Black Vulture And Turkey Vulture

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I’m a big fan of vultures and will photograph them every time I have the opportunity to do so.  There are two species of vultures residing in southern Arizona: Black Vultures and Turkey Vultures.  There is also a handful of California Condors living by the Grand Canyon in the northern part of the state.  Turkey Vultures are much more common here than Black Vultures during the hot months.  They tend to vacate the area in winter.  Black Vultures, although much less common, live here throughout the year.

The two species are related to each other and aren’t closely related to anything else.  They aren’t related to Old World vultures.  Any resemblance is a consequence of convergent evolution and not genetic relationship.  Ornithologists have debated as to which species in this hemisphere are relatives of our vultures.  The current thinking is that vultures in this hemisphere are distantly related to falcons.  However, ornithologists thought previously that our vultures might be cousins to storks.

I was fortunate recently to photograph a Black Vulture and a Turkey Vulture roosting side by side.

The image shows off the birds’ similarities and differences.  The two species are about the same size, with the Black Vulture having a chunkier physique and the Turkey Vulture definitely being longer and leaner.  Both species have bald heads.  The Turkey Vulture’s head is pink or red whereas the Black Vulture’s head is a very dark gray (to confuse matters a bit, juvenile Turkey Vultures have gray heads).  The Turkey Vulture has a more raptor-like beak than does the Black Vulture, with a pronounced hook at the tip that the Black Vulture lacks.  The Turkey Vulture’s beak is white and the Black Vulture’s beak is gray.  Both birds have long legs but the Black Vulture’s legs are a bit stockier than are the Turkey Vulture’s legs.  Both species have white legs due to a unique vulture trait.  The birds urinate on their legs and the white surfaces are residual urea.  Ornithologists believe that the evaporation of urine from the birds’ legs lowers the legs’ surface temperature and that in turn cools blood circulating beneath the skin.  Anything to cool off in our heat!

An image of a Turkey Vulture descending shows off two additional features common to both species.  The bird has gigantic wings in proportion to its body, an attribute that enables it to soar effortlessly.  Turkey Vulture wings are proportionately longer and thinner than the Black Vulture’s short and very broad wings.  However, like the Turkey Vulture, the Black Vulture has absolutely enormous wings in proportion to its overall size.  Black Vultures, if anything, are even better at soaring than are Turkey Vultures.  Another attribute, shared by both species, is the Turkey Vulture’s relatively weak feet.  Vultures’ feet are definitely un-raptorlike.

Images made with a Canon 5Div, 100-400mm f4.5-5.6 ISII zoom lens, aperture preferred setting, ISO 500, f6.3 @ 1/2000.

 

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