FAMILY H1RUNDINIDAE 



is 



an irregular black mark variable in size, on foreneck, most prominent 

 in adult males, in females often much restricted; sides more or less 

 brownish gray; breast and abdomen white. 



Immature, colors much duller; feathers of the upper surface usually 

 with paler margins, and color patterns as a whole less definite. 



Cliff Swallows are seen mainly in fall, and in the months of spring, 

 from late February through April, usually in company with other mi- 

 grant species of the family. It is probable that their principal winter 

 quarters are in South America, so that most may be in transit when 

 seen in Panama, but winter records have gradually accrued, suggesting 

 that the species regularly winters in Panama, at least in small numbers. 



Geographic races in this species, widespread in its distribution in 

 the breeding season, are not always clearly evident. On their northern 

 breeding grounds 2 main groups may be recognized, one — in which the 

 forehead is white — that is mainly northern, and the other — with this 

 area chestnut-brown — found in the southern section. The distinction 

 of subspecies in those of typical markings is clearly evident, but in the 

 broad area where the two approach during the nesting season, the 

 colors mentioned merge through intergrades so completely that there 

 is no clear-cut division. As a whole, northern populations are larger, 

 but here again, there is intergradation. From the considerable series of 

 specimens available from Panama, 4 groups may be separated on the 

 basis of color and size. Their records of occurrence are listed under the 

 four headings that follow. (Two others that have been described are 

 not clearly separable.) 



While Cliff Swallows as a species may be identified readily in life, 

 the various forms are so similar that the race may not be determined 

 unless the bird is in the hand. Usually they are seen flying in company 

 with other swallows, most frequently with the more abundant Barn 

 Swallows. From available dates, the fall flight southward is recorded 

 in Panama from August 21 through September to October 6. J. Karr 

 and Ridgely (in litt.) saw 2 at Chiva Chiva, Canal Zone, on July 29, 

 1968. 



Winter records known to Ridgely (in litt.) include 1 at Tocumen, 

 with 50 Barn Swallows on January 29, 1973; 6 at Flamenco Island 

 (Fort Amador) on January 30, 1973; 2 at La Jagua on January 27, 

 1976; and from Chiriqui, 1 at Las Lajas on February 13, 1976. 



Spring migration evidently begins early. Ridgely and R. McArthur 

 saw 1 Cliff Swallow flying north over Panama Bay on February 12, 

 1970. In March and April this species can be as abundant as Barn 

 Swallows. On March 6, 1976, for example, Ridgely saw thousands 



