This adult male "Brewster's Warbler" was apparently unpaired and by far the most vocal Vermivora warbler in this part of Stirling Forest. I've hardly ever seen a Brewster's, much less photographed one, so this was a special start to my day. Brewster's are Golden-winged X Blue-winged Warbler hybrids, and in fact may be back-crosses with Golden-winged. As hybrids they display quite a range of variation but they tend to be grayer, with little yellow but lacking the black throat and mask of Golden-winged. It's not difficult to see the Blue-winged heritage in this bird either.
While this is a spectacular bird its mere existence speaks to an ongoing micro-tragedy: that of the slow extirpation of Golden-winged Warbler in the NYC metro area because of the introgression of Blue-winged Warbler into the gene pool. In this competition the more numerous Blue-winged always seems to win (Lawrence's Warbler is the other side of the hybrid appearance spectrum). NJ now has no strongholds of Golden-winged Warbler, although Stirling Forest (NY) is still pretty good for Golden-winged. The nearby Old Mine Rd (NY) Golden-winged population appears primed to succumb to the local Blue-winged Warblers.
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