The Birds’ Calendar 
in all places, the spring observations are al- 
ways likely to be considerably in excess of 
those in fall. As before remarked, a few spe- 
cies seem to take a more inland route in one 
direction than in the other, and among those 
that follow the same route at both seasons there 
seems to be more lingering by the way in 
spring. 
Still another difference, making the identifi- 
cation of species far more difficult in fall, is the 
intermixture of the young on their first journey 
southward, in their immature and somewhat in- 
determinate plumage. In some cases the males 
do not attain ‘‘ full dress ’’ until the third year, 
and probably never until the second, and in 
the process of development the young of both 
sexes strongly resemble the less characteristical- 
ly marked female. 
Again, besides being more easily observed in 
the leafless shrubbery and trees of spring, they 
are more approachable at that season than at 
any other time. The white-throated sparrow, 
so shy in summer as often to elude the most 
careful search, and revealing itself only by its 
song, is very unsuspicious in the spring. The 
instinct of all animals impels them to be espe- 
cially on their guard during the season when 
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