Researchers at Sheffield University say they have established that the reason birds have started to sing at night rather during the day is because of high noise levels, according to a BBC report. Previously it was argued that the cause was levels of light pollution in urban areas.
The team researched the behaviour of robins. Aptly-named researcher Robin Fuller told the BBC:
“We went out and measured both noctural light and daytime noise levels and we found that daytime noise had a far stronger effect. We found that night-time light had a small effect, but very much smaller than the impact of noise levels.
“The birds appear to be singing at night to avoid competition with high noise levels caused by our cities during the day. Noise levels were 10 times higher in places where birds were singing at night.”
The research is published in the Royal Society of the Arts journal Biology Letters.