Thursday, November 30, 2023

Critters of North Idaho: Turkey vulture

by CHRISTIAN RYAN/Correspondent to the Press
| May 18, 2021 1:00 AM

When an animal dies, its rotting corpse would just lie around stinking up the place if it weren’t for nature’s clean-up crew: the scavengers. Among the foxes, bears, and wolverines come the winged undertakers soaring in for a landing. These are the vultures, turkey vultures to be precise.

Turkey vultures (Cathartes aura) get their name from their resemblance to another North American bird, the turkey. They are both covered in dark-colored feathers, and they both have a reddish-colored, bald head. While true turkeys can fly, only doing so when they absolutely have to, turkey vultures are masters of the air. They have a wingspan of 63 to 72 inches and are only 1.8 to 5.3 pounds in weight. They can soar for miles and have been sighted more than 20,000 feet above ground level!

Despite its namesake and bald head, don’t confuse the turkey vulture (Cathartes aura) with its African lookalikes, the ones that clean up the kills of lions and hyenas on the plains of Africa. These birds are not closely related, belonging to very different families. Old World vultures belong to the family Accipitridae, which makes them closely related to hawks, eagles, and kites. New World vultures, like the turkey vulture, belong to the family Cathartidae.

But if New World vultures and Old World vultures are not related, why do they look so similar? It most likely has to do with something biologists call convergence. This is when two unrelated animals adapt in similar ways to deal with similar challenges.

A classic example of convergence is that of the thylacine. This creature was a carnivorous mammal native to the island of Tasmania until it was wiped out in the 1930s. It is often called the Tasmanian wolf because it bore great resemblance to true wolves and other members of the dog family (Canidae).

But despite its appearance, it was really a marsupial, meaning it had a pouch and was more similar to kangaroos and koalas. The thylacine’s dog-like appearance was due to sharing similar behaviors. Like wolves and other true dogs, thylacines were predators that hunted other large mammals.

Turkey vultures share many things in common with Old World vultures for much the same reason. Both are large birds that spend a lot of time on the wing whilst searching for food. They’ve got one of the best noses in the animal kingdom; turkey vultures can smell the stench of decay from over a mile away. Their search for food requires them to descend or ascend quickly, sometimes tens of thousands of feet in a short period of time. Over that distance, they can experience a rapid shift in temperature, from below freezing high in the sky to over a 100℉ at ground level.

Because of this, both types of vultures need the ability to avoid overheating. Their featherless heads allow the birds to lose heat quickly when they need to. And when they get cold, they can simply tuck in their head to conserve heat. Plus, having a bald head is especially helpful when the vultures need to pry into icky carcasses without getting feathers dirty.

Turkey vultures are not endangered, but they are still at risk from people. Some people hunt down these birds because they think that they carry diseases they pick up from carcasses and kill livestock. Both are largely untrue. Vultures are no more unclean than other birds. In fact, their digestive system is especially designed to deal with deadly germs. Their stomach acid is extremely corrosive, killing the bacteria in the carcasses they consume. Also, turkey vultures rarely attack live animals. The few reported cases where this has happened involved animals that were already very sick.

Vultures of any kind, Old World and New World, are important to a healthy ecosystem. Just imagine all of the corpses we’d have lying around without these birds doing their job!

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