Be sure of your bird. You may want to check your field guide further before making your call. Greater Yellowlegs sometimes hustle about in an erratic, haphazard fashion. They are always wary, always watchful and quick to fly. The long legs are yellow.
Winter plumage is grayish.
Breast is finely streaked. Dark bill is pale at its base except in spring. A white rump patch is visible in flight. The yellow hue of the legs may vary to yellow-orange. The immature Greater Yellowlegs is browner and somewhat darker on wings and upper parts than winter adult.