Nesting distribution of masked booby sula dactylatra at trindade island, western south atlantic ocean

The Masked Booby Sula dactylatra is a surface-nesting seabird that breeds on offshore islands across the tropical and subtropical oceans. On inaccessible rocky areas on Trindade Island, located about 1 200 km from Espirito Santo, Brazil, the nesting of this species has been poorly studied. To model the species' nesting habitat suitability at Trindade Island, we mapped active nests during the breeding seasons of 2017 and 2019, from October to November, using a hand-held Global Positioning System receiver and an Unmanned Aerial Vehicle. In order to identify key areas, we created nesting habitat suitability maps using seven different algorithms (Random Forest, Gradient Boosting Machine, Artificial Neural Network, Maximum Entropy, Generalized Additive Model, Generalized Linear Model, and Multiple Adaptive Regression Splines) in response to five topographical variables and one vegetation-related variable. Our sample included 87 active nests. Models generated by all four best algorithms were considered satisfactory. Results indicate that elevation and terrain aspect are the main variables influencing booby selection of nesting sites. We found areas of very high nesting habitat suitability along the southwest and northwest faces of the island, mostly in elevations varying from 150 m to 450 m.