THE INVITATION 207 
pairs, and their black caps and striped coats show 
conspicuously. When they return in September 
they are in troops or loose flocks, are of a uniform 
dull drab or brindlish color, and are very fat. They 
scour the treetops for a few days, almost eluding 
the eye by their quick movements, and are gone. 
According to my own observation, the number of 
species of warblers which one living in the middle 
districts sees, on their return in the fall, is very 
small compared with the number he may observe 
migrating north in the spring. 
The yellow-rumped warblers are the most notice- 
able of all in the autumn. They come about the 
streets and garden, and seem especially drawn to 
dry, leafless trees. They dart spitefully about, 
uttering a sharp chirp. In Washington I have seen 
them in the outskirts all winter. 
Audubon figures and describes over forty differ- 
ent warblers. More recent writers have divided 
and subdivided the group very much, giving new 
names to new classifications. But this part is of 
interest and value only to the professional orni- 
thologist. 
The finest songster among the Sylvia, according 
to my notions, is the black-throated greenback. 
Its song is sweet and clear, but brief. 
The rarest of the species are Swainson’s warbler, 
said to be disappearing; the cerulean warbler, said 
to be abundant about Niagara; and the mourning 
ground warbler, which I have found breeding about 
the head-waters of the Delaware, in New York. 
