In the city, the great tit prefers its sense of smell to find food despite pollution, while in the fields it relies more on sight, according to a study that highlights the bird’s ability to adapt to urban environments.
“This is the exact opposite of what we expected, a real surprise,” Diana Rubene, a behavioral ecology researcher at Uppsala University of Agricultural Sciences in Sweden, told AFP.
Parus major, the largest of the tits, is also one of the rare sparrows that have colonized cities without denying their rural connections.
The bird uses both sight and smell to identify a wide variety of foods—seeds, earthworms, a range of insects, and so on. An added benefit for the scientist is that he is a fast learner.
How does this bird use olfactory and visual feeding cues, a combination or not? And does the urban environment, with its lighting and pollution, influence his behavior?
A team of researchers from the Uppsala University of Agriculture and Lund University of Biology trained thirteen great tits to find food in the form of small pieces of earthworms hidden in a group of perches.
The collection placed on the perch offered the bird a choice of a perch without a distinctive and empty sign, another with a colored ball, a third with a sachet that emits an odor, and a fourth with a combination of color and smell, for example, blue and vanilla.
Great Tit in Troitsky near Moscow, January 14, 2018 in Russia (AFP – Yuri KADOBNOV)
Loving little caterpillars that feed on tree leaves, Parus major uses its eyesight as well as its exceptional sense of smell to find them. It identifies chemical signals – volatile compounds – emitted by trees attacked by a caterpillar.
“We expected that an urban environment with a lot of pollution and other unnatural odors could cloud the birds’ sense of smell and make it difficult to use,” explains Diana Rubene. “But the conclusion is the opposite.”
– “Cleverer” –
“Urban” tits caught in two areas of the city of Lund preferred perches equipped with an odorous signal. On the contrary, field tits caught in the forests preferred visual signals.
Great Tit in London, July 6, 2022 (AFP/Archive – Daniel Leal)
The study, published Wednesday in the British Royal Society’s journal Open Science, suggests, among other things, that the relative lack of vegetation in cities makes it easier for chickadees to distinguish signals from insect-bearing trees.
This remains a hypothesis, according to Diana Rubene, who readily admits that the role of smell in the sensory arsenal of birds remains to be deciphered.
It was his research that was originally aimed at determining whether the tit supports the association of visual and olfactory signals. In fact, it shows that, according to the researcher, “there is no real evidence that this solution is more attractive” than a simple signal. In other words, combining two signals does not provide any real added value.
But this is only true for the entire test population, because there is a difference between the sexes. And this is the third discovery.
Females tend to preferentially use one combination of signals without neglecting others. For what? Because, according to the Swedish researcher, they are “more motivated and more focused.”
Great Tit in Troitsky near Moscow, January 14, 2018 in Russia (AFP/Archive – Yuri KADOBNOV)
The females maintained during training that this signal association was also a promise of reward. So they are used when males flutter from one perch to another.
A matter of survival, physically weaker and persecuted by males when they compete with them for food in winter, “females must be smarter”.