Bluebirds apparently 'shout' to be heard over the noise made by us loud humans.
A study by the University of Exeter has found their songs become louder and lower pitched as soon as noise levels rise.
It wasn't clear before whether birds could make vocal adjustments in real time, but the skill has now been observed in five different species.
Behavioural Ecologist, Dr. Caitlin Kight led the study:
"Although many manmade noise regimes are often very different from those found in nature, there can be surprising similarities in certain features, including volume, pitch, or timing. Sounds caused by traffic, for example, may not be hugely different from those produced by waterfalls or heavy winds. Animals that evolved in habitats with those natural features may therefore already have, within their existing repertoires of behaviours, the flexibility to respond to noise pollution. This certainly seems to be the case with bluebirds."
