4 



BIRDS OF THE REPUBLIC OF PANAMA — PART 4 



been executed by the late Walter Weber, certain prominent taxa were 

 lacking. We were fortunate to have Guy Tudor to remedy the defi- 

 ciencies and also to render the color frontispiece. Finally, it should be 

 recognized that were it not for the vigorous support and warm en- 

 couragement of S. Dillon Ripley, this volume would never have been 

 completed. 



Storrs L. Olson 

 Smithsonian Institution 

 Washington, D. C. 

 April 1982 



Order PASSERIFORMES 

 Family HIRUNDINIDAE: Swallows, Golondrinas 



The swallow family, almost worldwide in its distribution, has 11 

 species found regularly in Panama. All are birds of active flight that 

 feed on insects captured mainly on the wing. Winter migrants from the 

 north include 6 kinds, one of them, the Rough-winged Swallow, also 

 represented by a local race that nests widely through the Isthmus. Two 

 others, less numerous, are recorded as visitors from South America 

 during the months of southern winter, one of them — the Blue-and- 

 white Swallow — also with a resident subspecies in the western high- 

 lands. The Southern Martin of southern South America is definitely 

 known from a single specimen record in eastern San Bias. The Cave 

 Swallow is reported only from a specimen of uncertain history. 



Migrant flocks of swallows during the months of northern winter 

 may include large numbers of a single kind, but it is usual to see 2 or 

 more species in mixed company, joined where insects are abundant 

 through this common source of food. While most common in the low- 

 lands, swallows may be found in open lands at any elevation. The north- 

 ern migrants, especially the Barn Swallow, most abundant in western 

 Panama, often gather at dusk in large groups to sleep in growths of 

 rushes in marshy areas or in sugarcane. Mixed with others of the 

 family, they range in companies through the day. The Brown-chested 

 Martin, a southern season migrant, late April to October, from Brazil 

 and Argentina, gathers at night to sleep in trees (at least in its breeding 

 range) in large assemblages. It appears that this species, now common, 

 may have extended its winter range to Panama within recent years, 

 as it was not reported by the early naturalists who made collections and 

 observations in its present isthmian range. 



