I suspect this is an Eastern Crowned Warbler. The clean underparts, unmarked lower mandle, solid eyestripe and dark crwon all suggest this specie rather than Arctic Warbler. Author: brendank Time: 22/08/2010 22:58
I originally thought that as well. However I could not detect any central crown stripe through binoculars. I know this picture isn't too clear but I can't detect one in this picture. Perhaps though the crown was very faint on this bird.