Hummingbirds Can Smell

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Contrary to popular belief and studies on some hummingbird species, hummingbirds apparently have an active sense of smell.

We have known for some time that New World Vultures have an excellent sense of smell, as do many seabirds (Procellariformes). This is due in part to their large olfactory bulbs-rounded mass of tissue that contains several types of nerve cells that are involved in the sense of smell.  The olfactory bulbs receive information about smells from the nose and send it to the brain by way of the olfactory tracts. The size of the olfactory bulbs in hummingbirds is about half that of seabirds and slightly less than that of Rock Pigeons.

However, hummingbirds’ olfactory bulbs are extremely small. Previous studies indicate that the birds did not have a preference for different smelling flowers. Bird-pollinated flowers generally do not have a strong scent, unlike insect-pollinated flowers which generally do.

World Migratory Bird Day | Rufous Hummingbird (Selasphorus r… | Flickr
Rufous Hummingbird

In a recent paper in Behavioral Ecology and Sociobiology entitled What is that smell? Hummingbirds avoid foraging on resources with defensive insect compounds in which the authors present evidence that hummingbirds avoid some flowers with defensive chemicals in order to make foraging decisions and avoid conflict with potentially dangerous insects at a flower or feeder. For their experiments, the researchers allowed more than 100 hummingbirds in the field and laboratory to choose between two feeders, either sugar water alone, or sugar water plus one of several chemicals whose scent signaled the presence of an insect. There were no visual differences between the two feeders offered in each of the experiments.

Tests included the scent deposited on flowers by European honeybees, an attraction chemical secreted by Argentine ants, and formic acid, a defensive compound produced by some Formica ants which is known to harm birds as well as mammals. So it’s not the smell of food, nectar, that attracts hummingbirds, but the presence of defensive chemicals that demonstrate that hummingbirds do have a sense of smell, at least for certain substances.

From Science Daily: “Recent behavioral studies have shown that some bird species use their sense of smell to navigate, forage or even to distinguish individuals. Silke Steiger at the Max Planck Institute for Ornithology and her colleagues chose a genetic approach for their study. Their research focused on the olfactory receptor (OR) genes, which are expressed in sensory neurons within the olfactory epithelium and constitute the molecular basis of the sense of smell. The total number of OR genes in a genome may reflect how many different scents an animal can detect or distinguish. In birds such genetic studies were previously restricted to the chicken, hitherto the only bird for which the full genomic sequence is known. They found considerable differences in OR gene number between the nine bird species. The brown kiwi from New Zealand, for example, has about six times more OR genes than the blue tit or canary.”

So genetic studies may solve this question eventually.

12 thoughts on “Hummingbirds Can Smell”

  1. great information, perfect presence. i’ve got 2 questions: is rock pigeon the same rock dove? and what difference is principally there between dove and pigeon?

  2. Rock pigeon and rock dove are the same bird. There is no biological or taxonomic difference between pigeons and doves. The names were just derived from different languages.

  3. Ellen Slanczka

    Amazing how for so long it was believed hummingbirds didn’t smell. With that said, I’m wondering if a hummingbird would be able to smell a skunk? Does skunk musk have the same chemical makeup a hummingbird would avoid?

  4. We have ants getting into the feeders which are on the windows. The ants avoid Vicks Vaporub rubbed on the window surface. Would that smell also keep the hummers away?

  5. Our 3 hummingbird feeders were really mildewed so I washed them using dawn and chlorox in the water. I throughly rinsed them after scrubbing with a toothbrush.
    The feeders are very standard, with glass and red plastic. The sugar water is 4 parts water to 1 part sugar. The feeders have been back up all afternoon, but there has been no hummer activity. ????

    1. This is the time of year that birds begin to migrate so they move around and the birds that previously know of your feeder are probably no longer around.

      Also, climate change has prompted many species of birds to change their migratory timing. There have been reports of an unusual increase in Ruby-throated Hummingbirds in Gulf Coast areas already this year, meaning birds from the north are arriving earlier.. There could be other reasons but I suspect climate change has affected their timing.

      1. We are in East Tennessee. It is the end of August and we always have hummingbirds feeding through September.

  6. Thanks for the hummer info.
    Also if one Does research on sugar water mixture,
    You will find that you boil filtered water and mix three parts sugar to one part water.


  7. We recently have been having what I think is bats hitting our feeders at night. They drink whatever they can but mostly spill the nectar out of the feeders. I’ve washed the feeders and refilled them with nectar but they aren’t liking the feeders now. Hence I searched if they can smell. I’ve thoroughly washed all again and will try again. It’s been extremely hot and I’m sure they need the food and fluids.

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