshold value of 0.9 were evaluated by the area under the curve (AUC) and performing a binomial test, respectively. The obtained results (AUC = 0.967 AE 0.006 and a highly significant binomial test P < 0:01) indicated excellent performance of the proposed model in predicting the M. niger nesting occurrence in the MSDR. The variables related to hydrological regimes (conditional distance to open water, expanded contributing area from drainage, and flood duration) most strongly affected the model performance. MaxEnt can be used for developing community-based sustainable management programs to provide socioeconomic benefits to local communities and promote species conservation in a much larger area within the Amazon basin.

Science and conservation of Amazonian crocodilians: a historical review

“…It has been proposed that protecting nesting sites (Da Silveira & Thorbjarnarson, 1999; Thorbjarnarson & Da Silveira, 2000; Villamarín et al, 2011) and establishing an upper size limit (Campos et al, 2008) would contribute to maintaining viable populations on a long‐term management basis, avoiding females, which have a smaller size. To this end, geographical information systems and remote sensing coupled with nest surveys are useful tools to identify nesting sites at large scales and may guide management activities (Banon, Arraut, et al, 2019; Banon, Banon, et al, 2019; Da Silveira & Thorbjarnarson, 1999; Villamarín et al, 2011).…”

Biotic Indicators for Ecological State Change in Amazonian Floodplains

“…1994) and crocodilians (e.g., Melanosuchus niger , Villamarín-Jurado and Suárez 2007 ) often is limited due to their prolonged incubation times and need of large volumes of vegetation for nest construction (e.g., M. niger , Banon et al. 2019 ). This may lead to an increased frequency of communal nesting sites (e.g., Caiman crocodilus, Cunha et al.…”

The role of topographic-derived hydrological variables in explaining plant species distributions in Amazonia

“…The HAND algorithm has been used for ecological applications previously (Banon et al 2019;Zuquim et al 2021). Its applicability, however, is still limited by the need of validation points.…”