Billions of US birds are migrating sooner due to climate change, study shows

Hundreds of species of birds are migrating earlier in the year than they did 20 years ago, according to a new study – and it's all down to climate change. US researchers used AI and big data to crunch 24 years of radar data on the night-time migratory behaviours of hundreds of bird species - representing billions of birds in total. They found that birds that have synchronised their migration with the availability of food - which is influenced by climate change - now find their migratory clock out of kilter. Temperature and migration are so closely aligned that the greatest changes in migration timing occur in the regions of the US that are warming most rapidly. The changes were more pronounced during the spring migration than in the autumn, as birds rush to reach breeding grounds and find mates before they are'crowded out' by competitors.