Thursday, August 19, 2010

Vultures on the Barn

Turkey vultures can have a wingspan up to six feet.
Their wings usually appear two-toned from below.
One of the cats made a staccato sound on a hot day when I had all the window blinds closed.  Not understanding the predator's code, I looked around.  With their butts in the air, both Cole and Mango were straining to look under the living room blind.

I peered between their alert ears expecting to see a brown towhee on the windowsill or one of the spotted fawns draining the birdbath again.  Nothing moving in the backyard.  When I flipped open a blind slat, I startled a turkey vulture (Cathartes aura) on the garage roof directly outside the window.  As it dropped behind the roof line, I caught a brief glimpse of something hanging from its beak, round with a stem hanging down.  A leaf?  Or perhaps a mouse.  That explained the cats' complaint at seeing a scavenger steal their snack.

 
When people see vultures circling overhead, someone usually makes a joke about a companion's sickly or deathly appearance.  Our emotional response is more uneasy when we see vultures up close and down to our earth.  Vultures hunched together in a tree or gathering on the side of a road remind us of their ominous habit of eating the dead.
 Vultures spread their feathers like fingers to reduce wingtip turbulence and lower their stalling speed
so they can stay aloft at a lower speed (Ehrlich et al.)
At the Dipper Ranch, I frequently see vultures flying overhead.  The upper slopes of the ranch form a tipped-up grassy bowl that catches and swirls the breezes from the Pacific Ocean making for interesting air.  It's a good day when I get to watch the vultures freewheel over the ridgelines or slowly cycle up a thermal.  They are like dusty boys dreamflying in the sky with nothing more important or pleasant to do.  When the air is hot and still, they drop out of the sky and light onto high points like the tall transmission towers crossing Page Mill Road.  There they preen and watch the world below until a breeze picks up and the air has enough substance to lift them back up into the sky.  Less often, I see vultures scavenging a carcass, but in these wild mountains, that seems normal and businesslike, a cleanup service they provide for the natural world.


I had never seen a vulture on the garage before, so I headed outside to investigate.  I was surprised to find seven vultures on the barn.  What was going on?


On summer afternoons when I am working in the farmyard, I often see large shadows circling my project and then I know the local vulture gang is coming in for a drink.  First, they reconnoiter from on high.  Then, if I and the cows are a safe distance away, they descend in lazy loops to land in the corral, and hop across the grass and up onto the metal lip of the watering trough. A few are skilled enough to tap down onto the nearby barbwire fence and drop directly onto the trough.  Then commences 15 minutes of silent jostling for position, much wing flapping, and dipping of their scrawny necks into the water.  Eventually, each turns its naked head downhill, pauses as if to say a post-drink grace, and in ones and twos they leap off the trough with air-hungry wings to barely clear the barbwire fence on the opposite side of the corral and glide down Peter's Creek canyon.

Why were the vultures on the barn?  Was there a carcass nearby or had a lax breeze dumped them on the rooftops?  Oddly that morning, I hadn't seen the L11 doe or her two fawns on their regular routine to scarf down one of their favorite summertime victuals - the brown leaves dropped in the yard by the summer-deciduous buckeye trees.  I started searching the farmyard for a dead body.  My searching made the vultures nervous.  Soon they spread their wings to test for a breeze and clumsily flapped a short distance to the fence posts along the driveway.

Up close, the adult turkey vulture's plumage is black with brown iridescent tones.
The adult turkey vulture's head is red and its bill is yellowish.  They have a feathery black ruff on their neck.  Vultures' heads are bare of feathers to avoid getting too messy when they scavenge inside a rotten carcass.
I slowly made my way that direction to check the slope for a carcass.  The black-brown brethren seemed surprised to see me quietly appear among them.  They were all lined up which gave me an excellent chance to compare the different features of the adults versus the juveniles.

Juvenile turkey vultures have white edges on their feathers.
Juvenile turkey vultures still have grey down feathers on their head and their bills are also grey.
Sometimes, I thought I caught the faintest waft of a sweet-sour smell but it was probably just my vulture-induced imagination.  There was a flattened path in the grass above the orchard that I hadn't noticed before.  Was it a pathway trampled by the cattle?  Or did a mountain lion drag a doe down the hill?  Perhaps, with the juveniles recently fledged (turkey vultures take 104 to 129 days from egg laying to flight from the nest), the vulture clan was regrouping before they organized for migration.  Actually, I don't even know whether turkey vultures in the Santa Cruz Mountains are residents or if they migrate.

Even though I often stand still with swaying binoculars or even lie down on the ground to watch their mesmerizing flight, I'm sure the local vultures see me hiking across the ranch often enough to know that I am not dead.  For now, in absence of a carcass, I have decided the vultures have become accustomed to me watching them, a vulture groupie, and they just want to hang out.

This vulture quest to continue over the next week or so with:  Vultures and Migration, A Black Florida Vulture Adventure, and Vultures and Death.

Barn-stomping vultures
See also:

Hawks in Flight, Pete Dunne, David Sibley and Clay Sutton.

The Birder's Handbook:  A Field Guide to the Natural History of North American Birds, Paul R. Ehrlich, David S. Dobkin and Darryl Wheye.

The Turkey Vulture Society

This post is featured on #133 edition of I and the Bird along with many other great bird posts as part of the Nature Blog Network.

6 comments:

  1. Hi Cindy - I LOVE what you've done with your site! Your background image is beautiful!

    Nice action shot of the turkey vulture. I rarely see any angle but the direct-overhead view as they soar in lazy circles.

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  2. Thanks, Amber. Blogspot just introduced a whole new slew of templates just after I took a blogging class, so this was what I settled on.

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  3. Beautiful photo. We have a lot of those around lately. I think they may be migrating.
    Suzanne

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  4. Suzanne: where do you live? I am reading a lot about vulture migrations and it is different in different parts of the world. Now i am fascinated. I should be posting on that soon.

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  5. Great pictures and writing (like "clean up service for the natural world")! Think your theory they moved to barn from the dying roost tree may be right. Vultures can weigh 4 lbs (and live 12-17 years). They like to roost in high spots where they can open up and warm their wings and bodies in the rising sun, especially if it has been a foggy night. The Dipper ranch's vultures probably feel safe up there and its easier to take off in flight if its cool or calm. [Used to bike many a Sunday morning past a group of vultures with widespread wings on fenceposts on a high ridge above Aromas that caught the morning sun as the misty fog burned off...eerily beautiful and a reward after a long steep climb.]They are the only bird of prey with a good sense of smell, other carrion feeders rely primarily on their eyesight. Rumor says vultures perform a ritualized mating dance on the ground. Maybe you will catch it. I was suprised to find their range extends all the way to Tierra del Fuego. Heard the California Condor population is over 170...any sitings in the Santa Cruz Mountains...not far from the Big Sur?
    Buck
    [Source: Smithsonian Institution "Animal, The Definitive Visual Guide to the World's Wildlife"]

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  6. My cross-canyon neighbor has seen a condor flying high above our hills in recent year. She's dependable about these things. Friend & I went to Pinnacles National Monument this summer to see the pair on nest. Father and nestling had to be removed later to treat for lead poisoning.

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