February 
investigation after an unusually vernal day (and 
especially after one or two warm and cloudy 
nights), one is likely to find fresh accessions to 
such species as had already appeared, as well 
as forerunners of new species. Thus, while it 
may be true that none of the zadviduals re- 
main more than a few days in a place, replen- 
ishment will keep a sfeczes represented in a 
given locality for many weeks, which is most 
fortunate for the student. 
The fall migrations are less favorable for ob- 
servations, not only for reasons already given, 
but for others to be cited hereafter, so that we 
must rely chiefly upon our opportunities in 
April and May for learning what we can of the 
‘‘migrants.’’ Without special attention given 
to the subject during this period, one will never 
make the acquaintance of some of the most 
beautiful and rare specimens, and some of the 
finest singers as well. 
The migratory movement of birds begins, for 
this latitude, sometimes as early as the middle 
of February, when the song sparrows begin to 
appear, and the snow-birds considerably increase 
in number, and continues until a little into June. 
One of the last migrants to disappear is the 
olive-backed thrush, which I saw June 2d; and 
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