Breeding microhabitat patterns among sympatric tropical larids

The selection of breeding microhabitat (nesting sites) affects successful reproduction in seabirds, yet the process of nesting-site selection in sympatric tropical species remains poorly known. During the 2021 breeding season, we assessed nesting-site selection among five larid species at three cays of Cuba and quantified explanatory variables. Random forest classification models were used to assess which landscape features among eight variables best explained site selection by each species. Patterns were clear for most species, especially the highly gregarious Roseate Tern Sterna dougallii, Royal Tern Thalasseus maximus, and Sandwich Tern T. sandvicensis. Patterns were consistent among the study cays. Dominant plant species, minimal distance to cay edge, vegetation cover, and substratum at nesting sites were among the more important explanatory variables. Interspecific differences in nesting-site selection may be important for the assemblage of multispecific colonies by reducing aggressive interactions, competition, and breeding failures.