FAMILY APODIDAE 225 



Resident. Tolerably common; seen in the sky throughout the Re- 

 public from the lowlands to the higher mountains. Isla Coiba. 



In a family noted for rapid flight, this large species equals, or may 

 surpass, any of its smaller relatives. The white-collared swifts are 

 social, found often in bands of a dozen, and frequently in larger 

 numbers up to a hundred or more. Their day is spent on the wing in 

 rapid, tireless movement through the air, regularly high above the 

 earth, and as regularly in dashing course lower when the ground is 

 clear. Occasionally I have seen them swing down to dip the bill in the 

 water on rivers or ponds. Those I have secured for specimens have 

 been shot from groups that made regular passes over some open area 

 where I could see them fall, as their momentum often carries them 

 many meters before they strike the ground. 



Circling flocks may range so high as to be mere specks in the sky. 

 In Bocas del Toro I have noted 200 or more milling swiftly in a huge 

 ball formation prior to a heavy rain. I have observed also that they 

 avoid storms or fog by rapid flights toward areas where the air is clear. 

 Rarely, when strong, steady winds swept across mountain slopes, they 

 may hang motionless with widespread wings for a minute or more. 

 Apparently this is a form of display as sometimes two have ap- 

 proached, slowly raising the wings alternately, first one and then the 

 other. On other occasions two or three in rapid chase have come 

 spiraling down from high in air. Flocks near at hand may utter low 

 chattering calls. Their preference is for flight above land as I have 

 never observed them far at sea, nor have I recorded them over off- 

 shore islands, with the exception of Isla Coiba, in itself a large land- 

 mass. 



In western Chiriqui, where flocks circled at sunset over pasture- 

 lands, as dusk neared they swung off toward distant mountain cliffs 

 where I supposed they spent the night. Tails and the tips of the 

 primaries often are much worn. Snow (Zoologica, vol. 47, 1962, p. 

 130) records that the race albicincta is migratory on the island of 

 Trinidad. He believes that "it is likely that at least on occasions they 

 spend the night in the air, as the European Swift Apus apus has been 

 found to do." 



An egg in the British Museum (Natural History), received in the 

 Salvin-Godman collection, from Frontino, Antioquia, is dull white in 

 color, somewhat stained, and is long elliptical in form. It measures 

 33x22.4 mm. Regarding it Sclater and Salvin (Proc. Zool. Soc. 

 London, 1879, p. 531) quote Salmon, who collected it when resident 

 at Medellin, as stating that this bird "makes a nest of mud and moss 



