Date: 3/9/17 6:41 pm
From: Daniel Estabrooks <000000078b08fc2d-dmarc-request...>
Subject: [BRDBRAIN] Habitat Segregation in Yellow/Western Palm Warblers?
Hey BirdBrainers,
I've decided to focus this year on birding some of the large wilderness areas around Polk County that get very little birding attention. It gets a bit dull at times. (Some of these places are lightly birded for a reason. LOL) But I think I've discovered something interesting about Palm Warblers in the process...
(To clarify, i'm going to refer to the two Palm Warbler subspecies groups as "Western" and "Yellow" because that's what eBird calls them.)
I went back over my eBird reports from the last few years and discovered that, with very few exceptions, all the Palm Warblers I've seen in urban settings or in small nature preserves close to significant human development (Circle B Bar Reserve, Saddle Creek Park, etc.) have been Westerns. On the other hand, nearly all the Palms I've seen in large protected areas farther from human influence (Green Swamp Wilderness Preserve, Hilochee WMA, etc.) have been Yellows. And I often have to hike 2 miles or more into a particular preserve before I start seeing them.
So that makes me wonder... Are Western Palms more adapted to human disturbance than Yellows? Are Yellows better competitors and thus able to take over areas of more pristine habitat? And if so, could human development (or lack thereof) be a selection pressure that keeps the two taxa separate? I know the two types interbreed where their breeding ranges meet, but if disruptive selection is occurring such that the two extremes (what we know as Yellow & Western) are favored in different areas but intergrades are favored nowhere, then they could be diverging into separate species.
Anyway, I have literally no knowledge of what research has been done on Palm Warbler taxonomy/evolution, so for all I know, these questions could have all been answered and I just don't know it. I just thought it was interesting and wondered if anyone else has seen such a phenomenon or knows of any relevant research.
Daniel EstabrooksWinter Haven, FL

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