Concord, Mass.
1900.
May 8
  Cloudy with fresh S. W. wind and occasional
light showers. Ther. 37 degrees - 62 degrees (60 degrees at 7 P.M.).
(Ball's Hill)
  Upwards of 100 small birds spent the day on
the northern slopes of Ball's Hill and in the thickets
at its northern & eastern base. No doubt many of these
were attracted there partly because of the shelter from
the strong wind which this high, steep ridge affords &
partly by the swarms of gnats which had collected there 
for the same region. But after making due allowance
for these considerations it is evident that a heavy
flight of migrants arrived from the South during the
past night. It is interesting that such a flight took
place for the reason that it reached here in advance
of the warm wave which is beginning this evening.
Most of the birds above mentioned were Warblers of
the following species: Mniotilta varia (about 20), Hal.
rubricapilla (3 or 4) Compsothlypis a. usneae (3 or 4), Dendroica
coronata (about 40 mostly female female), D. pennsylvanica (about 20
all male male), D. virens (3 or 4 male male), D. caerulescens 1 male, D. p.
hypochrysea (2), Setophaga ruticilla (about 9 ad. male male & one
bird in plumage of female), Geothlypis trichas (5 male male), Vireo
olivaceus (1), V. flavifrons (1 singing), Carpodacus purpureus
(1 singing), Zonotrichia albicollis (1 im) Empidonax minimus
(2, another at Davis's Hill), Habia ludoviciana (male in full
song at 7 A.M.). In addition to these woodland birds
fully 100 Swifts & varying numbers of Swallows were 
darting about just above the tops of the trees.
Large numbers
of small birds
arrive just in
advance of a
warm wave.
  The gnats of which they were all feeding were those
small dark-colored ones which so closely resemble
the black fly of the north but which do not bite so
Swifts &
Swallows.
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