Nest-Cavity Selection and Nesting Success of Bermudian White-Tailed Tropicbirds (Phaethon lepturus catesbyi)

Abstract

ABSTRACT Breeding cavity-nesting seabirds on remote, oceanic islands are threatened largely by destruction of nest cavities and introduced predators. In response, artificial cavities are often implemented as a conservation strategy. Effective artificial cavity programs require recognition of specific nest-site characteristics, which can be major determinants of survival and persistence of cavity-nesting seabirds. In Bermuda, we monitored 158 natural and 178 artificial cavities of the White-tailed Tropicbird (Phaethon lepturus catesbyi) from 2013–2015 to determine if specific nest-site characteristics could explain cavity selection, nest survival, and predation by introduced rats (Rattus spp.) and the American Crow (Corvus brachyrhynchos). We found that tropicbirds preferred natural cavities lined with sand, and which had smaller entrances and were located on steeper cliffs. Occupancy of artificial cavities on the mainland varied across years and increased with cavity depth, whereas neither variable had an...