[mou] Notes on Buff-breasted Sandpipers Thursday - Dakota Count (Long)

[Alt, Mark]

Yesterday morning (Thursday) at Jirik Sod Farms in Farmington, Dakota
County, Peter Neubeck and I watched flocks of Buff-breasted Sandpipers
forage and fly. The birds were viewed from 7:00 AM until 9 AM, during
which time they restricted their movements to the fields east of Blaine
Avenue, south of 200th. They seemed to use almost all of the fields in
that time, and were seen in small flocks of 4, 10, 12 and 20, and large
flocks of 52 and 72. It is assumed the total birds seen did not exceed
72. The birds walk briskly, almost choppily, with their heads pecking
forward sharply with each step taken, like a barnyard chicken. They are
easily distinguished by their movements from Killdeer who are in the
field in larger numbers, as well. When a bird dips to the right or left
to pick up some food, the white rump and flanks flash brightly. The BNA
reports up to 90% of their prey is made up of beetles and flies, both
adults and larvae, and these birds cover a lot of ground in getting fed.
I feel this is why they choose such expansive tracts of grass fields and
cover them so well; these birds moved about every ten minutes, and never
seemed to forage in the same area twice. The foraging behavior of the
birds when in small flocks differed slightly from what we observed in
the large groups. Twice, when in small flocks, the Buff-breasted
Sandpipers formed a skirmish line moving in one direction, dipping like
a plover to feed every ten steps or so. The birds were about 5-10 feet
apart and maintained their spacing. The moved fairly quickly in this
manner, at about the pace of a pheasant walking normally. When in the
large groups, the birds spaced themselves farther apart, from 15 to 30
feet, and moved within their space as though it was a feeding territory.
They appeared to cover less area in the large groups as individuals, but
wheeled right and left to cover their feeding "territory", then lifting
off to another part of the field. There was high variability in flock
size, little integrity being maintained within groups, and each flock
seen produced a different count. When they took flight, they stayed very
tight and low to the ground, appearing alternately dark and light as
they turned to show their backs and then their white bellies. No vocals
were heard at all and it was a good day for listening, with us being
close for much of the time. I read where these birds roost communally in
winter in Argentina, perhaps they do so en rout as well?

Mark Alt
Brooklyn Center
Hennepin County