204 BIRDS OF PENNSYLVANIA. 



water's surface. In clear weather these birds often ascend to high elevations in the 

 air, but in dull weather, particularly before rains, they fly low and sail close to the 

 ground. With the exception of two species, all our swallows lay pure white and 

 unspotted eggs. The eggs of these two species, the Cliff and Barn Swallows are 

 white, speckled or spotted with reddish brown, and so alike are the eggs of these 

 two birds, that they cannot with absolute certainty be distinguished apart. The usual 

 complement of eggs of each of our species is five, sometimes six, but very seldom 

 do we find three or a less number deposited when incubation is begun. The Purple 

 Martin builds a nest of hay, straw, leaves, feathers, etc., in boxes provided for them 

 about houses and buildings, occasionally with us this species breeds in holes in trees. 

 Its eggs average a little under one inch in length, and about three-fourths, or a little 

 less in width. The Barn Swallow nests mostly in the interior of barns, where on a 

 beam or rafter, near the top of the roof, it builds a large bowl-shaped nest (not cov- 

 ered over the top as is the Cliff Swallows) of mud, grasses and feathers. The mud 

 used to cover the exterior, and in fact make up the greater part of the nest, is col- 

 lected by the birds, along the edges of streams, ponds and in muddy places in fields 

 and roads, and conveyed in small rounded masses on the top of the upper bill. The 

 eggs measure about .77 long by. 55 of an inch wide. The Cliff Swallow with us nests 

 under the eaves of barns and other out-buildings. It never, I think in this State> 

 breeds about rocks or cliffs, as it does in uninhabited regions. The nest is built of 

 small mud pellets, warmly lined with feathers, or other soft materials, and in this 

 region is hemispherical in shape, with a small hole in front or on the side. The 

 nest of this bird is usually described in books as being retort-shaped or bottle-like in 

 appearance, with the opening built out, often several inches from the body of the 

 nest. I have examined many nests of these birds found in Pennsylvania, but have 

 never yet seen one, which could be called retort-shaped or bottle-like. The eggs are 

 very similar in size to those of the Barn Swallow, from which they are said to differ 

 in being less elongated. The Bank and Rough-winged Swallows excavate holes in 

 sand banks, along streams, deep railroad cuts, wagon roads, etc., in which they 

 build loosely made nests of grasses and feathers. The Rough-winged, with us breeds 

 usually in the interstices of stone abutments of bridges or in the holes of old stone 

 barns or similar structures. The eggs of this last named species are possibly a trifle 

 larger than those of the Bank Swallow, which measure about .70 long and about .50 

 of an inch in width. The Tree Swallow builds in holes of trees and stumps, or in 

 bird boxes. The nest is similar to those made by Bank and Rough-winged Swal- 

 lows. Its eggs are about the same size as those of the Rough-winged species. 



GENUS PROGNE. BOIB. 

 611. Progne subis (LINN.). 



Purple Martin. 



DESCRIPTION. 



Length 8 ; extent 16 inches ; bill black, mouth inside yellow ; eyes brown ; legs 

 dark brown ; closed wings, extend beyond the tail which is decidedly forked. Adult 

 male. Glossy blue black ; wings and tail feathers above black, more or less glossed 

 with blue-black ; under portions of wings and tail feathers dark brown. Adult 

 female. Dull brown above, glossed with blue black, brightest on back of head and 

 middle of back ; loral spaces and auricular, feathers dark brown or black ; forehead, 

 and narrow stripe about hind-neck, grayish white ; belly and under tail coverts 

 white ; rest of under parts dull grayish white, darkest on the sides. Young. Both 

 sexes quite similar to female, though the males are mostly darker. Immature 

 males, with blue black feathers singly or in patches, are common. About three 

 years, it is believed, are required for th-e male to attain his full dress. 



Hab. Temperate North America, south to Mexico. 



