Cooperative Fish and Wildlife Research Units Program: Mississippi
Education, Research and Technical Assistance for Managing Our Natural Resources

The Puerto Rican Nightjar Caprimulgus noctitherus is an endangered caprimulgid endemic to coastal dry and lower montane forests of southwest Puerto Rico. I studied nest habitat use of this nightjar at the Guánica Biosphere Reserve in southwestern Puerto Rico. Nightjar nests (n = 23) were located in evergreen and deciduous forest and were more common at elevations above 100m. Nests were located from 2 m to 125 m into the forest from the nearest road or trail and were characterized by a deep layer of leaf litter, and an open midstory beneath a closed canopy. Six of the 10 nests found in evergreen forest were located within abandoned mahogany (Sweetenia mahogany) plantations. Habitat structure and vegetation composition were quantified at each nightjar nest and an equivalent number of randomly selected sites. Four of 13 habitat variables differed significantly (P < 0.05) between nest and random sites and included; elevation, leaf litter biomass, midstory stem density, and canopy closure. Stepwise logistic regression generated a best model describing nightjar nest habitat. Leaf litter biomass, midstory stem density, and canopy closure correctly classified 77.3% of nightjar nests. Management of forest stands at higher elevations to promote nightjar nest habitat structure, protection of private lands in the periphery of the Guánica Biosphere Reserve, and acquisition of privately owned forest tracts in other portions of the nightjar’s range will insure the long-term persistence of the species.