The importance of moth caterpillars for common garden birds has been revealed in a new study. Researchers have found that years when moth numbers were up resulted in increased population growth for the blue tit.

The results, derived from 23 years worth of bird and insect population data, are published today in Ecology Letters.

Dr. Luke Evans, of the University of Reading, led the research. He said, “Insect abundance directly impacts songbird numbers from year to year. When moth caterpillars are large in number, blue tit parents can easily find food for their demanding chicks. When moth numbers crash it gets much harder for birds to find enough insects and raise as many young.”

Dr. Malcom Burgess, of the Royal Society for the Protection of Birds (RSPB), who co-led the research, added, “It’s important we understand the relationships between insects and birds to plan effective conservation measures given evidence of recent insect declines. Our study highlights the need to better manage habitats to support insects, as they are a vital food source sustaining many common garden birds such as the blue tit.”