BLUE-GRAY GNATCATCHER. 
171 
of a forest tree. It is formed of slight materials, such as the 
scales of buds, stems and parts of fallen leaves, withered blos- 
soms, fern down, and the silky fibres of various plants, lined 
with a few horsehairs, and coated externally with lichens, in 
this frail nest the Cow Troopial sometimes deposits her egg, and 
leaves her offspring to the care of these affectionate and pigmy 
nurses. In this case, as with the Cuckoo in the nest of the 
Yellow Wren and that of the Red- tailed Warbler, the egg is 
probably conveyed by the parent, and placed in this small and 
slender cradle, which would not be able to sustain the weight 
or receive the body of the intruder. 
Though classed with the Flycatchers by Nuttall and other writers 
of his day, this species is now ranked as one of the highest types of 
the Oscines, or Singing Birds, and a sub-family has been made for 
this and the two W^estern forms. Mr. William Saunders finds the 
present species fairly common near London, Ontario, but it is only 
casual in Massachusetts, and is rarely seen north of latitude 42°. 
It winters in the Gulf States and southward. 
