LESSER & GREATER YELLOWLEGS, PARKER RIVER NATIONAL WILDLIFE REFUGE,PLUM ISLAND,MA, 8/26/18

   The Yellowlegs in these photos seem to be a mixture of Greater Yellowlegs and Lesser Yellowlegs, in breeding and nonbreeding plumage.  This is the time of year (August & September) when Yellowlegs molt from breeding to nonbreeding plumage.
   The Yellowlegs with the slightly longer and slightly upturned bills are most likely Greater Yellowlegs and the ones with shorter, straight bills are most likely Lesser Yellowlegs.  You can really only make this comparison when they are in profile.  The Yellowlegs with no or little barring on the flanks are probably in nonbreeding plumage, while the ones with more barring are probably in breeding plumage.
    The ID of which Yellowlegs is which is very subjective and I leave it up to the reader to decide.