The smell of songbirds – wissenschaft.de

They have keen eyesight, but to what extent do songbirds also use their sense of smell to orient themselves? An experimental study now shows that large breasts, which do not smell, have relatively difficulty finding their way in their home environment. The scientists say the findings suggest that the sense of smell has been underestimated in songbirds.

Seeing, hearing, tasting, feeling and smelling – with these “antenna systems” animals get vital information about their environment. Depending on the species, some senses are known to be more or less important. Our sense of sight and hearing are especially important. On the other hand, the sense of smell plays a prominent role in dogs and many other animals. However, studies have already shown that in humans and animals, several senses often contribute to an overall picture of an impression. In this context, researchers led by Katharina Maher of the Konrad Lorenz Institute for Comparative Behaviorology in Vienna are now turning their attention to birds.

Do songbirds use scents as evidence?

For a long time it was assumed that smell did not play any role for this group of animals. But this has already been clearly refuted: numerous studies have shown that the perception of the presence of substances in the air is of great importance for many species of birds when searching for a mate, the perception of danger and also for orientation. For example, it has been shown that birds and migratory pigeons are guided by olfactory information, among other things, when orienting themselves over long distances. However, relatively little research has been done on the role of birds’ sense of smell in orientation – Mehr and her colleagues say this is especially true for songbirds. Do they only use their sense of sight to orient themselves in their traditional environment, or do scents play a role as well?

Researchers investigated this question by examining one of the most famous songbirds in our native bird world. The big nipple (Parus major) is also at home in urban areas and is a frequent guest at feeding stations in gardens, especially in winter. So this species was well suited to checking if songbirds use environmental odors to find their way back to feeding sites. For the study, the team captured a total of 112 large tits at feeding sites in their traditional habitats. Then only half of the birds’ sense of smell was anesthetized by zinc sulfate treatment. This effect lasts for a few days, but does not leave permanent damage. The researchers then released some birds at a distance of 400 meters from the captivity site – another group was released at a distance of 1.5 kilometers.

Scented birds find their way back faster

First of all, the obvious critical importance of the sense of sight became apparent: eventually the same number of large tits with a disturbed sense of smell as the control animals returned to the feeding stations. “This finding wasn’t really surprising because we left the animals in their familiar environment,” Maher says. However, birds with impaired sense of smell returned to feeding stations significantly later, as evidenced by evaluations. The fact that the sense of smell clearly affects the ability to orient is also reflected in the disproportionately increased delay in some test animals: “The effect was particularly evident when the birds were released at a greater distance,” Maher said.

From these findings, the researchers concluded that the sense of smell is not the critical factor, but rather an important component of the orientation system: “Our results suggest that odors in a familiar environment act as an important source of information for orientation, despite visual cues,” Maher says. The exact sources of information that birds use to sniff their way is still unclear. But there is a lot in the air that can also act as a guide based on the gradient of concentration.

Originally, similar results were obtained in migratory birds. But especially for species such as large tits, which often stay in breeding grounds in the winter, guiding and navigation by smell can help to improve foraging at times when food supply is in short supply, for example in the winter, as Says senior author Herbert Hoi of Konrad-Lorenz – Institute for Comparative Behavioral Research. According to him, the study underscores the often underestimated importance of the bird’s sense of smell: for many bird species, this source of information can also be of greater importance for orientation than previously thought.

Source: University of Veterinary Medicine, Vienna, specialist article: Frontiers in Ecology and Evolution, doi: 10.3389/fevo.2022.858981

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