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Status: Population size: 1,700 Photo by Chandler Robbins.

Puerto Rican Nightjar
(Caprimulgus noctitherus)

The endemic Puerto Rican Nightjar (Caprimulgus noctitherus) was described early in the twentieth century, but taxonomic consensus on its status as a full species distinct from the continental Whip-poor-will (Caprimulgus vociferus) did not emerge until the 1960s. The Spanish common name "Guabairo de Puerto Rico" is derived from the Taino Indian name. The nightjar once inhabited coastal lowlands all around western Puerto Rico, but habitat loss and introduced predators have now restricted it to a very small fraction of its former breeding range.

Identification
Active only after dark, the Puerto Rican Nightjar is rarely detected during daylight hours. Its excellent camouflage of mottled black, brown and gray, broken by a white band across the throat and white spots at the ends of the tail feathers, makes this robin-sized bird scarcely distinguishable from the leaf-litter on the forest floor where it rests motionless all day. Shortly after twilight, and again before dawn, the male may call from a tree branch, giving a rapid series of whistled "whip" notes. It is heard far more often than seen. Most sightings are mere glimpses of the bird in flight at dusk after it has betrayed its presence by vocalizing, but individuals may also make repeated foraging flights from favorite perches. The loud, distinctive territorial calling makes this species especially easy to census.

Distribution and Population Trends
The species is now found only in dry limestone forest along the southwest coast of the island, notably in the Bosque Estatal de Guanica (Commonwealth Forest of Guanica), where it is most numerous, but also in the Bosque Estatal de Susua, the Sierra Bermeja, and in hills near Guayanilla and Parguera. The present distribution represents only a small fraction (estimated at 3%) of the nightjar's former range, which is known to have included moist limestone forests along the north coast as far eastward as Bayamon, and may have extended inland to the lower cordillera.

Ecology
Puerto Rican Nightjars make short foraging flights from perches to capture night-flying insects. They feed almost entirely below the forest canopy. As in all caprimulgids, the wide gape is edged with stiff bristles to aid the bird in localizing its prey. Foraging activity may increase on bright moonlit nights, as calling has been observed to diminish at those times.

The territorial male is vocal throughout the year, but calling peaks at the height of the breeding season during April and May. The female lays 1 or 2 eggs directly on leaf litter under low bushes, constructing no nest. The light brown eggs are ringed and splotched with purple. Incubation is by both sexes and takes about 19 days. After hatching, the young chicks are moved away from the incubation site by the attending parents. Adults use distraction displays to lure predators away from their eggs or chicks. The young begin to fly in the third week after hatching, and become independent shortly thereafter.

Threats
Disturbances that could significantly threaten nightjars in their remaining forest refuges include tree cutting, road and utility line construction and maintenance, extensive recreational use of the forests, wild fires, and grazing by domestic stock. About half of the current nightjar habitat is in protected public forests, but the remainder, including lands adjacent to the public forests, is privately held forestland susceptible to conversion to other uses.

The mongoose (Herpestes jarvanicus) may have played an important role in eliminating nightjars from the moist forests of the north coast after its introduction to Puerto Rico in 1877. Any changes that make the dry forests in the southwest of the island more hospitable to mongooses or more accessible to dogs, cats, and rats could adversely impact the nightjar.

Conservation
The Puerto Rican Nightjar was federally listed as Endangered in 1973. The U.S. Fish and Wildlife Service approved a Puerto Rican Whip-poor-will (nightjar) Recovery Plan in 1984. The plan recommends research to gain knowledge of the population, range and natural history of the imperiled species, the cause of its decline, and potential threats to its survival. It also calls for protection of existing populations on both public and private lands, and education of the public against adverse habitat modification.

UNESCO has designated the Bosque Estatal de Guanica as a United Nations Biosphere Reserve, placing the home of the largest population of Puerto Rican Nightjars in an international conservation spotlight.

What Can You Do?
The Endangered Species Act has helped protect the Purto Rican Nightjar and made it possible to learn critical information about its biology. Audubon continues to work to ensure that this vital legislation is being used to protect our publicly-owned wildlife resources. Check out http://www.audubon.org/campaign/ to learn of the latest news about the Endangered Species Act and how you can help. To learn more about other species protected under this legislation, visit: http://endangered.fws.gov/

Support protection or acquisition of habitat on Puerto Rico by conservation agencies and organizations.

Become a member of the Society for the Conservation and Study of Caribbean Birds. See http://www.nmnh.si.edu/BIRDNET/SCO/.

Audubon is the U.S. representative of the global BirdLife International alliance. Our BirdLife partners in the Caribbean are developing Important Bird Areas programs to identify and conserve critical habitats that support birds and other wildlife. For more information on BirdLife IBA efforts throughout the Americas visit: http://www.birdlife.net/sites/index.cfm

For information about birds of Puerto Rico, including the Puerto Rican Nightjar, you can visit the website of the Sociedad Ornitologica Puertorrique?a: http://www.avesdepuertorico.org/main.htm

References
BirdLife International . 2000. Threatened birds of the world. Lynx Edicions and BirdLife International, Barcelona and Cambridge, UK.

Conservation Management Institute - Fish and Wildlife Information Exchange. 1996. Taxonomy - Puerto Rico Nightjar (Draft). http://fwie.fw.vt.edu/WWW/esis/lists/e104006.htm

Oberly, M.W. 2000. Puerto Rico's Birds in Photographs. Editorial Humanitas, San Juan, PR.

Raffaele, H., J. Wiley, O. Garrido, A. Keith, and J. Raffaele. 1998. A Guide to the Birds of the West Indies. Princeton University Press, Princeton, NJ.

U.S. Fish and Wildlife Service. Puerto Rican Nightjar Endangered Species Profile. http://ecos.fws.gov/servlet/SpeciesProfile?spcode=B04J