4 o 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



Panama, and Darien), wing 103.5-112.1 ( 108.0), tail 47.6-52.5 (50.3), 

 oilmen from base 9.1-11.0 ( 10.2) , tarsus 9.6-10.9 (10.1) mm. 



Females (10 from Canal Zone, San Bias, eastern Province of Pan- 

 ama, and Darien), wing 100.0-104.1 (101.0), tail 45.0-49.0 (47.3), oil- 

 men from base 9.0-9.9 (9.3) , tarsus 9.5-10.7 (10.1) mm. 



Resident. Ranges throughout, from the lowlands to 1500 m in the 

 mountains of Chiriqui. They are seen commonly, singly, in pairs, or at 

 the proper season, with groups of young, over streams or ponds, and 

 also where earthen banks border roads. One or two may be noted 

 among flocks of winter migrant swallows from the north, but in general 

 these residents tend to feed and range apart. In late January 1957, at 

 Mandinga, San Bias, 100 or more circled in loose company at sunset, 

 feeding, and at intervals resting, in the open branches of a dead tree 

 until early dusk, when suddenly they disappeared to sleeping quarters 

 that I did not discover. At sunrise they came again to the tree to rest in 

 the sun. When I collected 5 at random to check their identity on the 

 morning of January 23, I was interested to find that all were females. 

 Throughout the Isthmus these flocks are recorded through February. 

 Then, in pairs or groups of half a dozen, they begin to examine the 

 steep earthen banks along the rivers where later they nest. In the last 

 week of March, along the Rio Jaque in eastern Darien, they were start- 

 ing to dig nest holes. Soon many were nesting, and through April their 

 breeding season was fully under way throughout their range. In early 

 June, near Sona, in the lowlands of western Veraguas, fully grown 

 young were on the wing. 



Males at times were protective of their nesting area against intru- 

 sion by other swallows. In late February 1960, on the Brackney farm 

 at Palo Santo, Chiriqui, a pair was preparing to nest in a low bank on 

 the shore of a small impoundment to water farm animals. The male 

 dove constantly at the small Blue-and-white Swallows that came to 

 drink and bathe. On one occasion he also pursued a single Vaux's Swift 

 that came down to the water. I was intrigued to observe that in the 

 long, swinging circles of their flight, the swift, in escaping, did not out- 

 distance the swallow. 



Like related swallows, these birds feed on small insects captured in 

 endless circling in the air. The only call that I have heard from them is 

 a low, harsh chip, a sound without great carrying power. 



I have noted that among this race of the Rough-winged Swallow 

 some dig their nest holes while others may use old burrows made by the 

 local kingfishers. The holes may be in the face of a perpendicular bank 

 along a stream, or along a cut bank beside a roadway, away from water. 



