Concord, Mass.
1906
Aug. 25
  Brilliantly clear with light E. wind. Very cool at
morning & evening but warm in middle of day.
  About 200 Swallows appeared at Ball's Hill this
evening shortly after sunset. Judging by their voices all 
were Barn Swallows. For a time they skimmed back
and forth over the river and its bordering marshes
but they all kept close together and were evidently
not feeding. Indeed they behaved not unlike a large flock
of Peeps turning and wheeling abruptly as if at a signal
given by some accepted leader &, when pursuing a direct
course, moving very swiftly. At length they rose in 
a broad spiral sweep to a height of two or three
hundred feet and started off in a southerly direction
looking like an immense swarm of flies against the
bright light in the northern sky. For some time
after they had become lost to sight in the distance
I could still hear their voices but these finally
became inaudible. Five minutes later a small portion
of the flock - certainly not more than fifty birds - 
returned and swept down to the river where we
saw or heard them flying about until it was nearly
dark. What became of the remaining birds I cannot
say. It certainly looked as if they departed on
migration but it may have been a false start
like the one I witnessed at Lake Umbagog a few years
ago. But even if that were so do not such 
false starts indicate that the real one is made
at evening and that the birds migrate by night?
Barn Swallows start on migration (?) at evening