birds sing high in modern life
A study has been released that shows how songbirds in numerous urban environments now sing higher than they used to. This has been shown for the first time to happen in multiple urban
locations, on a population-wide basis.
Researchers at Leiden University in the Netherlands observed the birds are adapting to increasingly pervasive noise pollution levels in the mid to lower frequency bands.
The sound of the great tits (they're birds!) were recorded and analyzed in 10 European cities. It has been shown that the younger birds are now learning to sing higher notes and are leaving out the lower notes altogether.
You can hear it for yourself on New Scientists' site:
the isolated song
the urban song
the forest song