There is an interesting article in Science Daily , link below, which will be of interest to Quebec birders.
In Quebec we sit on the very edge of the northern range for Golden-winged Warblers. We also have a small but probably expanding population of Blue-winged Warblers, also extralimital in range, where they have met before we have hybrids. In Sibley’s ‘The North American Bird Guide’ the progeny of hybridization, including back-crosses, are well illustrated and distinctive and I can’t help but think that here is evolution taking place as we watch. The Science Daily article suggests that the Golden-winged Warbler should have elevated protected status to prevent it’s demise but why would we? As I see it we would just be conforming to our own narrow view of biodiversity when, what we actually have is biodiversity within two closely related species, perhaps they are supposed to interbreed and, if one of the parent species lacks genetic vigour to survive, it won’t, but two different species now known as Brewster’s Warbler and Lawrence’s Warbler will. Just a thought.
Below are three photos, not very good ones I admit but I tend to only use my own stuff. The first is a ‘pure’ Golden-winged Warbler taken in Panama. The second a ‘pure’ Blue-winged Warbler (male) from Quebec. The last is a Brewster’s Warbler, a backcross adult also from Quebec.