# Bird call/song adjustment to the physical environment

Do birds alter their calls/songs when they are in open areas vs in closed areas (e.g., grassland vs forest)?

This kind of habitat based response is seen a lot in active sensing animals (bats emit louder calls in open spaces, and also increase call duration) - but the 'selection pressure' to optimise echo detection is intuitively high.

I know birds alter their calls and song in the presence of natural and anthropogenic noise (Lombard effect), but I haven't found any studies looking at short term alterations in bird vocalisation to the physical environment.

Note: I am not referring to geographic/evolutionary patterns of bird song with physical habitat, but rather short-term, reversible alterations in song/call behaviour that individuals show.

• I smell a cool paper idea... Jul 7 at 7:44

Here, I recall one of the classic papers on Sound Attenuation and physical constrain (Wiley and Richards, 1970). Flat frequency sounds are advantageous for their low attenuation rate in open landscapes and high frequency-modulated sounds are advantageous in close forests where sounds get more resistance. Bird calls evolved in such a way that forest-dwelling birds have high-frequency modulation whereas grassland birds tend to have flat frequency vocalisations (Boncoraglio and Saino, 2007). There are birds who use multiple call types depending upon purpose and physical situations. It will not be impossible for them to use different call modulation based on the physical environment. Therefore, it can be a nice domain to explore.