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As a budding ornithologist and bird lover, you decide to set up a little oasis in your backyard to attract tiny, winged visitors. You do some research beforehand on the preferred food of the species you’d like to attract and stock your new feeders with a variety of seeds and nuts. But how do the birds know that you have filled their feeder? Do they have a sense of smell as keen as a dog or do they rely on their other senses to find food?
In short, it depends on the species and the size of their olfactory bulbs. Indeed, recent studies have shown that birds have a fully functional olfactory system, and some species rely heavily on their sense of smell for many tasks, such as foraging, predator avoidance, mate selection, nesting strategy, and other activity patterns. Thus, it appears that birds can use their sense of smell as much as their sight and hearing to find the seeds you just put in their feeders.
Contrary to what scientists believed until the second half of the 20th century, birds have a more developed sense of smell than expected and are able to use olfactory information to perform certain tasks, such as foraging.
Indeed, previous research has shown that only certain large species had a keen sense of smell, such as turkey vultures, petrels, kiwis, albatrosses, penguins, ducks, and geese.
However, since the 1960s, research work carried out on several avian species has demonstrated that the olfactory structures of these are more complex and that olfaction plays a more important role than expected in much smaller species. Thus, species frequently encountered in gardens and farms, such as starlings, garden warblers, robins, hummingbirds, pigeons, quails, turkeys, and chickens, appear to have the ability to use their sense of smell to locate their food.
Nevertheless, it is still generally believed that birds’ sense of smell is less developed than that of reptiles and mammals. Moreover, while it has been demonstrated that the sense of smell plays a key role in the navigation of seabirds over long distances, there is not enough evidence to determine whether all the small species that come to your feeders do this solely through their sense of smell.
Birds locate their food primarily through their exceptional vision; some species are even known to have the best eyesight in the entire animal kingdom. Thus, sight plays a crucial role in the survival of these animals, although not all species benefit from the same visual acuity.
On the one hand, if the structure of their eye is similar to that of mammals, birds however have a tetrachromatic vision, meaning they see four colors: UV, blue, green, and red. Mammals, on the other hand, are trichromats and can only distinguish between blue, green, and red.
Also, the eyes of birds are generally larger, proportionally, than those of mammals, implying a greater density of nerve cells. These anatomical particularities give birds fine visual acuity, more panoramic vision, and better ability to detect movement.
In other words, birds visiting your garden know you’ve filled the feeders because they can see the seeds just by hovering over them. Plus, if other birds are already feasting happily on these delicious foods, newcomers will quickly detect these movements of excitement. And once they learn where to find food, they keep coming back to the same spot for more!
Also, birds use their second most important sense for finding food sources, which is hearing. Their ears are funnel-shaped and covered with soft feathers to protect them. Thus, when a group of birds is pecking seeds, they can emit different sounds, songs, and calls, which will serve to alert their congeners that a feast awaits them in your garden!
If you’ve never had a feeder, it’s normal for the birds to not come right away the first time you fill it. Be patient; all it takes is for a bird to fly over the feeder and start pecking at the seeds with cries of joy for its congeners to be quickly warned!
Sunflower seeds please the vast majority of birds. Then comes corn, white millet, canary seed, peanuts, safflower, and rapeseed. However, commercial mixtures are not recommended, because they cause a lot of waste: the birds reject most of the seeds that they do not like.
In addition, you can present your different seeds in separate feeders or prepare mixtures according to the tastes of the species you want to attract. Depending on the season, adjust your mix to please your favorite birds. You can also find a wealth of detail on the food preferences of different bird species in ornithology books.
Birds know when you fill the feeder because they rely on their excellent vision and keen hearing. Whether the species that visit your garden can also rely on their sense of smell to locate seeds is still up for debate, but at least we now know for sure that most birds have a much more complex olfactory system than we thought.
Featured Image Credit: Yanna Zissiadou, Unsplash
Genevieve is a biologist and science writer and has a deep love for capuchin monkeys, pumas, and kangaroos, which has taken her around the world to work and volunteer for several wildlife rehabilitation centers. A Canadian expat, Genevieve now lives in Argentina, where she wakes up every morning to horses and cows saying hello from the vast plain next to her home office window. Having the privilege of sharing her knowledge and passion for animals of all kinds is what makes her fulfilled and happy.
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