Turkey vultures, the most common of our area's large birds, are both ugly and beautiful. Both sides of their character contribute to their success, and they've been successful for a long time. The fossil record shows that they've been on earth for 65 million years, and individual birds can live up to 50 years.
With an adult wingspread of about 6 feet, they're sometimes
mistaken
for eagles. The usual view of a turkey vulture is from below,
where
you'll see distinctive two-tone coloration. 
Their
body and wing linings are black, the flight feathers on their wings are
a lighter shade of gray. In flight they rarely flap; they soar
with
their wings lifted upward to form a shallow V shape, and they rock
unsteadily
from side to side. The uplifted V shape is called dihedral angle,
or simply dihedral.
Sometimes their wings take on an ugly ragged look with many feathers missing. This is because they molt, shedding old flight feathers in the fall and growing new replacements by spring.
Viewed close-up on the ground, turkey vultures definitely won't
win
a beauty contest.
Their bare red heads and their hooked beaks are adapted for reaching
into the carcasses of dead animals and tearing flesh. Turkey
vultures
do occasionally take small live prey, but their talons are too weak to
make them efficient killers. Their large size and low speed also
make them relatively easy for would-be prey to spot.
Size also makes them poor fliers in flapping flight. If you surprise one by the roadside it's best to do it when your sun roof is closed or your convertible top is up... when paniced into an abrupt departure they take two-legged running hops and flap furiously to get airborne, often regurgitating their current meal of carrion in mid-air to lighten their load. Few things in nature can match regurgitated carrion for being utterly vile, stinky, and generally disgusting to humans.
Of course regurgitated carrion is exactly what they feed their young. Turkey vultures "nest" in groups, and these areas are easy to identify by their stench. They don't build true nests, but use whatever natural features offer a reasonable place to lay and incubate two or three egg. Incubation lasts 38 to 41 days, and the black-headed young reach full growth in a mere 70 to 80 days.
The beauty of turkey vultures becomes evident in the air, where
they
exercise magnificent soaring skills honed by nature. 
They
climb on the slightest updrafts, usually using thermal convection for
their
cross-country flights. They also fly on vertically-deflected breezes,
which
glider pilots call ridge lift. Folsom Dam is one of the best
ridge
lift generators in our area; mornings often bring up to several dozen
turkey
vultures soaring over it, waiting for heat from the sun to trigger
thermals.
Flying effortlessly at altitutes from a few hundred feet to a few thousand, they look for food with eyes whose vision is several times sharper than human sight. Their field of vision is enormous, almost a full circle, but they still have stereoscopic vision for looking forward.
Recently an aerodynamics expert at Edwards Air Force Base studied similar soaring birds and found that they use principles that man thinks of as modern in aircraft. One example is variable stability: Normally soaring birds such as hawks, eagles, and turkey vultures use neutral stability, which gives them a very efficient glide. When the air is turbulent they shift to positive stability, which enables them to keep flying without having to constantly correct for every puff of wind.
Cruising at speeds clocked from 15 to 21 mph, many turkey vultures from our area migrate to southern California for the winter and return in the spring. Others simply stay here all year.
Turkey vultures may have an ugly face, but they offer dances of
aerial
beauty for our pleasure.