Turkey vultures migrate through our region at this time of year, bringing with them stories as old as the dinosaurs. With their bare heads and large size, it’s easier to imagine this species’ hotly debated dinosaur origins than those of a hummingbird. But one less obvious way the Turkey Vulture reminds us of how birds’ ancestors survived a mass extinction 65 million years ago is its keen sense of smell.
It’s commonly thought that birds are nearly entirely visual and auditory. After all, the portion of their brains devoted to processing the bouquet of a flower, the funk of a friend, or the reek of a rotting carcass is typically very small. But for some species, like Turkey Vultures, smell is critical. It can aid navigation, locate food, or certify kinship.
Paleontologist Darla Zelenitsky of the University of Calgary in Canada compared fossil skulls with those of modern birds (and tapped existing data) to determine how much of their circuits were aimed at smell. It seems the ancestral birds’ sense of smell greatly sharpened after the cataclysm, believed to have been an asteroid collision with Earth. More here from ScienceNOW. One can imagine buzzards circling the skies of a world of death.
Turkey Vultures and other carrion eaters play a critical role in recycling nutrients and curbing the spread of disease by acting as nature’s cleanup crew. Though their diet, defensive arsenal of projectile vomit and poo, and undertaker visages creep many people out, these birds soar gracefully on thermal vents (here gyring Fibonacci is at it again) and they can even save human lives: Turkey Vultures are sometimes used to locate natural gas leaks because they’re drawn to the smell of an additive, ethyl mercaptan.
Though Turkey Vultures fly great distances and their physiology reminds us of a remarkable global period, they’re actually pretty localized. Vultures in other parts of the world are unrelated, providing a striking example of convergent evolution — similar mutations exploit similar opportunities, and in the end you get a similar animal or plant despite genetic isolation. To find a close relative of the Turkey Vulture just head down to a local wetland. If you’re lucky you’ll spot it — the far more celebrated Blue Heron.