Do vultures detect carrion by sight or by smell? The lightbulb moment came to ornithologist Kenneth Stager when a Union Oil employee told him of vultures congregating at the spots along pipelines where gas leaks were occurring. Why would they do that? Because a key ingredient in the odor of carrion is ethyl mercaptan — the same substance companies add to odorless natural gas in their pipelines, so they could smell if there was a leak. So now we know that vultures can spot carrion by either sight or smell.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.