One of the great things about my trip to Fern Ridge Reservoir last weekend were all the Yellowlegs that I saw. The viewing platform area off from Royal Avenue had the highest concentrations. If they weren't nearby in a pond, they were flying over head.The other cool thing was the fact that there were both Greater and Lesser Yellowlegs mixed together which provided a great opportunity to compare the two species.
The upper two images are of a couple of Lessers that stuck together for the most part, while the bottom image shows them along with a Greater. You can easily see the difference in size and fact that the Greater's bill slopes up slightly while the Lesser's is relatively straight.
To me, there also seems to be something different about the heads. Greater's seem to have slightly longer necks and their heads seem to have more well defined features. It's subtle, but I can usually see it even when they aren't side by side.
