The eggs vary from four to six in number, and also differ greatly in their size, so much so that the question has arisen if there are not two species, closely resembling, but differing chiefly in their size. Of this, however, there is no evidence other than in these marked variations in the eggs.
In the Great Basin, Mr. Ridgway found this bird abundant in all the bushy localities in the vicinity of water, but it was confined to the lower portions, never being seen high up on the mountains, nor even in the lower portions of the mountain cañons.
Their eggs exhibit a variation in length of from .55 to .72 of an inch, and in breadth from .48 to .58 of an inch; the smallest being from Georgia, and the largest from Kansas. They are of a beautiful clear crystalline-white ground, and are dotted, blotched, and marbled around the larger end with purple, reddish-brown, and dark umber.
Geothlypis philadelphia, Baird.
MOURNING WARBLER.
Sylvia philadelphia, Wils. Am. Orn. II, 1810, 101, pl. xiv; Aud.; Nutt. Trichas philadelphia, Jard.—Reinhardt, Vidensk. Meddel. for 1853, and Ibis, 1861, 6 (Greenland). Geothlypis phila. Baird, Birds N. Am. 1858, 243, pl. lxxix, fig. 3; Rev. 226.—Sclater, Catal. 1861, 27 (Orizaba).—Lawrence, Ann. N. Y. Lyc. 1861, 322 (Panama).—Samuels, 207.—Dresser, Ibis, 1865, 476.
Figures: Wils. Am. Orn. II, pl. xiv.—Aud. Birds Am. II, pl. ci.
Sp. Char. Wings but little longer than the tail, reaching but little beyond its base. Adult male. Head and neck all round, with throat and forepart of breast, ash-gray, paler beneath. The feathers of the chin, throat, and fore breast in reality black, but with narrow ashy margins more or less concealing the black, except on the breast. Lores and region round the eye dusky, without any trace of a pale ring. Upper parts and sides of the body clear olive-green; the under parts bright yellow. Tail-feathers uniform olive; first primary, with the outer half of the outer web, nearly white. Female with the gray of the crown glossed with olive; the chin and throat paler centrally, and tinged with fulvous; a dull whitish ring round the eye. Length, 5.50; wing, 2.45; tail, 2.25. Young not seen.
Hab. Eastern Province of United States to British America; Greenland; Southeastern Mexico, Panama R. R., and Colombia. Not recorded from West Indies or Guatemala. Costa Rica (Lawr.).
Specimens vary in the amount of black on the jugulum, and the purity of the ash of the throat. The species is often confounded with Oporornis agilis, to which the resemblance is quite close. They may, however, be distinguished by the much longer and more pointed wings, and more even tail, shorter legs, etc., of agilis. The white ring round the eye in the female philadelphia increases the difficulty of separation.