Turkey Vultures and other soaring birds

Ever wonder what happens to road kills and other dead animals? Sometimes they are collected or buried by road maintenance folks, but more often they are removed by one of our more important, and often ignored, avian neighbors, the Turkey Vulture.

These birds are found throughout Thurston County but in relatively small numbers. They usually leave for the winter months, migrating to the southern states and returning in the early spring to breed.

Turkey Vultures feed on carrion, eating the flesh of dead animals, primarily larger mammals. They have strong stomach acid and can digest rotting flesh without ill effects. They have sharp, hooked bills and can tear flesh easily and their naked heads (which are red in adults – like a turkey) seem to be adapted to probing carrion.

They have a nesting preference for rock ledges and cave mouths in remote locations as communal nesting sites but may nest in a variety of other places. They feed their young with regurgitated food which they carry back in their stomachs. These are not usually backyard birds, and nesting in remote locations is a good thing since one of their main defensive weapons when disturbed is projectile vomiting!  

Turkey Vultures find their food using their sense of smell. As they are soaring overhead one might think they are looking for dead animals, but what they’re doing, primarily, is sniffing the air to detect the smell of rotting flesh. (Of course, they are watching other vultures and might respond to another vulture descending to feed, too).

The importance of smell was proven in the 1930s interestingly. The Union Oil Company was seeking a way to detect leaks in its natural gas pipelines. Natural gas is colorless and odorless, and thus leaks were difficult to detect. After some experiments, the company determined that by adding a strong-smelling sulfur-related organic compound, mercaptan, they could create an unpleasant odor that immediately alerted customers about the risk of a leak.

But what does that have to do with Turkey Vultures? Mercaptans and related compounds are released by rotting flesh and, to us, smell terrible. Once Union Oil started adding mercaptan to its gas pipelines, they found that Turkey Vultures were circling around and descending on sections of the pipeline. The birds were smelling the rotten flesh odor being emitted from a pipeline leak, and thus the birds were serving as unpaid leak detectors.

You are most likely to see Turkey Vultures (usually more than one) soaring in the open countryside, although occasionally they might be seen on the ground at or near a roadkill.  As they soar, they hold their wings in a deep distinctive “V” shape and seem to tip side-to-side and they circle. They are two-tone black, with the outer feathers appearing lighter gray. These are big birds – larger than a Red-tailed Hawk but somewhat smaller than a Bald Eagle.

In profile, they look much different than a raptor. Their heads are much smaller and appear a little bumpy when compared to a hawk or eagle. Also, when soaring they are usually silent and do not fan their tails. Learning to quickly identify vultures in the air (deep “V,” tippy flight) can help you distinguish them from some of our common soaring birds.

Bald Eagles are also known to be carrion eaters. A Bald Eagle adult is perhaps the easiest soaring bird to identify since its bold white tail and head are very distinctive. In profile, their wings are held nearly flat and their soaring group will be relatively small (2-4 individuals). Eagles often will vocalize with their distinctive high-pitched “whinney.”

Another common soaring bird in our area is the Red-tailed Hawk. This species is smaller, but sometimes size is difficult to judge in a soaring bird. The adults have an obvious red-tail (not a big surprise, I imagine) and appear much browner, overall, than either the eagle or vulture. Also, a Red-tailed Hawk has a brownish belly that contrasts boldly with a white breast patch.

One final bird that you might see soaring overhead is the Osprey. This fish-eating raptor will often use a platform as a nesting location. There are several Osprey nests (large piles of sticks) on communication towers in our area and you might spot an Osprey returning to its nest carrying a fish. These birds are similar in size to a Red-tailed Hawk but behave very differently. They fly over shallow water, sometimes at great heights, before spotting prey and diving into the water to catch fish with their claw-like feet.

Ospreys are brownish on their backs in contrast with their white bellies and legs. Their heads are white with a broad brown stripe through their eyes. Ospreys seldom soar, but while flying they lift their wings into a vertical “V” that is a good field marker, even from a distance.

George Walter is the environmental program manager at the Nisqually Indian Tribe’s natural resources department; he also has a 40+ year interest in bird watching. He may be reached at george@theJOLTnews.com