Vultures in Frederick County
Most often seen in our area are Turkey vultures (Cathartes aura), a large bird with a wing span of 5 to 6 feet and weighing approximately 3 to 5 pounds. Females are slightly larger than males, with both sexes having the same dark brown coloring, with red-colored, wrinkled heads bare of feathers. Flight feathers are light gray to silver in color and are readily see on the underside of the wings in flight. Turkey vultures have short, hooked ivory beaks, and bare legs and feet with short talons. Immature Turkey vultures are almost white in color, with grayish heads and black-tipped beaks. The lighter coloring disappears as the birds mature.
Also seen in our area are Black vultures (Coragyps atratus), which have shorter tails and slightly less wingspan than Turkey vultures. Black vultures are darker, and have a gray colored, wrinkled bare head with a longer, hooked beak that is dark on the upper beak. Immature Black vultures have a black, featherless head and cinnamon or pinkish down. Black vultures forage in flocks and flap more often in flight, due to their slightly smaller wing span and tail with slightly heavier body. Turkey vultures soar for longer distances with more grace, and often glide in circular patterns. Both of these birds rely on a diet of carrion, but will eat vegetable matter and insects. Both vultures can live to about 16 years in the wild and longer in captivity.
Turkey vultures rarely kill live prey. However, Black vultures will occasionally feed on live prey. Turkey vultures have a sharp sense of smell which helps them locate carrion in the early stages of decomposition. Black vultures have sharp eyesight for locating a meal. Black vultures possess less olfactory sensitivity and at times follow Turkey vultures to carrion, and then drive off the more solitary Turkey vultures. Both species range over a dozen or more square miles, is areas that provide a variety of habitat, including wooded areas for roosting.
Black vultures are believed to occasionally mate for life, but often select new mates during a mating ritual involving flying pursuit followed by the males strutting, flapping and puffing. The more monogamous Turkey vultures mate for life after a similar mating ritual of flying pursuit followed by the males hopping around with wings partially open. Females of both species lay eggs on the ground in a sheltered area such as under a log, rock outcrop or cave, without building nests. Both parents take turns incubating the eggs during an approximately 38 day incubation period. Black vultures typically mate every year and have clutches of 3 eggs. At birth Black vulture young weigh only about 2.5 ounces and stay in the nesting area for several months. Turkey vultures typically lay only 2 eggs, with the small chicks having a longer dependency period that reduces mating to every other year. Both birds forage for their young and regurgitate food to feed their chicks. Food regurgitation is also practiced by adult vultures as a defensive measure when confronted by danger. Both Turkey vultures and Black vultures are Federally protected by the Migratory Bird Treaty Act.
Article by FCFCDB
Nature Notes for 12/22/2013