SENNETT ON BIRDS OF THE EIO GRANDE OF TEXAS. 15 



Tachycineta bicolor, (V.) Coues. — Wliite-hellied Swallow. 



Numbers were seen on our way down the coast from Indianola to 

 Point Isabel. They were also seen about the lagoons in the vicinity of 

 Brownsville up to about April 1st, after which time none were observed. 



Petrochelidon lunifrons, {Say) Cah. — Cliff Sicallow. 



None were seen lower down the river than Hidalgo, much to our won- 

 der, for the conditions seem quite as favorable for them at Brownsville 

 or Matamoras as at points above. In the absence of cliffs in the vicinity 

 of Hidalgo, they adapt themselves to the eaves of the buildings in the 

 town. Through the kindness of Sheriff Leo we occupied the court-house, 

 and these Swallows were incessantly working and chattering about us 

 from daylight until dark, and even iu the night we could hear them in 

 their nests. We had ample opportunity to observe their habits. They 

 are gregarious in all their occupations. In collecting mud for their 

 houses, the choice spots of their selection on the margin of the river are 

 so thickly covered with them that often more than a hundred will be 

 huddled on and over a space of two feet in diameter. The curious 

 bottle-shaped nests were crowded so thickly together that little could 

 be seen of them but tlieir mouths. We endeavored to obtain a sample 

 of the nests entire ; but there was so much quicksand in the mud of 

 which they were made that we found it impracticable to do so. None 

 of the nests were lined. In some we found stones and bits of broken 

 crockery, which, had been thrown in by the boys before the nests were 

 completed ; and yet the birds had laid their eggs among the rubbish. 

 In making the nest, the first choice is a corner formed by wall, eaves, 

 and rafter, very little labor, therefore, being necessary to make the re- 

 maining side. This side or nest is made spherical, with the mouth and 

 neck standing out some two inches from it. The next ones lap on to it, 

 others lap on to them, and so on. As soon as a shelf is formed large 

 enough to hold the bird, it sti»nds on it and works from within. The 

 pair work in turn. To gather the eggs it is necessary to demolish a part 

 of the nest, unless, as we sometimes found, eggs were laid before the 

 nest was finished. In the completed nests, the clutch varied from four 

 to seven ; but in one extra large nest, which from its size and shape 

 looked as if two birds occupied it in common, we took ten eggs. From 

 the window of our sleeping-room we could watch the birds at their work 

 without disturbing them, although but four feet distant from some of 

 them. When we took the eggs, on May 7th, some were nearly ready to 

 hatch, but most of them were fresh, and many birds were just beginning 

 their nests. 



The ground color of the eggs is a dull white. The markings are brown 

 and very variable. Some are speckled, others blotched; some regu- 

 larly over the whole egg, and others with far the greater number of 

 spots on the larger end. The longest egg was 0.90, the shortest 0.70; the 

 broadest 0.60, and the narrowest 0.53. The average of fifty eggs is 0.80 

 by 0.56. 



389— 5 —5.75 X 11.50 x 4.12 x 1.88. May 7, Hidalgo. 



