The Birds’ Calendar 
yellow on the top of the head. It became very 
abundant, and I occasionally heard its music, 
which, if it be its full song, is hardly distin- 
guishable from the vigorous note of the red- 
start. It often happens that the migrants are 
not heard in full song while on their travels, so 
that one who meets them only during that period 
is unable to judge adequately of their vocal 
power. 
The altitude of the ‘‘ chestnut-sided’’ from 
the ground is greater than that of most of the 
warblers, being often found among the topmost 
branches of tall trees, like the yellow-rumps— 
suggesting the remark that in the case of most 
birds it is quite as necessary to know the mark- 
ings on the under side of the body as those on 
the back, as they are habitually found higher 
than one’s head. In general the characteristic 
marks are on the head (top and side), throat, 
and breast. 
The knowledge one can gain of any bird 
during May is necessarily meagre, as all the facts 
pertaining to nidification, and very often an 
acquaintance with their songs, must be gathered 
at another time. But during the month one 
can obtain in the Ramble—and in all other 
favorable localities—at least an intelligent and 
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