Bird Observer: The Birding Journal for New England

Bird Observer

The Birding Journal for New England

February 2016

Vol. 44, No. 1

Front Cover: February 2016

Turkey Vulture by Rosemary Mosco


©Rosemary Mosco

Rosemary Mosco is a naturalist and science communicator. She has created educational stories and graphics about nature for organizations such as the National Park Service and Mass Audubon. Her nature cartoons have an international following and have appeared in various print and web publications. They were also the subject of a 2015 exhibit at the Paleontological Research Institution’s Museum of the Earth in Ithaca, New York. Rosemary has never been vomited on by a Turkey Vulture, but she has been pooped on by various rare birds. Her website is birdandmoon.com.

Turkey Vulture

In recent decades, the sight of Turkey Vultures (Cathartes aura) teetering across the New England sky has become a commonplace event. Turkey Vultures are large, long-winged birds, soaring with their wings set at a slight V or dihedral. They weigh only about two and a half pounds, not much for a bird that looms so large. The feathering is dark brown or black except for the undersides of the primaries and secondaries, which are silvery-gray or gray. The long tail is also gray below. In adults the head is red and the beak is ivory; in juveniles the head is black and the bill is dark and tipped in black. Turkey Vultures can be separated in flight from Black Vultures (Coragyps atratus) by the latter’s short tail and propensity for alternating burst of rapid wingbeats with gliding flight. Up to six subspecies are recognized for the wide- ranging Turkey Vulture; C. a. septentrionalis is the subspecies breeding in the eastern United States. Its closest relatives are the Lesser and Greater Yellow-headed Vultures of Central and South America.

The common name “Turkey” comes from the red head of the adult that supposedly resembles the head of a Turkey. The name “Vulture” comes from the Latin word “vultur,” which means “to pluck or tear,” an obvious reference to the feeding habits of vultures. The generic name Cathartes comes from the Greek “kathartes,” which means “purifier,” referring to the scavenger habits of the species.

The lack of feathering on the head is an adaptation for sanitation, as vultures frequently poke their heads into putrid carcasses. As an adaptation for hot climates, Turkey Vultures often invoke a process known as urohydrosis, where the birds defecate on their legs and feet, which together with high vascularization of their legs, allows temperature reduction by evaporative cooling—how charming. Spreadwing and delta wing postures probably also serve in temperature control, warming the birds in the early morning sunlight and cooling them later in the day. In cold conditions they may retract their bare necks into their feathers to reduce heat loss. Turkey Vultures have been reported to repel predators by projectile vomiting material that smells foul— lovely.

The Turkey Vulture has a vast breeding range. In Canada, breeding distribution is patchy from Southern British Columbia in the west across southern Canada and the Great Lakes to southern Maine in the east. They breed in all of the territorial United States except for a few northern and central states. Farther south, they range throughout the Caribbean and Central and South America to Tierra del Fuego and the Falkland Islands. In Massachusetts, the Turkey Vulture is considered an uncommon but increasingly regular breeder, but it is a common migrant that has been steadily increasing in numbers in recent decades. Its cryptic nesting habits may lead to underestimation of the actual number of breeders. The first breeding record for Massachusetts was in 1954. The Turkey Vulture is a partial migrant. Birds from Massachusetts west to Oklahoma and most western birds migrate south in winter; the eastern birds wintering in the southern United States and the western birds in Central and South America. In our area, migrant Turkey Vultures arrive in March and leave mainly during September in the fall. With their changing breeding status, however, small numbers of Turkey Vultures increasingly winter in Massachusetts

Turkey Vultures prefer forested areas for nesting where rock outcrops, caves, abandoned buildings, and hollow logs occur, and they are isolated from human disturbance. They exhibit strong breeding-site fidelity. Nests tend to be widely spaced but the birds may be territorial around the nest. Agonistic encounters at roosts and carcasses involve extending and lowering the head, opening the bill or biting, and kicking.

Turkey Vultures are monogamous and probably mate for life. During courtship flight, one bird follows the other closely with more than the usual flapping and includes swoops, dives, and evasions. There is no nest building and the female lays the usual clutch of two creamy white eggs on bare substrate. Both parents have brood patches and share incubation duties about equally for the four weeks until hatching. The chicks hatch covered with down, their eyes either open or closed, and they are immobile. Both parents brood the chicks and feed them by regurgitating well-digested food. First flights may occur in eight weeks but ten to twelve weeks is more common. Parents continue to feed chicks until they are around 12 weeks old when they may also join communal roosts.

Turkey Vultures prefer mixed farmland and forest which provide native and domestic animal carcasses and habitat for communal roosting. Turkey Vultures locate carrion both visually and by smell. Unlike most birds, they have well developed olfactory organs. They are opportunistic foragers that will eat carrion from just about any animal group, although they prefer small mammals. They also will eat fish, reptiles, birds, and insects. They sometimes take plant material from a carcass’ intestines, and occasionally even eat fruit. They prefer fresh carcasses but for thick-skinned mammals and reptiles they wait for putrification in order to gain access. They may enter large carrion through the anus, and sometimes through the mouth or nostrils. They pluck or tear tissue from the bones. They rarely take live prey unless it is trapped or injured.

Turkey Vultures in many areas are in competition with the more aggressive Black Vulture for carcasses, but sometimes also benefit from Black Vultures opening large prey. Black Vultures, which lack the olfactory sense, often use Turkey Vultures to locate carrion, follow them in, and displace their less aggressive relatives. Often, when a Turkey Vulture locates a carcass it will be followed in by other Turkey Vultures—a variation on the “invite a friend for dinner” behavior. Usually, only one bird feeds at a time on a carcass. Roadkills are an important source of carrion, and in Massachusetts it has been noted that migrating Turkey Vultures sometimes follow major railroad lines, presumably to harvest train-killed animals.

Turkey Vultures are subject to mammalian nest predation and, as adults, to poisoning from lead shot or bullets. Other problems stemming from human interactions include collision with vehicles, electrocution on power lines, shooting, and trapping.

But the Turkey Vulture has expanded its range in the Northeast since the 1960s, and Breeding Bird Survey data indicate continent-wide population increases. The stable or increasing populations together with its enormous range ensures the future of this highly successful, if not endearing, species.

blog comments powered by Disqus