Bill size modulates avian song frequency and trill rate

Evidence

In birds, besides body size the dimension of the bill is a further important element to modulate sounds, especially high-frequency sounds. In fact, the change in bill size and its morphology are not only correlated with foraging habits and the structure of the habitat, but the suprasyringeal tract that functions as a resonating space is directly related to bill dimension and shape. Small bills can produce more modulations than large bills, and this morphological trait is negatively related with the trill rate. Smaller bills produce trills at a higher rate and definitively larger bills are less versatile and less able to produce sound than smaller bills. In particular, the bill is gaped more during the production of high-frequency notes, and the speed with which the bill is opened or closed depends on the dimension of the bill. Podos (1997), investigating 34 species of birds belonging the family Emberizidae, has found that the increase of trill rate corresponds to a reduction of frequency bandwidth utilized. — Almo Farina, Soundscape Ecology, 400

Categorization

• XREF: connects to: Traffic noise permanently raises song tonality in red-winged blackbirds — Almo Farina, Soundscape Ecology: Principles,…, 1384; Body size constrains the frequencies animals can vocalize — Almo Farina, Soundscape Ecology: Principles,…, 385

Broader Connections

• Body size constrains the frequencies animals can vocalize #expands (0.85) — Almo Farina, Soundscape Ecology, 385
• Traffic noise permanently raises song tonality in red-winged blackbirds #qualifies (0.80) — Almo Farina, Soundscape Ecology, 1384