Concord, Mass.
1909
May 25
(no 2)
  In the afternoon Purdie and I went to
Concord hoping to find a lot of interesting migrants
congregated along the river front at Ball's Hill where
they usually collect in great numbers when a heavy flight
is checked by a cold north wind from which the
hill shelters them perfectly. We were disappointed
in this expectation, however, for when we reached the
cabin about six o'clock there were only a few
birds of summer resident species there. On Pine Ridge
I saw a Black and Yellow Warbler & heard a Blackburnian.
These two were literally the only northern forms noted
and it is not improbable that the Blackburnian was
settled for the summer in the pines where we found him.
No signs of any unusual flight at Ball's Hill
  Every afternoon at this season, when there is a cold
northerly or easterly wind, Ball's Hill is a favorite resort of
Chimney Swifts. There were fully one hundred there at six
o'clock this evening, and for an hour later, careening about
the west end of the hill just above the tops of the oaks
which were covered with young foliage. I have not seen as
many before since the summer of 1903 when the Swifts,
like the Swallows, suffered heavy losses during the
cold rain storm which occurred in June of that year.
For two or three years after that they were very scarce
but during the past two years they have been increasing
rapidly. It is possible, of course, that the birds seen
this evening were migrants, but more probable, in my opinion,
that they represented the Swift population of the more
eastern parts of Concord.
Big swarm of Swifts at Ball's Hill