RSPB found urban sparrow colonies waning at fastest rate where traffic-borne nitrogen dioxide was worst
The cheeky house sparrow is the archetypal city bird. You can find them around the world, but they are in serious decline in cities in Italy, Canada, India and the UK. London’s house sparrow population fell by 60% between 1994 and 2006.
Scientists from the Royal Society for the Protection of Birds fed London sparrows in 33 colonies and compared them with birds at 33 other places where no extra food was offered. More food meant more fledglings, but it did not improve their wintertime survival.