10 BIRDS OF THE REPUBLIC OF PANAMA PART 4 



open lands, but they never seem to stray far from water. They seem to 

 wander rarely to the upland country. My only record there is of one 

 seen at a small lake near El Volcan, March 20, 1960. 



The nesting season appears to extend from January to June. A pair 

 taken over the Rio Chagres at Juan Mina, Canal Zone, December 14, 

 1955, while ranging attentively together, showed no development of the 

 sexual organs. Others in January at several localities were breeding 

 individuals. Grown young, recently from the nest, are common in June. 

 They nest in holes in snags and stubs, fallen or standing in the water, 

 sometimes in cavities made originally by woodpeckers. The usual lo- 

 cation is low but above flood level. In Gatun Lake they may use the 

 metal cans placed at the tops of channel markers. 



January 31, 1957, at Mandinga, San Bias, I found a nest placed in a 

 shallow cavity in the end of one of the pilings supporting an ancient 

 wharf in the sheltered bay, when the female swallow flew out as we 

 passed near in a dugout canoe. The bulky mass of grass and other 

 plant stems that filled the lower part of the cavity held a deep cup of 

 finer materials, lined with the white and gray contour feathers of 

 herons. The 4 eggs, about one-third incubated, were oval in form and 

 white in color, without markings. They measure 18.7 X 12.6, 19.0 X 12.6, 

 19.2x12.7, and 19.4x12.5 mm. A set of 2 in the British Museum 

 (Natural History) sent to Salvin and Godman, by F. Blancaneaux 

 from British Honduras, collected May 5, 1888, also are oval, and white 

 without gloss. They are slightly smaller, as they measure 17.7x13.1 

 and 18.0x13.4 mm. Russell (A. O. U. Mon. no. 1, 1964, p. 132) says 

 that Peck, in British Honduras, in addition to the usual cavities in 

 stumps standing in water, also found nests placed "in abandoned wood- 

 pecker holes in pine trees situated in very open areas of the lowland 

 pine ridges." 



Stomachs of a few examined were filled with remains of a variety of 

 small insects, including diptera, hymenoptera, coleoptera, and hemip- 

 tera (see also Ricklefs, Auk, 1971, pp. 635-657) . A female collected by 

 Strauch (Bull. Brit. Orn. Club, 1977, p. 64) weighed 6.4 g. 



At Juan Mina, in January, in evening when Barn and other swallows 

 were moving over the river to communal roosts in marshy areas, I 

 found 20 or so of the present species gathered by themselves to sleep 

 on a many-branched dead snag standing isolated in the river. 



The species is one of extensive range from southern Sonora and 

 southern Tamaulipas, Mexico, south along the coastal lowlands through 

 Central America to eastern Panama, where it is recorded east to the 

 mouth of the Rio Mandinga on Golfo de San Bias, western San Bias, 



