Brewster's Warbler (Blue-winged x Golden-winged Warbler Hybrid) - Ferry Road, Montague, Franklin Co., MA. May 13th, 2011. This super bird was found by Brian Kane on May 12th and still present this morning. It was giving a Blue-winged Warbler alternate song and showed very well right above Ferry Road, even singing from the overhead cables at times. This bird most closely resembled the 1st generation male Brewster's illustrated on P.428 of the Sibley Guide. However, the mantle tone is grayer (closer to Golden-winged) and the wing bars whiter (closer to Blue-winged) than Sibley's illustration which may point towards this one being a backcross variant rather than the offspring of pure parents. Either way, a really interesting bird for me having not seen anything like it since a backcross Brewster's in Veracruz, Mexico in October 2001.