According to the U.S. Fish and Wildlife Service, some 55 million Americans feed wild birds in their yard or local park, spending a combined $3 billion on feed annually — which sounds like a bit more than tuppence a bag.
Among those who partake of this pastime is Hanover’s John Goldthwait, who reached out to the Curiosity Desk for help in answering a question he’s long had about our fine feathered friends.
“One of my hobbies is to feed the local birds,” he said. “And I’ve always wondered, do birds have a sense of smell?”
For answers to John’s question, I journeyed to the Mass Audubon Blue Hills Trailside Museum in Milton, where I met up with raptor specialist Norman Smith.
WATCH: Do birds have a sense of smell?
“It’s a very interesting question,” said Smith, who recently retired from his longtime role as the Trailside Museum Director. “And if you ask this question twenty-five or thirty years ago we would probably say no, birds probably don't have any kind of a sense of smell at all.”
But we’ve come a long way since the early 1990s. We now know that Pluto is not a planet. We know that Apple stock was a significantly better investment than Beanie Babies. And we know that most birds — in fact probably all birds — have at least some sense of smell.
Smith said there are a few reasons why the conventional wisdom that birds do not have much of a sense of smell held on for so long. For starters, he said, many birds are plenty happy to eat things whose smell we humans generally find off-putting to say the least — like skunks and dead animals.
“And it was because [birds] don't seem to have much of an olfactory gland in their brain,” he explained. “And the nasal passages, for the most part, are very small.”
But birds, of course, come in all sorts of shapes and sizes. And the same is true of those nasal passages, as Smith pointed out to me, specimen in hand.
“This is the skull of a turkey vulture,” said Smith, pointing to two large, ovular cavities at the base of the beak. “You can see the nasal passages right here, and you can see how large those are.”
Researchers also learned upon closer and more thorough examination that, just like those nasal passages, the olfactory bulb in a bird’s brain isn’t always so small.
And the same goes for the number of smell-related genes each bird species has. Kiwis, for example, have about 200 more of them than humans do.
So how well a bird can smell depends on the bird. And some can smell pretty darn well.
How our fine feathered friends actually use their sense of smell ranges, said Smith. Studies on little ground foragers called juncos have shown that smell helps them mate. Homing pigeons use it to help them navigate. And for tube-nosed petrels and many vultures, it helps them find food.
And speaking of vultures, Smith said they are among the very best smellers in the bird kingdom. So good that they get put to work, so to speak, up in America’s 49th state.
“When I was in Alaska, I was talking to guys about how they find leaks in the natural gas pipeline. And they said they use birds,” said Smith. “When [they] have a leak in the natural gas pipeline [they] look and see if there are any vultures circling around the pipeline…That methane smells like dead animals, so these vultures, when they congregate around…that’s where the gas leak is.”
Still, other birds, even common ones like hummingbirds, remain something of a mystery.
“Do the hummingbirds actually use a sense of smell when they're migrating? Or do they use it to find flowers? I mean, flowers give off an aroma,” said Smith. “But we really don’t know.”
In fact, what we still don’t know about birds and their sense of smell likely far exceeds what we actually do know. And that is just fine with Norman Smith.
“That's the exciting thing about research,” he said, “Because we find new things all the time. Research is really exciting, and you don't have to be a scientist to do research.”
If there is something you've been itching to know more about, email The Curiosity Desk or send in your question below. Edgar might just dig up the answer in a future episode. For more from The Curiosity Desk, follow Edgar B. Herwick III on Twitter and subscribe to the GBH News YouTube Channel.
