This is Bird Note. In the late 1950s, scientist and

ornithologist Kenneth Stager set out to answer once

him for all, a question that had been argued over for decades.

Do vultures detect carrion by sight or by smell?

The story goes that his light bulb moment came when a union oil

employee told him of vultures congregating at the

spots along the pipelines where gas leaks were occurring.

And why would they do that? Well, because a key ingredient in the

odor of carrion is Ethelmer Captain, the same substance

companies added to odorless natural gas in their pipelines so

they could smell if there was a leak.

With just about the keenest sense of smell in nature,

turkey vultures can detect this odor in the air at even a few

parts per trillion. So Stager rigged up a

mercaptain emitting machine, took it into the field and

recorded his results. Definitively, he proved that

vultures find their prey because of its smell.

Today, there are more sophisticated ways to track pipeline leaks,

but who knows? Now and again, a watchful worker may just cast

an eye upward on the lookout for ominous silhouettes,

slowly circling against the blue sky.

For Bird Note, I'm Mary McCann.

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