BIRDS OF PENNSYLVANIA. 
253 
tind three or a less number deposited when incubation is be^un. 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 covered 
over the top as is the Cliff Swallow’s) of mud, grasses and feathers. The mud used 
to cover the exterior, and in fact make up the greater part of the nest, is collected 
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 mandible. 
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, or 
sometimes, but not usually, I think, retort-shaped or bottle-like in appearance, with 
the opening built out, often several inches from the body of the nest. The eggs are 
very similar in size to the 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 
Swallows. Its eggs are about the same size as those of the Rough-winged species. 
“ Primaries nine. Bill triangular, depressed, about as wide at base as long; the 
gape twice as long as culmen, reaching to about opposite the eyes ; tomia straight or 
gently curved ; no obvious rictal bristles. Tarsi not longer than the lateral toe and 
claw. Wings long and pointed, the first primary equal to or longer than second. 
Middle tail feathers not half as long as the wing.” 
Genus PROGNE Boie. 
Progne subis (Linn.). 
Purple Martin. 
Description {Plate 58). 
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 the male to attain his full dress. 
Habitat. — Temperate North America, south to Mexico. 
Common resident from early in April to about the middle of August; 
they arrive in spring, singly, in pairs or small flocks. Late in August 
