The species frequents the drier, more open sec- 

 tions of the Susua Forest and has not been found 

 in the riparian forests or the denser scrub at eleva- 

 tions above 350 m (Kepler and Kepler 1973). 

 The Guanica forest, where whip-poor-wills occur 

 most commonly, has an annual rainfall of 750 

 mm, contrasting with an annual water loss through 

 evaporation and plant transpiration of 2,000 

 mm. The porous limestone permits no standing or 

 running fresh water anywhere. Elevations range 

 from sea level to 230 m. Semideciduous vegeta- 

 tion consists of hardwood trees on top of Ume- 

 stone hills, normally above 75 m. Below this, par- 

 ticularly on the southern slopes, forest changes 

 to mixed cactus and semideciduous growth. The 

 canopy is 4 or 5 m high, with some trees 6-7 m. 

 Important species include Pisonia alba, Swietenia 

 mahogoni. Acacia famesiana and Bursera sima- 

 ruba. There is no well-marked stratification or 

 epiphytic flora. Whip-poor-will population cen- 

 tered on higher slopes of central hills coincident 

 with semideciduous forest. They are largely ab- 

 sent from south-facing slopes below 75 m domin- 

 ated by cactus, open patches of grassland and 

 scrub, and thickets of Agave (Kepler and Kepler 



1973). 



Susua Commonwealth Forest is xeric scrub on 



steep rounded hills of decomposed serpentine 

 soils. It receives 1500 mm of rain per year. The 

 elevation is 100 to 430 m. Two permanent streams 

 support a lush riparian plant life less than 100 m 

 in width. Scrub 4-5 m high predominates 50 or 

 more meters from streams and extends to hill 

 tops, where it becomes much denser. The Puerto 

 Rican whip-poor-wiU occurs here in small num- 

 bers but not in riparian habitat. Greatest numbers 

 occur in open scrub forest with horizontal visibil- 

 ity from 5 to 7 m. None are found in denser sec- 

 tions where visibility dropped to 3 m. Susua For- 

 est is considered suboptimal habitat for whip- 

 poor-wills based on only one pair in 14.1 hectares 

 as compared with one pair in no more than 6.9 

 hectares in Guanica Forest (Kepler and Kepler 

 1973). 



FOOD AND FORAGING 



The whip-poor-wUl captures flying insect prey 

 by flying from perches well above the 

 ground. It has favorite perches used regularly for 

 feeding in the evening and ventures from 

 forest canopy protection after dark to more 



isolated trees for feeding perches (reported by 

 Cotte in Kepler and Kepler 1973). 



SHELTER REQUIREMENTS 



It requires the shelter of low scrubby forest 

 and undergrowth for daytime concealment and 

 nesting (Kepler and Kepler 1973). 



NESTING AND BEDDING 



The species nests on leaf litter of the forest 

 floor without additional nest material. 



It roosts on the ground or on branches of 

 trees beneath cover of leafy canopy (Kepler and 

 Kepler 1973). 



RITUAL REQUIREMENTS 



Vocalizations are thought to proclaim terri- 

 tory possession and determine spacing of breeding 

 pairs (Kepler and Kepler 1973). 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



Predation by introduced mongoose and 

 domestic cats and dogs should be controlled ; also 

 overbrowsing of habitat by domestic livestock, 

 particularly goats, should be prevented. 



POPULATION NUMBERS AND TRENDS 



Subfossil bones were found in a cave near 

 Morovis (Wetmore 1919, 1922; Storrs Olson pers. 

 comm. 1977). Cory (1889) reported receipt of a 

 specimen later used as the type specimen. Wet- 

 more (1919, 1922, 1927; Wetmore in Reynard 

 1962) during 10 months field work in Puerto 

 Rico in 1911 and 1912 saw only one bird that he 

 thought might belong to this species. It was 

 thought to be extinct (Bond 1940; Greenway 

 1958) until rediscovered in 1961 near Guanica by 

 Reynard (1962) who collected one male and heard 

 six others nearby. Leopold (1963) estimated the 

 Guanica population as about 25 pairs. Bond (1962) 

 reported "numerous individuals heard on semi- 

 arid hills near the coast." J. B. McCandless esti- 

 mated that as many as 100 birds remained within 

 the Guanica Forest (Kepler and Kepler 1973). 

 During the period 1969-1971, total Guanica pop- 

 ulation was estimated at about 400 breeding pairs, 

 based on a density of one pair per 6.9 hectares to 

 one pair per 4.9 hectares (Kepler and Kepler 



