Friday, May 18, 2012

Eyes on a River

On my drive in to work I typically pass by 6 or so Osprey, Pandion haliaetus. They are usually perched in Cottonwood trees like sentinels guarding some secret of the River that I wish I knew.  I have noticed something about these birds recently, although their brown and white coloration is distinct, the color patterns don’t appear to be the same from bird to bird; just as all zebras have black and white stripes, no two zebra’s stripes are the same. So I got to wondering, can you identify an individual osprey by the color pattern of its feathers?
credit: SDGFP

Like any good researcher I googled, “osprey feather patterns”. I struck out. All I found were general descriptions of the overall color pattern and habits of this species. Determined, I tried another search but again the information was general. “Dark brown and white raptor that prey’s solely on fish.”Sure that there was a better answer out there, I decided to try Google’s cousin, Google Scholar, where true geeks go for answers. I typed in “Osprey Coloration Patterns” and, alas, a 1994 article titled, Field Identification of Individual Ospreys Using Head Marking Pattern from the Journal of Wildlife Management was at the top of the list.
credit: USFWS

Researchers in France were able to identify 39 birds based on the feather patterns on their heads and then observe these birds over several years without disturbing (banding or capturing)them. The scientists found color pattern variation to be most distinct on the top of the head, but overall feather patters were different between individuals too. So, like the zebra, all osprey may look the same, but if you look a little closer you can see they are different.

credit: USFWS
By Angela Feldmann

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