According to Mr. Audubon, it feeds largely upon spiders, which it obtains by turning over the withered leaves on the ground. The young birds resemble their mother until the following season, when the males attain the full beauty of their plumage. They remain with their parents until they migrate.
The late Dr. Alexander Gerhardt, an accurate and observing naturalist of Northern Georgia, informed me, by letter, that the nest of the Kentucky Warbler is usually built on the ground, under a tuft of grass, often on a hillside and always in dry places. The eggs are deposited from the 4th to the 15th of May. Nearly all the nests he met with were made externally of a loose aggregation of dry oak and chestnut leaves, so rudely thrown together as hardly to possess any coherence, and requiring to be sewed to be kept in place. The interior or inner nests were more compactly interwoven, usually composed of fine dark-brown roots. Instead of being small, they are large for the bird, and are inelegantly and clumsily made. They measure four inches in their diameter, three in height, and two in the depth of their cavity. One nest, the last received from Dr. Gerhardt, obtained by him at Varnell’s Station, in Northern Georgia, June 5, 1860, is large and peculiar in its construction. It is nearly spherical in shape, with an entrance partially on one side and nearly arched over. The periphery of this nest is composed exclusively of partially decayed deciduous leaves, impacted together, yet somewhat loosely. Within this outer covering is a fine framework of stems, twigs, and rootlets, and within this a snug, compact lining of hair and finer rootlets and fibres. This nest is six inches in diameter and five in height. It contained four eggs.
These eggs have an average length of .69 of an inch and a breadth of .56 of an inch. They have an oblong-oval shape, a crystalline-white ground, and the entire surface is sprinkled over with fine dots of red and reddish-brown. These, though most abundant about the larger end, are nowhere confluent, and do not form a crown.
A nest of this bird from Chester County, Penn., is a very flat structure, evidently built in a bed of fallen leaves. It has a diameter of six inches and a height of only two. The cup is a mere depression only half an inch in depth. Its base is loosely constructed of dried leaves, upon which is interwoven a coarse lining of long, dry, and wiry rootlets and stems of plants. It was given to Mr. J. P. Norris, from whom I received it, and it is now in the Boston collection.
Mr. Robert Ridgway furnishes the following valuable information in regard to the abundance and general habits of this species as observed in Southern Illinois: “It is a very common summer bird in Southern Illinois, where it arrives in the Wabash Valley towards the last of April. It is a wood-loving species, and of terrestrial habits, like the Seiurus aurocapillus, but generally frequents rather different situations from the latter bird, liking better the undergrowth of ‘bottom’ woods than that of dry forests. In all its manners it closely resembles the Seiuri, especially the two aquatic species, ludovicianus and noveboracensis, having the same tilting motion of the body, and horizontal attitude when perching, so characteristic of these birds. The nest I have never found, though well aware of its actual situation. I knew of one somewhere among the ‘top’ of a fallen tree, but it was so well concealed that the closest search did not enable me to discover it. In most cases the nest is probably on the ground, among the rubbish of fallen tree-tops, or low brushwood.
“The usual note of this Warbler is a sharp tship, almost precisely like that of the Pewee (Sayornis fuscus), uttered as the bird perches on a twig near the ground, continually tilting its body, or is changed into a sharp rapid twitter as one chases another through the thicket. Their song is very pretty, consisting of a fine whistle, delivered very much in the style of the Cardinal Grosbeak (Cardinalis virginianus), though finer in tone, and weaker.”
Dr. Coues found this Warbler rare at Washington, and chiefly in low woods with thick undergrowth, and in ravines. They were very silent, but not shy, and a few breed there.
Section GEOTHLYPEÆ.
Genus GEOTHLYPIS, Caban.
Trichas, Swainson, Zoöl. Journ. III, July, 1827, 167 (not of Gloger, March, 1827, equal to Criniger, Temm.).