BLACKBURNIAN WARBLER. 233 
The Blackburnian Warbler is one of the rarest and most 
beautiful species of the genus, which from the rst to the 15th 
of May, or sometimes later, pays a transient visit to the Middle 
and Northern States, on its way to its remote boreal place of 
retirement for the breeding season. It is still more rarely seen 
in the autumn, about the month of September, in its passage 
to tropical America, where it winters, as may be presumed, from 
its occurrence late in autumn about Vera Cruz, according to 
Mr. Bullock. It is an exceedingly nimble insect-hunter, keep- 
ing towards the tops of trees, scarcely uttering even an audible 
chirp, and at this season no song as far as is yet known. 
On the Magdalene Islands in the Gulf of St. Lawrence, in 
June, Audubon remarks that he heard the song of this beauti- 
ful warbler, consisting of five or six loud notes, which it uttered 
from the branches of a fir-tree while engaged in quest of its 
prey. The nest found in Nova Scotia was made externally of 
coarse materials and lined with silky fibres and delicate strips 
of bark, over which lay a thick bed of feathers and horse-hair. 
It was found in a small fork of a tree, 5 or 6 feet from the 
ground, near a brook. Dr. Brewer also found a nest of this 
species in Massachusetts. 
The very rare adult of the Hemlock Warbler was found by 
Wilson in the Great Pine Swamp in Pennsylvania, and ap- 
peared to take up its residence in the dark hemlock-trees of 
that desolate region. It was very lively and active, climbing 
among the branches and hanging from the twigs like a Tit- 
mouse. It darted after flies to a considerable distance, and 
beginning with the lower branches, hunted with regularity up- 
wards to the summit of the tree, and in this way it proceeded 
very industriously to forage through the forest till satisfied. At 
intervals it stopped an instant to warble out a few low and 
sweet notes, probably for the recognition or company of its 
mate, which the discoverer, however, did not see. 
The nest of this species, according to Audubon, who discov- 
ered it in the Great Pine Swamp, was made in a hemlock or 
