The effects of weather

R. J. O’Connor & R. A. Morgan: Some effects of weather conditions on the breeding of the Spotted Flycatcher Muscicapa striata in Britain
Bird Study, 29:1, 41-48

This study used annual nest record data for the years 1961-1980. Laying was early in years when May was warm and was late when May was cool. Rainfall and sunshine hours in May had no effect on laying date but clutches were significantly larger if the month was sunny and were smaller later in the season. Nestling success in June was significantly higher in warm sunny conditions.