Thursday, April 28, 2011

Wading Into Controversy - The Great White Heron

It would be easy for the casual observer to dismiss a tall white wading bird in Florida as a Great Egret (Ardea alba-top photo). The long, black-legged wader has a slim frame, thin beak and is found in a variety of shallow wetlands around the state. But in the fringes of southern Florida, every all-white wading bird requires a second look. It might be a Great Blue Heron (Ardea herodia-bottom left).
I took a walk in the 10,000 Islands National Wildlife Refuge recently. Located just east of Naples and north of the Florida Keys, the refuge is part of the second largest mangrove forest in the world. On this sweltering March morning, a volunteer welcomes me and suggests I may not see much on the boardwalk since most of the water has dried up. I step on the path, round the corner and standing before me is a Great White Heron (bottom right), a rare color morph of the Great Blue Heron. This all white heron is larger than the Great Egret, has a heavier bill and sports light colored or yellowish legs.
The Great White Heron population is estimated to be around one thousand and most of them live on and around the Florida Keys and mangrove islands. The debate that I will not settle for you has been their taxonomic classification. For years they were considered a distinct species (Ardea occidentalis), geographically isolated from the Great Blue Herons of the mainland. They have also been considered a subspecies with the ability to interbreed with Great Blue Herons but do not do so naturally due to geography. Or do they?
Great White Herons do migrate up to the southern peninsula of Florida but mainland Great Blue Herons rarely migrate down to the keys. The Great Blue Herons and Great White Herons that live in the keys are larger than their relatives to the north. When they do form mating pairs it is often with a color morph similar to their own.
The Great White Heron probably does not merit species status. It could very well deserve a subspecies distinction. I’ll leave that to the taxonomists, but it certainly warrants a second look.

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