FAMILY CAPRI MULGIDAE 201 



long sweeps and quick, erratic turns as insects appear in the air. When 

 food is abundant, as over the open waters of the larger rivers, flocks 

 of a hundred or so may join in scattered company. At other times 

 they feed singly. 



The small airstrips, now becoming common through the lowlands, 

 are favorite hunting grounds. And here after feeding they often 

 alight on the ground. In night-hunting with head lamps I have found 

 that their eyes do not glow like those of other goatsuckers. When I 

 have approached birds resting on the ground at distances of 75 meters 

 no reflection was seen until the birds turned the head so that the light 

 entered at an angle. Occasionally then I have perceived a very faint 

 sheen of yellowish green. At a distance of 3 meters the eye glows 

 ruby red, but farther away this color disappears. 



Small beetles have been the main food that I have found in the 

 stomachs of those taken for specimens. But the birds are opportunists 

 as they take any small insects that fly, including termites when swarm- 

 ing, and small diptera, particularly those that hover in clouds. 



The mouth lining in birds of this family is a thin, translucent sheet 

 through which the bones of the palate may be seen in dim outline, and 

 the bases of the large eyeballs show more clearly. The tissue of the 

 lining is tough and strong, as it needs to be to avoid damage from the 

 impact of hard bodied beetles taken when both bird and insect are in 

 swift flight. In the nesting season males utter a variety of trilling 

 notes and clucking calls, often when in close pursuit of a female. 

 Although in display they may dart down for a few meters they do not 

 produce the booming sound common in the other species of nighthawk. 

 When nesting is completed the birds are silent. 



The same superstition of potency as a love charm holds with the 

 nighthawk as with others of the family. At Jaque, Choco hunters 

 offered skins of these birds crudely removed and dried for trade in the 

 stores. They were reputed to bring 5 to 10 balboas apiece in Panama 

 City. 



Two geographic races of this species are found in Panama, one a 

 resident, and another that comes as a migrant from the north. Both 

 range together. 



When only small series of lesser nighthawks from Panama and 

 northern Colombia were available it was comparatively simple to 

 identify them to geographic race under the formula outlined by Ober- 

 holser (U. S. Nat. Mus., Bull. 86, 1914, pp. 94-112) in his review of 

 the genus Chordeiles, as it was assumed that all were migratory in 

 this area. With this premise, larger, darker specimens were allocated 



