With their bald heads, beady eyes, and habit of shredding messy roadkill, turkey vultures look like birds only a mother could love. But this week we all should look up and tip our hats at the key role they play in the natural world. Saturday September 5 is International Vulture Awareness Day.

These vultures’ Latin name, Cathartes, means “cleanser” or “purifier,” because of the service they provide as nature’s housecleaner.

Turkey vultures have naked red heads, all the better to stay clean as they dine on dead and decaying meat. Their black wings—about six feet in span—show white on the underside. They display an overall V-shape as they soar in the blue skies of the Colorado Plateau.

Using their good sense of sight and smell, turkey vultures normally fly low as they scan for food. But in the fall, “TVs,” as they’re called, gather into large groups called “kettles.” Together, they catch thermals and updrafts, spiraling thousands of feet high on their southbound migrations to Mexico and Central America. Hawks and other soaring birds may also join these impressive flocks.

Kettling could be pre-migration staging behavior, alerting others that it’s time to go. Collectively the birds can also conserve energy while gaining altitude for the long-distance migrations. Either way, a big kettle can be a spectacular sight.

The Turkey Vulture Migration Project tracks tagged birds through states in the U.S. Learn more about that at vulturemovements.org. Or find out about events held to celebrate vultures at vultureday.org.