This morning I was listening to the wood pigeons calling from the trees across from my flat. But one of the things that struck me was that when a car approached or the local school's air conditioning units fired up, the birds would stop calling. They'd go quiet, but then as background noise reduced, they began calling again.
This was just a personal observation over a 20 minute period, so it could simply be a correlation with no cause and effect in play.
Studies have shown that birds are affected by noise pollution, but have you ever noticed this behaviour in wood pigeons or other species?