444 
BIRDS OF PENNSYLVANIA. 
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very different, however, in Butler and Armstrong counties. There every patch of 
hazel thicket has its pair of Chestnut-sided Warblers, or, if extensive, its several 
pairs, the gay and sprightly male ever prominent on its outskirts or on some shrub 
in its midst, constantly uttering his short but sweetly modulated song, while in its 
more secluded haunts his less gaudily-attired mate is faithfully guarding her fragile 
treasures. Notwithstanding this clue, their nests are hard to find ; after many vain 
searches I at last succeeded in finding one (June 3, 1889) containing four highly 
incubated eggs. It was built in a crotch of a hazel stalk about four and one-half feet 
from the ground. The eggs were an extremely light shade of greenish-white, 
spotted with reddish-brown and the usual lilac shell-markings, especially about the 
larger end. The nest was composed of grasses, weed-stalks, bark-strips and glisten¬ 
ing fiber from the milk-weed plant, lined with horsehair and fine wiry weed-stalks. 
It was a noticeable fact that this warbler was found only on the high dry ground.” 
Dendroica virens. Black-throated Green Warbier (289). Abundantasa migrant 
in Beaver county, but in Butler and Armstrong counties a common summer resident, 
being found in rich coniferous woods, where its peculiar filing notes were constantly 
heard. No nests were found, but I observed it continually until my departure on 
June 14. ( Dendroica ccerulescens , whose range is known to be otherwise coincident 
with that of virens , will doubtless also be found nesting here in time ) 
Geothlypis formosa. Kentucky Warbler (271, 296, 297). Rare summer resident 
in Beaver county. 
Geothlypis Philadelphia. Mourning Warbler (271, 297). “ Two specimens have 
been taken thus far, one on May 11, 1889, and the other on May 21, 1890, which dates, 
though in different years, probably represented the extremes of the migratory 
movement at this place.” 
Icteria virens. Yellow-breasted Chat (271, 299). A common summer resident 
in Beaver county, the country being apparently well-adapted to its needs. I did not 
meet with it in Butler and Armstrong counties. Its arrival occurs during the lastof 
April or first of May, and by the end of the latter month or early in June nests with 
eggs are to be found. 
Sylvania mitrata. Hooded Warbler (271, 300). “Two individuals of this rare 
Warbler were seen in migration September 13, 1890, one of which was secured, and 
another was noticed on the 25th.” 
Sylvania canadensis. Canadian Warbler (271, 301). A common migrant in 
'Beaver county, but in Butler and Armstrong counties a common summer resident, 
breeding in thickets in low damp places, preferably in woods along the banks of 
streams, where its pretty song is constantly heard. 
Polioptila ccerulea. Blue-gray Gnatcatcher (323, 324). “In Beaver county this 
species is a common summer resident, but in Butler and Armstrong counties it is 
conspicuous by its absence. They begin to build immediately upon their arrival 
about April 18, their nests being readily found by watching the parent birds. * * * 
The eggs, usually five in number, are very small and delicate; a pale green color 
dotted with well-defined small brown spots, which tend to aggregate at the larger 
end.” 
Tardus fuscescens. Wilson’s Thrush (325) This bird has heretofore been con¬ 
sidered to be a transient visitor in Pennsylvania, breeding but very rarely, and then 
chiefly in mountainous districts, but in Butler and Armstrong counties I found it 
to be a common breeder. Referring to a nest with eggs of this bird found in Butler 
.county, May 27, 1889, by Mr. James Myers and Mr. Todd, the gentleman last named 
writes in substance as follows : The bird was flushed from her nest, which was 
built on the ground in a high woods with a thick undergrowth of laurel and huckle¬ 
berry. The nest, composed of leaves, strips of bark and weed stalks, with broken 
leaves as a lining, was placed on a mound of leaves, surrounded and canopied over 
with huckleberry bushes. Measurements: diameter, outside, 5 inches; depth, 4 
inches ; cavity, 2f by 2? inches. Three eggs, slightly incubated, same shade of 
bluish-green as Wood Thrush ( Tardus mustelinus ), but of course smaller. 
