Each year, the Wildlife Center admits and treats about 50-60 Black and Turkey Vultures. Common causes of admission for these two species include lead toxicosis, gunshot injuries, and collisions with vehicles. While some people may think of vultures as “gross”, they are a vital part of our balanced ecosystem and play an important role as natures “clean-up crew”. Watch our episode of UNTAMED on vultures, and read below to learn more about these charismatic animals.
Turkey vultures are a common sight across much of North America recognizable by their large silhouette and distinctive wing-spreading behavior. But why do these scavengers sit for hours with their wings held outwards? This unique posture actually serves several important purposes.
Thermoregulation
One of the primary reasons turkey vultures spread their wings is for thermoregulation. With mostly featherless heads and necks, these birds are vulnerable to changes in temperature. Holding their wings out allows blood vessels near the surface to release excess heat on hot days or trap heat to stay warm in cooler weather. By adjusting wing position as temperatures fluctuate, turkey vultures maintain optimal body temperature.
Drying Feathers
Turkey vultures frequently come into contact with fluids and bacteria when feeding on carcasses Spread wings enable moisture to evaporate quickly in the sun and wind, keeping feathers dry and functional for flight This is essential since vultures rely on soaring and keen eyesight, not smell, to locate food.
Increasing Mobility
Although adept fliers, turkey vultures are clumsy on the ground. Their wings provide balance and stability for moving about before taking off. Spread wings also maximize the visual area scanned for potential food sources below.
Social Signaling
Seeing others with spread wings often stimulates turkey vultures to follow suit. This behavior is believed to maintain social cohesion when birds are gathered in large groups. The visual display may also enhance vocal communication between flock members.
Mating Displays
Dominant male turkey vultures hold wings open to attract females and establish territory. Females likely do the same to signal receptiveness and assess potential mates. The large, spread wings make birds appear bigger and convey strength.
Sunning and Preening
Sunlight exposure may help control bacteria, fungi, and parasites on skin and feathers. Turkey vultures also use their spread wings to preen and straighten flight feathers more easily. Proper preening maintains the strong, aerodynamic wings critical for flight.
Antimicrobial Sunlight
Ultraviolet rays in sunlight have antimicrobial effects that could help disinfect turkey vultures when exposure occurs through wing-spreading. This may be an evolutionary adaptation to counter bacteria encountered on carrion.
Thermal Gradient Regulation
Recent research found turkey vultures spread their wings more often when wet. This supports the theory that wing-spreading creates a thermal gradient to transfer heat energy away from the body core, aiding cooling in hot environments.
Turkey vultures clearly do not spread their wings solely for resting! This multifunctional posture critically aids temperature regulation, feather drying, visual hunting, mating, preening, sunning, and heat transfer. Next time you see a turkey vulture spread-eagled, appreciate the intricate evolutionary adaptations behind this behavior key to the species’ success.
Black vs. Turkey Vultures
Black Vultures have black plumage, bare black heads, and white patches under their primary feathers. Black Vultures rely on sight to find their food.
In flight, Black Vultures can be identified by their small patches of white feathers at the tips of their wings. Their tails are short and only extend the length of their legs.
Mature Turkey Vultures have dark plumage and featherless red heads; the undersides of the flight feathers are paler. An immature Turkey Vulture’s head is dark gray. Unlike most bird species, Turkey Vultures rely on their sense of smell to find prey.
In flight, Turkey Vultures wings are largely silvery-white on the undersides. Their tails are also generally longer than Black Vultures.
Vultures are scavengers and feed primarily on carrion. They rid the landscape of deteriorating carcasses and help curb the spread of dangerous diseases and 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. 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. They disinfect themselves with the highly acidic uric acids by muting onto their legs.
- In the early mornings, vultures often will sit with their wings spread wide, increasing the surface area of their bodies so that the sun can more easily warm them. This is called the “horaltic pose”. This posture also helps control ectoparasites like feather lice and flat flies.
- Black Vultures are “family-oriented” birds – they feed their young for up to eight months after their young have fledged and often stay together in family groups.
- Vultures lack a voice box; their vocalizations include rasping hisses and grunts.
- According to All About Birds, “The word vulture likely comes from the Latin vellere, which means to pluck or tear. [The Turkey Vultures] scientific name, Cathartes aura, is far more pleasant. It means either golden purifier or purifying breeze.”
- Vultures can live to be 25 years old.
Vultures were once regarded as largely beneficial and were well-tolerated in human-populated areas. A negative attitude toward these scavengers was developed in the early 1900s when people became concerned that vultures might increase the spread of disease, despite strong evidence to the contrary.
You can help vultures by sharing your appreciation of these misunderstood scavengers with other people. Learn more about lead toxicosis and help us reduce the number of vultures (and eagles!) we see suffering from the effects of lead toxicity.
Why Do Vultures Spread Their Wings in the Morning Sun?
FAQ
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