l88 BIRDS OF THE REPUBLIC OF PANAMA — PART 2 



though at times they have been recorded roosting in the open. As most 

 of the fruits eaten are aromatic, Snow (Zool., vol. 47, pt. 4, 1962, 

 p. 217) believes that the bird in its search for food may be guided by 

 an olfactory sense. 



Family NYCTIBIIDAE: Potoos; Leonas y Urutaus 



The species of this family differ from the related nighthawks and 

 typical goatsuckers in much larger size, and also in their daytime pose, 

 in which they rest on the end of a small stub, or on a knob projecting 

 from a large branch or tree trunk. Here they sit motionless with the 

 tail hanging straight down, the bill pointing up, and the lids covering 

 the large eyes closed to a barely perceptible slit. With their mottled 

 gray and brown pattern they mimic so perfectly the wood that they 

 seem a part of it. Because of their large size persons not familiar with 

 birds in detail usually class them as owls. Anatomically, they differ 

 externally from the true goatsuckers in the presence of prominent 

 powder down patches, a sharply angular projection on the side of the 

 maxilla, lack of a pecten or comb on the middle claw, and a very short 

 tarsus, only half as long as the inner toe. 



The five species are confined to the warmer lowlands of the Amer- 

 icas. Two range in Panama. 



KEY TO THE SPECIES OF NYCTIBIIDAE 



Size very large ; wing 345 to 382 mm., tail 219 to 265 mm. ; lesser wing coverts 

 black, mottled with brown Great potoo, Nyctibius grandis grandis, p. 188 



Size smaller; wing 264 to 282 mm., tail 174 to 196 mm.; lesser wing coverts 

 plain black Lesser potoo, Nyctibius griseus panamensis, p. 191 



NYCTIBIUS GRANDIS GRANDIS (Gmelin) : Great Potoo; 

 Leona 



Caprimulgus grandis Gmelin, Syst. Nat., vol. 1, pt. 2, 1789, p. 1029. (Cayenne.) 



A nocturnal bird, goatsuckerlike in form of body and head, equal 

 in size to the larger owls. 



Description. — Length 450-510 mm. Two color phases, one grayer, 

 the other washed more or less heavily with buffy brown. Adult 

 (sexes alike), above with the ground color mixed gray, or buffy 

 brown and white in varying amount, barred lightly or heavily, and 

 mottled with gray, fuscous and sooty brown ; outer wing coverts sooty 

 black, lined with brown ; primaries and secondaries black, barred 

 indistinctly with dull gray, with the outer webs marked heavily with 



