Monarch butterflies have been tracked soaring high to make use of strong tailwinds on their long-distance migration
Every September an incredible migration phenomenon begins. Clouds of stripy orange monarch butterflies set off on a 2,500km journey, travelling from southern Canada to warmer climes in southern California and Mexico. Come spring they follow the milkweed blossom and travel back up north. No butterfly completes the entire trip: after flying many hundreds of kilometres the female butterflies lay eggs and pass the baton to the next generation. Now a new study, published in Biology Letters, reveals how these amazing insects make use of the weather to aid their journey.