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How Developed is the Sense of Smell in Birds?

Dear Bird Folks,

I know birds have good vision and good hearing, but what about smell? Can hummingbirds smell sugar-water feeders? Can cardinals and chickadees smell a sunflower feeder from afar?

– K, North Eastham, MA

Oh, K,

I’ll answer your questions, but what is with your name? Is it really just the letter “K”? Really? Who’s your father, Mr. T? Is your mother The Divine Miss M? Whatever, I have to compliment you on your fine penmanship. I wish I could write like that. All through school they tried to teach me how to write in cursive, but no matter how hard I tried I could never do it. In fact, I was the one who put the word “curse” in cursive. You can look it up if you want, but I think you’ll find it’s true…much like your name is really just K.

It’s amazing how many creatures have the capacity to smell. Mammals, of course, can smell, but so can snakes, ants, bees and even fish (and I’m not talking about the fish you bought on sale from the back of a truck). But for some reason, birds’ ability to smell isn’t very well understood. To begin with, they don’t have a nose. Oh sure, there are those two tiny holes on each side of the beak, but those hardly count for a decent nose. And when was the last time you saw a bird sniffing anything? Rabbits, on the other hand, never stop sniffing. Dogs sniff everything and everywhere (sometimes in places I wish they wouldn’t). Even humans will sniff in the direction of a strong smell, especially if it’s smoke from a fire, or freshly cooked donuts, or even day-old donuts, or week-old donuts or the word donut (unless it’s written in cursive).

As you pointed out, most birds have superior eyesight and excellent hearing, but their sense of smell is thought to be lacking. However, recent studies have indicated that birds, at least some birds, use their sense of smell more than we first thought. Seabirds appear to have the ability to sniff out food that is miles away. Turkey Vultures, it is believed, can detect rotting food long before they can see it. New Zealand’s flightless kiwis hunt by probing their long beaks deep into the ground. With most birds, their nostrils (those two tiny holes) are located towards the back of the beak, up closer to the eyes. But such is not the case with kiwis. Their nostrils are positioned at the tip of the beak, leading to the notion that kiwis can actually sniff out worms and grubs, and lost change if they get lucky.

Some scientists take this smelling thing to a whole new level. They study birds’ olfactory receptors and even count the number of smelling genes birds have. But when it comes to backyard birds, you don’t need to take a gene count. You could actually perform your own study. I suggest you take a paper bag, fill it with sunflower seeds, close the top and place the bag outside in your yard, perhaps on a tree stump or picnic table. (You could also put on a lab coat and carry a clipboard, but those items are optional.) Then go back inside, pour a cup of coffee (for yourself, not the birds) and watch what happens. If your birds have the ability to smell seeds, they should, I would think, fly to the bag and attempt to open it. Birds such as crows, jays and woodpeckers certainly have the ability to hack through paper. Even tiny chickadees, which can chop into a tree in order to build a nest cavity, shouldn’t let a bag keep them from sunflower seeds…if they knew it was there. Without prejudicing your study, here is my prediction as to what will happen with your experiment.

I’m betting the birds will totally ignore the bag. Even if the bag has the name of my shop printed on it, they will ignore it (suggesting that birds not only can’t smell, but they can’t read either). Keep in mind that you’ll only have a short time to conduct your study. Eventually, a creature with a real nose (squirrel) will find the bag and tear into it like a kid with a piñata, and your experiment will be over (but the squirrel’s party will just be getting started).

Next, we should discuss hummingbirds, because if any bird would benefit from a sense of smell, it’s them. The fragrance of a blooming flower certainly has to be a hummer magnet, right? Actually, aroma doesn’t seem to make much difference to the birds. In fact, they tend to visit flowers that don’t have any smell. Once again, vision appears to be the key. This is why our hummingbird feeders are red. If red wasn’t so important, we could use green, brown or white feeders, or whatever color matches the trim on the house, and we would still get lots of birds. Don’t believe me? Try it and let me know what happens.

Here’s another thing. I have an ant guard above my hummingbird feeder. It’s in the shape of a bell and it works great to keep the ants out. The guard also happens to be bright red, so every new hummer on the block initially investigates it. They poke at it several times before eventually moving on to the feeder itself. If the birds could smell the nectar in the feeder, they wouldn’t waste their time poking at the ant guard. (I think that’s going to be my next bumper sticker: “Don’t poke the ant guard.” Everyone will be confused, but the hummingbirds will totally get it.)

Based upon my own primitive analysis, K, I think vision and not smell is the main factor to locating food, at least for our backyard birds. Researchers continue to study how all birds use their sense of smell, but so far obtaining broad proof has been difficult…but not nearly as difficult as writing in cursive. That’s impossible.