Cuckoo Migration Welfare: Tracking Long-Distance Travellers

Cuckoo populations are falling across the UK. Satellite tracking has revealed the extraordinary welfare challenges they face on migration to Africa and back.

Key Facts

UK cuckoo populations declined by around 65% between 1981 and 2018
Satellite-tagged cuckoos reveal two distinct migration routes - west via Iberia or east via Italy
Western route birds have dramatically lower survival rates, linked to reduced food in sub-Saharan Africa
Cuckoos rely heavily on caterpillars, particularly hairy species avoided by other birds
The timing of their arrival in the UK is driven by caterpillar abundance on breeding grounds
Males arrive first, females up to two weeks later - a welfare-relevant phenological mismatch risk

Welfare Considerations

Cuckoo welfare research enabled by satellite tagging has revealed the specific points in their annual cycle where mortality is highest. The western migration route across West Africa involves crossing the Sahara during a critical fat-burning phase, and drought years reduce the refuelling opportunities that allow safe crossing. In the UK, declines in large hairy caterpillars - a food source the cuckoo is uniquely adapted to exploit - reduce breeding condition. Supporting the BTO's cuckoo tracking project directly generates welfare knowledge.

What You Can Do

Donate to the BTO's satellite-tagged cuckoo project at bto.org/cuckoos
Support habitat management that maintains caterpillar-rich vegetation
Create habitat for large moth caterpillars by planting native shrubs and trees
Advocate for land management funding in African wintering areas through international charities
Report cuckoo sightings to BTO BirdTrack to help track arrival and distribution