Turkey Vulture
| Scientific Name | Cathartes aura |
| Survival Strategy | Long-distance Migrant / Neotropical Migrant |
| Arrival in Upper Midwest | Mid to late March |
| Departure | Mid-October |
| Destination | Central and South America |
| Conservation Status | Least Concern |
Spring
In mid to late March, breeding pairs of turkey vultures return to the upper Midwest, often reusing the previous year’s nest site for egg-laying. Typically, they seek areas secluded from human disturbance, such as rock outcroppings or hollow tree stumps, but they may also use abandoned automobiles, old farm buildings, and even deer stands. They do not construct a nest; instead, they simply lay their eggs on the surface of the nest site. Female turkey vultures lay two eggs in late April, which hatch in 28 to 40 days as adorable off-white, down-covered chicks. After ten days, the chicks lose the down that covers their head.
Summer
Young vultures fledge by late July to early August and join the communal roost in late August.
Fall
Turkey vultures begin gathering in large pre-migration roosting groups in September. The trigger for their southern migration is likely the onset of colder temperatures, usually by mid-October. Frozen carrion is challenging to eat, and snow cover will hide most carcasses.
Winter
Turkey vultures from the upper Midwest overwinter in Central and South America.
Behavior
Temperature Regulation
Turkey vultures do not sweat. To lose excess heat in the summer, vultures use “gular flutter.” By rapidly flapping the gular skin in their throat (think pelican pouch), they create a radiator that transfers heat from their blood vessels to the outside air.
They will defecate on their legs in a process called Urohidrosis. As the water in the digestive wastes evaporates, it cools the vulture’s legs. This evaporative cooling is the same process that makes you cold when you step out of a shower.
On colder mornings, turkey vultures will warm up using their dark feathers as solar collectors. They spread their wings and face the sun in what is known as the “horaltic pose.” This behavior is also common in other birds such as hawks, herons, and cormorants.
Defensive Vomiting
Turkey vultures will vomit as a defense against predators. Their projectile vomiting has a range of around three meters (10ft) and is as pungent as you would expect rotting deer flesh soaked in stomach acid would be. This odiferous slime is an effective predator repellent and makes the bird lighter for quick liftoffs. This stinky goo is an unfortunate reality for heroic staff at wildlife rehabilitation centers working with injured turkey vultures.
Turkey Vultures Rock! (contorted soaring)
On warm sunny days, turkey vultures will use the updrafts created by thermals to power their near-effortless soaring. Strong thermals are not available on cool and cloudy days or when flying at low altitudes, so turkey vultures often use contorted soaring to stay in the air. Even on cool days, small-scale turbulence can occur when wind moving over an open field is forced upward as it hits a building or wooded area. Vultures can surf this turbulence by rocking back and forth to gain altitude. A flight that appears to be a turkey vulture struggling in unstable air is really the agility of a skilled flier on display.
The vulture is more stable in turbulent air by holding its wings in a V-shape (dihedral). Many aircraft designs incorporate dihedral-shaped wings for increased stability.
Contorted soaring at low altitudes makes it easier for vultures to use their sense of smell to locate carrion in wooded or brushy areas without attracting attention from other scavengers.
Physiology
Sense of Smell
Turkey vultures have a keen sense of smell, powered by a large olfactory bulb, an area of the brain responsible for processing odors, and a nasal cavity not divided by a septum which increases the amount of air into the sinuses.
Turkey vultures can detect the chemical compound given off by rotting flesh (ethyl mercaptan) from miles away, even when the source is beneath the dense canopy of a rainforest. Natural gas companies add ethyl mercaptan to their odorless fuel so the scent will alert consumers and pipeline technicians of dangerous leaks. When leaks occur along natural gas pipelines in remote areas, turkey vultures will sometimes circle above, attracted by the odor and the false hope of a tasty putrid carcass. This behavior has made gas leaks in rural regions easier to locate.
Nightly Torpor
Like the black-capped chickadee, turkey vultures can intentionally become slightly hypothermic at night. By reducing their body temperature by about six degrees Celsius (11°F), they can conserve energy to compensate for times when carrion is scarce.
Diet
Turkey vultures do not hunt prey and rely on carrion for almost all food. One vulture can eat about one hundred pounds of carrion per year and then redistribute those nutrients across the ecosystem.
Vultures will regularly visit garbage dumps in search of food and, in the process, ingest discarded plastic bags. Not only is the plastic detrimental to the vulture’s health, as they cough up pellets (similar to owl pellets), they disperse the plastic into remote areas.
If the opportunity presents itself, turkey vultures may dine on an occasional live frog or sick bird.
Lifespan and Mortality
The average lifespan of a turkey vulture is ten years, with an annual survival of around 75%.
Predators
Raccoons are nest predators, and great horned owls will prey on young birds as well as adults.
Humans are likely the primary cause of turkey vulture mortality. These beneficial scavengers are sometimes trapped, shot, or poisoned after being wrongly accused of killing livestock. With feet more like a chicken than an eagle, turkey vultures do not have the weaponry needed to kill for their food. An unfortunate consequence of eating roadkill is the accidental collision with cars.
Climate Vulnerability
A warming climate will likely increase the range of the turkey vulture, although intense spring heatwaves could reduce nesting success.
Never Stop Learning
Snapple® Cap Worthy: Turkey vultures do not have a syrinx (a bird voice box) and can’t create a song or call. At best, they can manage to produce a low, guttural hiss.
Ecotourism: The Baraboo Hills of South-central Wisconsin is a pre-migration staging area for turkey vultures. Visitors will see several hundred birds soaring around these quartzite outcrops in September and October.
References
| Kirk, D. A. and M. J. Mossman (2020). Turkey Vulture (Cathartes aura), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.turvul.01 |
| In Wisconsin:Turkey Vultures https://video.pbswisconsin.org/video/in-wisconsin-turkey-vultures/ |
| Turkey Vulture – Wisconsin eBird https://ebird.org/wi/species/turvul/L454180 |
| Cabello-Vergel, J., Soriano-Redondo, A., Villegas, A. et al. Urohidrosis as an overlooked cooling mechanism in long-legged birds. Sci Rep 11, 20018 (2021). https://doi.org/10.1038/s41598-021-99296-8 |
| Turkey Vultures Have a Keen Sense of Smell and Now We Know Why https://www.smithsonianmag.com/smithsonian-institution/turkey-vultures-have-keen-sense-smell-and-now-we-know-why-180967599/ |
| Ballejo F, Plaza P, Speziale K, Lambertucci A, Lambertucci S. Plastic ingestion and dispersion by vultures may produce plastic islands in natural areas. Science of The Total Environment. 2020;755:142421. doi:10.1016/j.scitotenv.2020.142421 |
| The Biology of Vultures – Raptors International http://www.raptors-international.org |
| When It Comes to Smell, the Turkey Vulture Stands (Nearly) Alone https://baynature.org/article/comes-smell-turkey-vulture-stands-nearly-alone/ |
| Turkey Vultures – Devil’s Lake State Park Area Visitor’s Guide https://www.devilslakewisconsin.com/learning-center/turkey-vultures/ |
| How Climate Change Will Reshape the Range of the Turkey Vulture https://www.audubon.org/field-guide/bird/turkey-vulture |
| Julie M. Mallon, Keith L. Bildstein, Todd E. Katzner, In-flight turbulence benefits soaring birds, The Auk, Volume 133, Issue 1, 1 January 2016, Pages 79–85, https://doi.org/10.1642/AUK-15-114.1 |