5

Concord, Mass.
1916
April 4
to
July 9

  Bird migration was less hampered or delayed than
might have been expected, by the exceptional conditions which
so retarded vegetation through April and May. It its [is] true
that there were no really heavy flights of north-bound
migrants in April and only two such in May - on the 
2nd [May 2, 1916] and 20th [May 20, 1916], the latter being a typical "Warbler day".
This, however, is what commonly happens during springs
unaccompanied by extreme variations of temperature, when
birds migrating northward may come and go from day to
day without attracting much attention, because never
numerously assembled at any one time or place. They
seldom appear anywhere in excessive numbers except
when their advance is abruptly checked by sudden cold
or unduly hastened by correspondingly unseasonable heat.
Then they may literally flood our New England woods &
fields for a day or two before and after which few if any