Warmer springs can lead to a food mismatch that leaves young birds starving. The chicks hatch too late, so they miss an abundant supply of caterpillars.
Researchers said that as spring warming continues as a result of climate change, hatching of forest birds will be increasingly mismatched with peaks in caterpillar populations.
In a new study, Malcolm Burgess, of the University of Exeter, and colleagues used data collected by citizen scientists to study the emergence of oak tree leaves and caterpillars, as well as the timing of the nesting of three species of birds namely the great tits, the blue tits, and pied flycatcher.
They found that the hatching of the chicks is increasingly becoming mismatched with the emergence of their primary food: oak caterpillars, which are only active for a few weeks before they transform into moths.
The researchers, in particular, found that the Great tits hatch an average of two days later than the caterpillar peak. The Pied flycatchers emerged 13 days too late and the Blue tits typically hatch three days later.
"Forests have a short peak in caterpillar abundance, and some forest birds time their breeding so this coincides with the time when their chicks are hungriest," Burgess said.
The researchers said that the findings suggest that as springs warm in the future, there would likely be less food available for chicks of insectivorous woodland birds unless they would evolve and change the timing of their breeding.
"Temperate forest birds will become increasingly mismatched with peak caterpillar timing," the researchers wrote in their study.
"Latitudinal invariance in the direction of mismatch may act as a double-edged sword that presents no opportunities for spatial buffering from the effects of mismatch on population size, but generates spatially consistent directional selection on timing, which could facilitate rapid evolutionary change."
Climate Change And Food Supplies
The findings provide additional evidence of the unwanted impacts of a warming world on wildlife. Other species also suffer from dwindling food supply because of climate change.
A study published earlier this month in the journal Science, for instance, shows that heat from increasing global temperature affects life on the water surface making marine food chains less productive, reducing the number of fish in the sea.
A 2017 study also showed that a critically endangered species of lemur are starving as climate change and extended dry season disrupt the growth cycle of bamboo, their main food.