Females of titmouses living near roads and human settlements have to change their sexual habits: they usually prefer low-lying males, but industrial noise makes them deal with those who sing high, but audibly.
The influence of human civilization on living nature is expressed not only in the chemical contamination or disappearance of habitual habitats for animals. Researchers from the University of Leiden (the Netherlands) decided to test how the noise pollution affects the behavior of birds.
We are used to the noise of the city, industrial production, roads, and the impact of noise "dirt" on the environment for us is not too obvious. Nevertheless, industrial-urban sounds, which are grouped mainly in the low frequency zone, can interfere with the communication of animals and birds, thereby affecting their behavior and ecology. In previous studies, ornithologists from the Netherlands have shown that road noise makes the males of the big tit (Parus major) literally increase their voice - singing at higher frequencies. In the new work, scientists find out how much this increase in tone affects the behavior of birds.
Ornithologists recorded songs of 30 males, which they perform at dawn during the spring mating season. Analysis of vocal exercises allowed to conclude that the lowest-frequency songs males perform directly for females ready to lay eggs. After the chicks were out, the researchers checked which of the males had their own nestlings in their nests, and which ones were fooled. It turned out that the higher the male's marriage song, the more likely it was that the female would escape from him on a date with the new knight, and the nestlings in the nest would be the offspring of the latter.
Thus, female tits (like many women?) Are female fans with a sexual baritone. In the third variant of the experiment, the authors suggested listening to the females, hiding in their nests, recording the voices of the males. The females preferred low songs, but if low-frequency noise was imposed on the recording, they had no choice but to answer high voices. The results of their observations were presented by scientists in the journal PNAS.
Thus, male tits, living near a person, have to make a difficult choice: if they sing sexually and low, they may simply not hear, and if high - there is a chance that they will prefer another. Females also have to somehow change their behavior, choosing not the one you want, but the one you hear.
In this case, as the researchers write, the tits are lucky: they can vary their songs in height. How, in this case, behave those who have not endowed nature with such a plastic voice, as fatal on their ecology affects the noise pollution - has yet to be studied. But it can be assumed that the fate of such species, which also managed to be near a city or highway, is quite unenviable.