WARMER springs create a mismatch where hungry chicks hatch too late to feast on abundant caterpillars, new research shows.

With continued spring warming expected due to climate change, scientists, including experts at Durham University, say hatching of forest birds will be “increasingly mismatched” with peaks in caterpillar numbers.

Researchers used data collected across the UK – largely by citizen scientists – to study spring emergence of oak tree leaves and caterpillars, and timing of nesting by blue tits, great tits and pied flycatchers.

They also tested a theory that some bird species in southern Britain may suffer most due to a greater mismatch effect – but they found no evidence of this.

The findings, published in the journal Nature Ecology and Evolution, suggest that as springs warm in the future, less food is likely to be available for the chicks of insectivorous woodland birds, unless evolution changes their timing of breeding.

The team was led by the RSPB and the universities of Exeter and Edinburgh, and included research at Durham University.

Professor Steve Willis, in the department of Biosciences, Durham University, said: “Woodland birds start to nest in anticipation of the timing of trees producing leaves, and of caterpillars emerging to eat the leaves.

“Our work suggests that birds are tending to mistime their nesting as springs become warmer, such that they miss the peak of caterpillar prey to feed their young.

“Across 200 nestboxes that we monitor in woodlands around Durham, timing of breeding by blue tits is relatively consistent across different years, but the timing of oak leafing varies, being earlier in warmer years.

“It is difficult to know how this year’s blue tit nests will fair, given the late wintry weather and the recent fine weather this spring, but in recent years warmer springs have typically resulted in a mismatch between chick demand and caterpillar availability, sometimes resulting in very low numbers of chicks fledging.”