Coming To Their Senses
Can birds smell or taste? It's an age-old debate.
By George Harrison, Contributing Editor
In all my time of studying birds, there's one topic that always elicits a reaction—when I say birds can't smell or taste.
I'm not surprised that many people have an opinion on this subject. After watching birds select only certain types of seeds, fruit and suet from backyard feeders, it's difficult to believe birds don't rely on smell or taste to determine what to eat.
Even the experts can't agree, despite more than a century of research and debate. The results of studies in this area are often contradictory or simply inconclusive.
However, one fact is almost certain. Birds depend less on the senses of smell and taste than people do.
Most birds have little use for the sense of smell. The odors of food, prey, enemies or mates quickly disperse in the wind. Birds possess olfactory glands, but they're not well developed in most species, including the songbirds in our backyards.
The same is true for taste, which is related to smell. While humans have 9,000 taste buds, songbirds have fewer than 50.
That means the birds we feed around our homes must locate their food by sight or touch, two senses that are highly developed in birds.
A Taste Test
Anyone who has used cayenne pepper in birdseed to discourage squirrels knows that birds will eat the seeds without hesitation. Why? Because birds don't detect the strong scent and taste of the pepper.
However, squirrels, like all mammals, have well-developed senses of smell and taste and react to the pepper as we would—with distaste.
Further evidence that birds find food by sight is an experiment I conducted with six wild birdseed mixes, each having a unique formula and a different appearance.
I presented the six mixes in two kinds of feeders, six tube feeders and six tray feeders. At the end of each day, I weighed and measured the uneaten seeds.
One mix was a clear winner, but what amazed me was watching the birds go right to the feeders containing the winning mix, even though I frequently rotated them. Obviously, they recognized the favored mix by its appearance.
Why they preferred this specific mix, however, is somewhat of a mystery. Since instinct plays a large role in their behavior, one possible explanation is the birds relied on their genetic programming to determine what seed was best for them. After all, birds are "built" to eat certain types of foods.
While most birds seem to lack much power of smell, there are some groups of birds that can locate food using their olfactory glands.
Extensive research into this subject has shown that vultures, seabirds, kiwis and parrots have well-developed olfactory glands, giving them some sense of smell and taste.
A biologist once watched as vultures found hidden meat by detecting its odor. Some seabirds can smell fish oils from a distance and kiwis in New Zealand are able to sniff out earthworms underground. But these are exceptions in the bird world.
Clearly, there is more to learn about this topic.
If birds can't smell or taste, why do they avoid eating toxic monarch butterflies? How do hummingbirds distinguish plain water from sugar water?
Maybe one day we'll learn the answers to these and other questions. Perhaps we'll even discover that a bird's olfactory glands play a role totally different from other members of the animal kingdom.