09.09.2022: Sight, smell or both? How birds find their way back to a feeding site was the subject of a recently published study conducted by a team of researchers at the University of Veterinary Medicine Vienna. The researchers observed great tits and were able to show that olfaction is an essential tool for finding one's way, even in familiar surroundings. These findings highlight that in birds the sense of smell is indeed more important for orientation than previously thought.

The great tit (Parus major) is a common songbird with a wide distribution range. It is a welcome guest at birdfeeders in winter and therefore focus of a  recently published study. A team of scientists tested whether great tits use odours from the environment to find their way back to feeding sites. The researchers captured the birds and in some of the individuals, they briefly dampened their sense of smell by rinsing their noses with zinc sulfate. Afterwards, all birds were released - some in the immediate vicinity and another subset of the animals was let go at a distance of 1.5 km.

Great tits with unaltered olfactory capacity returned more quickly to their home range

Both, the great tits with a reduced sense of smell and those with a normal sense of smell found their way back to the feeding sites. "This result did not surprise us at first, as we deliberately released the birds within their familiar environment," explains study first author Katharina Mahr from the Vetmeduni's Konrad Lorenz Institute of Ethology. "It is interesting, however, that birds with a diminished sense of smell needed significantly more time to return. This effect is pronounced when the birds were released at a greater distance. Our results indicate that odours serve as an important source of information for orientation in a familiar environment, despite the existence of visual cues."

A good sense of smell helps to optimise foraging efficiency

According to the researchers, certain smells and scent cues in the familiar environment could serve as a reliable source of information for finding one's way around. “Similar results have already been obtained for migratory birds. But especially for species such as great tits, which often overwinter in breeding areas, orientation and navigation by means of smell could help to optimize foraging in times with little food supply, for example in the winter,” says last author Herbert Hoi, also from the Vetmeduni’s Konrad Lorenz Institute of Ethology. According to Hoi the results of the study strongly emphasise that olfaction might be of greater importance for the orientation of avian species than previously thought, thereby contributing to the understanding of the functional contexts of smell in avian life.

Chemistry in the air

Airborne chemicals function as sensory cues for many organisms, and their use in navigation may be one of the most important evolutionary mechanisms that explains the development of olfaction in animals. Despite solid evidence for the importance of olfaction in avian life – for example, in foraging or mating – the importance of chemical cues for avian orientation remains largely debated. Olfaction in songbirds is, despite their remarkable orientation skills, surprisingly understudied.

The article “Songbirds use scent cues to relocate to feeding sites after displacement: An experiment in great tits (Parus major) by Katharina Mahr, Linda Nowack, Felix Knauer, and Herbert Hoi was published in Frontiers in Ecology and Evolution.

Scientific article