The colonies are very dense, with multiple partners on same tree. Before and during breeding, pairs and groups dash headlong from interior down valleys to the sea. Nesting adults and immatures at nest give bursts of rapid, vibratory nodding.
In Costa Rica it breeds from March to September. The nest is a substantial, shallow cup of compacted vegetable materials (seaweed, moss, dead leaves) cemented together with excrement; placed on horizontal limb of tall, open tree (especially Ochroma pyramidale or Cecropia sp.) or palm. Puts 1 egg, buff to creamy, blotched and speckled with reddish-brown and dark brown. Incubation lasts 30 - 37 days and the chicks are born covered with blackish down. Juveniles leave the nest at 48 - 60 days and remain with their parents several weeks.