Cuckoo populations have declined severely across the UK and Europe. Understanding migratory bottlenecks and habitat loss is key to reversing their decline.
Individual cuckoos face high mortality during migration with satellite data showing many birds dying during the Sahara crossing. Conservation welfare extends beyond individual suffering to population-level concerns about extinction risk. Cuckoos depend on good insect availability — especially hairy caterpillars that most birds avoid — for fuelling migration. Both habitat-scale management in the UK breeding season and international conservation at African wintering sites are needed. BTO tracking data provides unprecedented insights into mortality points.