Monday, May 28, 2007

What is that yellow stuff on the Turkey Vultures faces?

See that stuff under the Turkey Vultures eye? To tell the truth the only Turkey Vulture I'd seen up close didn't have that and the other day when I watched a flock take off leaving one bird on the ground with a dead duck who was utterly unconcerned about my presence, I really wondered what was wrong with him. Did he have some kind of dread disease? Was he blind and that's why he seemed so unconcerned?
I perused the field guide, nobody looked like that.
Then yesterday there were a whole group of nine standing in a cornfield, just standing there, not eating, not doing a thing. I looked closely and they had the yellow gunk too. Is it an epidemic? Did the entire flock have it? I started panning.

No not everyone had a bad case. This guy looked even worse; he had black spots instead. Yeek!

When in doubt, contact a rehabber, which I did. The local rehabber, who wishes to remain anonymous, let me know that it was normal. Normal? But even if it doesn't look like pus, it looks warty or scrofulous. Yup, normal. No one knows whether it's genetic or what, or why this "adaptation" exists, but as most Turkey Vultures mature they get this change in the skin under their eyes. (The guy with the black spots is young. The "spots" are actually the black down that has been molting off a youngster.)
The Turkey Vulture, Cathartes aura, Latin for "cleansing breeze", who most humans don't find very pretty, has a great scientific name and a horde of marvelous adaptations but somehow even the adaptations are well--somehow unattractive to humans and they've had a very bad rep in the past.
For instance, they cool themselves by defecating on their feet. Quite handy actually but not something we'd like to try.
Then there is their job, the disposal of dead animals in a large territory by eating them. Yuck. But the Turkey Vulture, as I said has some marvelous adaptations that make it all work.
They've a special oil that is exuded from the skin on their heads so that none of their dinner sticks to it. Then the UV rays of the sun kill the bacteria on their skin. Wait, why would carrion stick anyway? One adaptation they don't have is any tearing equipment. (It's been discovered just lately that they aren't really raptors at all but flesh eating adapted storks, who knew?) No talons, no razor sharp beak, so if a meal has no breaks in the skin when they find it, they must stick their heads in an orifice and start from the inside out.
Vultures have often been accused of being disagreeable to each other. Turkey Vultures are not particularly disagreeable. When you see two, tugging with each other over a piece of flesh, they aren't being competitive they are helping each other tear swallow size bits off the big piece.
They're monogamous and mate for live which we tend to think is sweet. They will often use a nesting site year after year. Very homey. Unfortunately at that point it really begins to smell.
Speaking of smell, theirs is quite keen , particularly for carrion less than 24 hours old. They'd prefer to eat it within that time frame, but it doesn't always work out that way. Theirs is a kind of feast or famine kind of job therefore when there is food they pig out and when there's not they can last for sometime without eating.

Their digestion is iron clad and deals with toxins and bacteria so that what they excrete is quite clean compared to what goes in at the beginning.
They alert other members of the flock when they find food, which seems like a characteristic we'd find attractive--it's just the rest doesn't quite make up for it.
Though proved completely false, it's long been thought, and the thought is perpetuated by extermination companies to this day, that Turkey Vultures spread livestock disease. In actuality the exact opposite is true. They clean up diseased livestock and therefore the problem bacteria and therefore the disease, doesn't get a chance to spread.

Okay, if all is so normal why have all these Turkey Vultures just been standing in this field for hours?
Probably as they've most likely eaten recently and there aren't any thermals at the moment they are waiting for some to occur to help get them off the ground---so they wait. It's not like they're going to peak around for seeds or insects, they're not in the diet plan.
Eventually the earth will warm enough to create thermals. Then the birds will all jump in circling up higher and higher in stages. When they do that it's called a kettle, supposedly because it looked like boiling water to someone. And when they reach a height where they have enough elevation they'll disperse, floating along sniffing, looking for more food for the flock.
They truly are serving the public good. What if all that carrion just laid around? It would be far less attractive than we find them.
Donegal Browne

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