I think there are 5 White-rumped Sandipers in this image of a small part of a flock of about 10,000 "peeps"- mostly Semipalmated. Grand Pre, Nova Scotia last weekend.
D300, 300 F/4 AF-S + TC-17E2, ISO 800, 1/800, F/8.0
Interesting exercise to try and find them all, Richard. Having trouble finding anything critically sharp - plane of focus seems behind the birds lower in the frame. I find the D300 AF too slow to be reliable for BIF when using an f4 lens + 1.7x and suspect that this may be part of the problem. Must have been an impressive sight with all those birds in the air.
I like that the frame is well-filled with birds and the focus seems to be somewhere in the middle of the flock. I think there is a brownish color cast.