Archibuteo lagopus
1875.
(Nov. 22) [November 22, 1875] which it invariably returned. The
appearance of these three birds handing
suspended in the air at the height of
about 50 ft. [feet] all within a radius of
100 yds. [yards] and for many minutes without
a single movement was very very
interesting. Sometimes when the wind
came in gusts, they seemed to have
some difficulty in preserving their
equilibrium and flapped their wings
rapidly at frequent intervals, but
in every event their exact place was 
maintained to an inch. Their descent
on their prey was made (as described
on p. 132 journal of 1873) in 'cycloid' [helical?][!] 
curves. At times all three would rise
to an immense height in the air
and sail in company. This sailing
was performed with extraordinary
ease and grace and the appearance
of the bird and the position of the
wings was very nearly like that of
Cathartes aura. Heard no cry or note
of any kind. The [They] frequently lit on the
ground usually on the top of some
elevated knoll. Walked over to the
sand hills behind Woodbury's where
I shot a single [male] Plec. nivalis [Plectrophenax nivalis]: saw
only one or two others of that species
and perhaps as many E. cornuta [Eremophila cornuta].
Where the small birds were I cannot
imagine, as we looked everywhere
for them. Saw a few Mergns serrator [Merganser serrator] &
great numbers of gulls including several
L. marinus [Larus marinus]. Reached home by 8 P.M.