Barn swallows are among the most familiar and beloved summer visitors to Britain but face growing challenges from climate change affecting both their UK breeding habitat and their sub-Saharan African wintering grounds.
Decline in aerial insect biomass caused by agricultural intensification and pesticide use means returning swallows find less food than historical populations. Late cold springs after early arrival cause birds to incubate on minimal food reserves. Drought in the Sahel strips fat reserves before the northward migration. Swallows that lose broods to weather events or prey scarcity late in the season cannot compensate with additional broods. The closure of traditional farm buildings removes the nesting sites to which birds return faithfully each year.