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Paris Became Quieter, but Great Tit Songs Stayed at a Higher Pitch

A great tit singing from a tree branch
Research · Behaviour

Paris has become quieter in recent years, but the songs of its urban great tits have not shifted back towards the lower frequencies heard in nearby forest. A study published in Ornithological Applications on 16 February 2026 found that the city birds still sang with higher minimum frequencies than birds in Fontainebleau in 2023, while their minimum song frequency in Paris had not declined since 2003.

Traffic and other human activity produce much of their sound energy at relatively low frequencies. That can mask parts of birdsong, making signals harder for other birds to hear. Many birds living in noisy places sing at higher frequencies, where their notes overlap less with the low-frequency background. The great tit (Parus major) is a well-studied example, and its varied, repeated songs make it useful for examining how animal communication changes across urban environments.

Daniel J. Mennill and Hans Slabbekoorn compared recordings made two decades apart. In both 2003 and 2023, they recorded free-living great tits at noisy sites within Paris and at quieter forest sites near Fontainebleau. Directional microphones captured the songs, while calibrated sound measurements described the immediate acoustic environment. The researchers also examined long-term monitoring data on noise in Paris.

Spectrograms comparing great tit songs recorded in urban Paris and Fontainebleau forest
Examples of great tit songs recorded in urban Paris (left) and Fontainebleau forest (right) in 2023. The city examples generally begin at higher minimum frequencies. Figure 2 from Mennill & Slabbekoorn (2026), Ornithological Applications, CC BY 4.0.

In 2003, the researchers recorded 27 individuals in Paris and 48 in Fontainebleau; in 2023 they recorded 57 urban and 30 forest individuals, with more than one song type analysed from some birds. The repeated city–forest comparison allowed them to ask whether the acoustic difference had narrowed as Paris became quieter.

Paris noise fell by 3.1 dB, but song frequency did not

Government monitoring at 12 Paris sites showed that average anthropogenic noise fell from 69.3 dB(A) in 2008 to 66.2 dB(A) in 2023. Because the decibel scale is logarithmic, that 3.1 dB decline corresponds to roughly half the sound intensity. The bird recordings nevertheless showed a persistent difference in 2023: minimum song frequency averaged about 3.54 kHz in Paris and 3.26 kHz in Fontainebleau. Minimum song frequency in Paris had not declined significantly between 2003 and 2023.

Box plots comparing minimum great tit song frequency in Paris and Fontainebleau in 2003 and 2023
Minimum song frequency in urban Paris and Fontainebleau forest in 2003 and 2023. The 20-year comparison showed no significant decline in either habitat. Figure 5 from Mennill & Slabbekoorn (2026), Ornithological Applications, CC BY 4.0.

Local background noise remained associated with minimum frequency in 2023

Background noise remained associated with song structure at individual recording sites. In 2023, songs recorded against louder background noise had higher minimum frequencies in Paris, and the same relationship appeared across the much quieter and narrower noise range in Fontainebleau. Songs also had narrower bandwidth — a smaller span between their lowest and highest frequencies — in noisier surroundings, while song duration showed no clear relationship with noise. These patterns are consistent with acoustic adjustment to the local sound environment. However, the broader historical comparison did not show a corresponding downward shift in Paris minimum frequency as average city noise declined.

The study could not identify why the urban song pattern persisted

A quieter city did not produce an immediate return to forest-like birdsong. The authors note that the Paris recording sites were still about 15 dB louder than the forest reference sites in 2023, so a larger reduction in noise may be needed before lower-frequency songs become advantageous again. They also raise a cultural explanation: young great tits learn from adult tutors, and decades of high urban noise may have left relatively few local tutors using lower-frequency songs. The study did not distinguish between these possibilities.

Sources and image credit

  1. Mennill, D. J., & Slabbekoorn, H. (2026). Acoustic differences persist in urban Parus major (Great Tit) over two decades of declining anthropogenic noise in Paris, France. Ornithological Applications, 128(2), 1–8. https://doi.org/10.1093/ornithapp/duag020Primary peer-reviewed open-access article published 16 February 2026 under CC BY 4.0. Recordings from urban Paris and Fontainebleau in 2003 and 2023 were combined with long-term Paris noise-monitoring data.

Image: Buchstapler — singing great tit (Parus major), photographed 22 March 2019; representative species image, not a bird from the study. Source: Wikimedia Commons. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

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