The turkey vulture (Cathartes aura) is a familiar sight in the skies over much of North and South America. Knowing what the turkey vulture eats is one of the most intriguing things about this bird. These birds are nature's clean-up crew, playing a vital role in the ecosystem by feeding on carrion. While their feeding habits may seem unappealing to some, they are essential for curbing the spread of dangerous diseases and bacteria. This article delves into the diet of the turkey vulture, exploring what they eat, how they find their food, and their role in the food web.
What Turkey Vultures Eat
The turkey vulture feeds nearly exclusively on carrion, consuming carcasses of all types of animals and sizes. This includes everything from washed-up minnows and mice to cows and even the carcasses of washed-up whales. According to studies that examined the pellets regurgitated by turkey vultures, its diet includes carrion from common animals without discrimination based on size. They prefer freshly dead animals, but often have to wait for their meal to soften in order to pierce the skin. Turkey vultures are opportunists, feeding on what’s available to them in the landscape and throughout the annual cycle. The type and amount of carcasses the turkey vulture consumes vary according to season.
Seasonal Variations in Diet
The diet of turkey vultures changes according to seasonal die-offs or breeding events of animals. For instance, on the Pacific coast of South America, turkey vultures feed mostly on the placenta of female sea lions giving birth and carcasses of pups that die during the birthing season. In the Amazon basin, turkey vultures congregate around the seasonal die-off of fish during the dry season. Studies in Pennsylvania and Virginia noted an increase of road-killed deer in the spring months when deer are more active and likely to be hit by vehicles.
Turkey Vultures as Opportunistic Hunters
Turkey vultures feed mostly on carcasses of dead animals but are capable of killing small ones. On one occasion, a turkey vulture was observed chasing and killing newly hatched chicks of a grouse. A turkey vulture once harassed nestlings of great blue herons so that they would regurgitate their crop content for the vulture to eat. On another occasion, they caught and ate live minnows stranded on a creek with little water. Overall, the turkey vulture is capable of killing very small and vulnerable prey in an opportunistic fashion.
How Turkey Vultures Find Food
Turkey vultures have a remarkable sense of smell that allows them to find even a shrew on the forest floor of a dense-canopied forest. They can locate carcasses on the forest floor beneath dense forest canopies. In North America, the Turkey Vulture is the only vulture with a highly developed sense of smell. They also use their eyesight to search for food. Turkey vultures need to cover vast areas using the least amount of energy to search for food. Depending on the region and time of the year, thermal updrafts begin to form between 3 to 4 hours after sunrise, which they use to soar effortlessly.
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Foraging Behavior
Turkey vultures feed in any habitat type, always on the ground, because most carcasses are found there. Unlike hawks and falcons, turkey vultures cannot take even the smallest carcass from the ground to a branch. Turkey vultures can carry small items in their beaks, such as mice or snakes. An unusual sighting was a turkey vulture carrying what appears to be a rib bone with some dry meat still attached to it. Turkey vultures seldom carry things. Turkey vultures return to roost sites every night after foraging for food and feeding. When they feed on a large carcass, turkey vultures return to the same carcass for as long as there is food. Turkey vultures forage for food and eat exclusively during the day. They could not perform the effortless and low-energy flight they normally do because thermal updrafts do not form at night. Furthermore, cool air tends to settle lower to the ground.
Turkey Vulture's Role in the Food Web
An essential tenet of a food web is that animals must eat other animals, other living things, or things that at one point were alive. Primary producers or plants, that convert solar energy into food energy. Primary consumers cannot create food energy from the sun and rely on primary producers to obtain their food energy. Primary consumers are typically herbivores, from small insects to cows. Secondary consumers eat the primary consumers. They are typically known as predators capable of catching and killing primary consumers. Secondary consumers sit high on the food web. Generally, no other animals target them as food. Tertiary consumers eat the secondary consumers, and on rare occasions, even primary producers. Tertiary consumers are diet generalists.
The turkey vulture food web describes the energetic relationships between live animals. The turkey vulture sits on top as a fourth trophic level or in the center of the food web. Perhaps a better way to represent the turkey vulture’s food web is by a circular food web rather than a pyramid. In the representation below, primary, secondary, and tertiary consumers are potential food for the turkey vulture. In the turkey vulture food web, grass represents the primary producer. Deer and rabbits are primary consumers, which are prey for secondary consumers such as the bobcat. The turkey vulture is a tertiary consumer standing at the center of its food web.
Physical Adaptations for Scavenging
Compared to other birds of prey, the turkey vulture has weak talons and beaks because they do not need strong, sharp talons and beaks for hunting. This is because they are primarily scavengers, feeding on dead animals. Turkey vultures only eat small bones of small mammals such as mice and shrews. Although unable to ingest large bones, the turkey vulture is a specialist in scraping muscles and tendons attached to the bones of large animals. Vultures lack feathers on their heads so they can more easily keep themselves clean when eating, since they often insert their heads completely inside the carcasses they feed on. The legs of vultures are usually coated white, due to the dried uric acid of their excrement. Vultures will mute-excrete waste-onto their legs, serving two different purposes: In warm weather, muting on their legs is part of their thermoregulation - it helps to cool down their body temperature. When vultures step into a carcass, touching possibly contaminated flesh, they risk coming into contact with bacteria. Their stomachs have strong enzymes that kill off dangerous toxins and microorganisms. Vultures lack the powerful feet that are characteristic of true raptors like eagles and hawks. They have long toes with blunted talons, which make it easier for vultures to walk on the ground. Turkey Vultures often place one or both feet on their food when eating; Black Vultures typically do not use their feet when feeding. Vultures have long, hooked bills designed for tearing pieces of food.
Competition and Social Behavior
Turkey vultures compete for carrion with other scavengers. In North America, they compete with black vultures. Black Vultures are more aggressive than these Vultures and will often follow them to carcasses and displace them from the carcass. They form communal roosts which facilitate group foraging and social interactions. Groups of vultures spiraling upward to gain altitude are called "kettles".
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Conservation Status
The current world population of this New World species almost certainly exceeds five million birds. Most populations of this adaptable species appear to be thriving. In general, the this Vulture’s beneficial role as a scavenger is recognized, and the species is not persecuted. Unfortunately, this was not always the case. In the past, these Vultures were shot because ranchers and farmers mistakenly believed that they spread diseases and contaminated watering holes for livestock, although there is no evidence to substantiate this claim. These Vultures also have been blamed and persecuted for livestock losses they were not responsible for. Individuals, historically and currently, are sometimes mistakenly poisoned at baited carcasses and are killed or injured in steel leg-hold traps set for mammals. Environmental contaminants including lead, mercury, and insecticides can poison these Vultures. Overall numbers of Turkey Vultures remained stable during the DDT era of the 1940s to the early 1970s, even though eggshell-thinning and reduced reproductive success due to pesticide contamination occurred in some areas. Turkey Vultures frequently feed on roadkill, and collisions with automobiles are a common source of mortality in some areas. The species also collides with aircraft; between 1989 and 1992, Turkey Vulture collisions with United States Air Force aircraft resulted in two human deaths, three airplane crashes, and a loss of more than 21 million dollars.
The main concern is lead shot that ends up in carcasses or gut piles left by hunters. The animals eat the shot and eventually suffer lead poisoning. Other threats include trapping and killing due to erroneous fears that they spread disease.
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