Near where I live, a high-tension power line cuts through the bottomlands along Northeast Creek, providing a perfect roost for about 150 vultures, backlit at dusk along a rural road.
Lately the numbers have been dropping, from 70, to 40 to 30 as migrants leave and nesting starts. They pack into the tops of from one to four steel pylons. I recently found a heron rookery nearby, which could provide prey and nest sites.
Around 4 p.m. birds start sailing in low over the trees, singly or in small groups, coming mainly from the northeast, along the creek, or from the southeast or northwest along a gasline. They could come from as far as Cary and Carrboro.
Most are turkey vultures, very big, dark brown birds with whitish trailing edges on their wings and purplish heads, black in juveniles. Some hawks mimic this wing pattern, possibly to confuse prey. Turkey vultures tilt back and forth and hold their wings in a slight V-shape, with upswept wingtips, unlike most hawks and eagles.
The roost has at least three black vultures, more common at Eno River State Park. They are black, with triangles of white at their wingtips, wide tails, and gray heads, black in juveniles. Their broad wings appear curvy and are held flat in flight.
Taxonomists debate whether vultures should be classified with hawks or with storks. American vultures probably originated in Europe, but are different from Old World buzzards. Turkey vultures are classified as Cathartes aura
. Cathartes means cleanser and aura probably is an indigenous name. Black vultures are Coragyps atratus, meaning raven-vulture clothed in black. Vulture itself comes from "to tear" in Latin. Each species scavenges differently, so they can share the same habitat.
Turkey vultures rarely flap, gliding on winds around hills and thermals, rising so high that they become specks. Just imagine how much of the Triangle they can see up there! Their unsteady flight helps them scent carrion. Black vultures rely on sight and fly higher, but have to flap more and require stronger thermals, so they can't soar as early. When they see a turkey vulture with a meal, they dive, making a sound compared to an aeolian harp. Black vultures cooperate, mainly with kin, and are more aggressive, so they monopolize a carcass, despite being smaller, but groups require bigger carcasses.
Vultures can't open thick skin, so they have to wait for other scavengers or decay. Turkey vultures scavenge animals such as deer, skunks, and tadpoles, but also hunt insects, fish, and vulnerable birds, pick over cowpies, and eat grapes and rotten pumpkins and coconuts.
Black vultures are more predatory, attacking animals like possums and calves, though they also like some tropical fruits. They formerly hung around meat markets in Southern coastal cities like Charleston, and were called South Carolina eagles.
In some cultures, vultures are allowed to eat corpses. It seems to me that there is some aesthetic appeal in being consumed and, in a sense, reborn by these majestic birds, rather than mouldering in a grave.
This is nesting season, though parents sleep in roosts when possible. Vultures mate for life and are completely monogamous. Vultures court with dancing and follow flights, in which one bird follows the other at a higher level, swinging down at the leading bird. A pair hangs around a future nest site weeks before egg-laying. Turkey vultures probably laid their eggs earlier in March, and black vultures about two weeks earlier. Vultures lay their spotted eggs, usually two, in unfurnished hollow logs or stumps, burrows, thickets, old heron nests, crevices, and cabins along the Eno, which they re-use for many years.
A study found that Chatham County's black vultures only nested in buildings, thus their numbers declined as buildings were destroyed, but now they might be rebounding. Both parents take turns sitting, and trespassers might get vomited upon. After 60 to 80 days, turkey vulture chicks can fly and soon leave to roost with other juveniles. This is very different from juvenile black vulture, who are still sometimes fed by their parents after eight months.
Families stay together for a year, after which juveniles follow experienced birds to food, which is not welcomed. Allies cement their friendship by preening each other's heads and necks. Turkey vultures breed after two years, and can live at least 33 years in captivity, but black vultures wait a whopping eight years, and can live to at least 25 in nature.
Vultures are less persecuted today, but are poisoned by lead shot and pesticides, and killed by cars. Migratory turkey vultures are still exposed to egg-weakening DDT, and they don't yield to aircraft. But, despite many changes, effortlessly soaring, swift, and useful vultures remain common.