Barn swallows undertake one of Britain's longest migrations, with welfare challenges spanning breeding site availability, aerial insect prey abundance, and migration corridor hazards.
Barn swallow welfare reflects the dual pressure of declining breeding site availability and reduced aerial insect prey. Swallows are obligate aerial insectivores - they cannot switch to alternative prey if flying insects are scarce - making the widespread decline in insect biomass a direct welfare threat through nutritional deficit during both breeding season and migration. Breeding pairs that cannot find sufficient insect prey to feed growing chicks face chick starvation, and adults that arrive from Africa in poor condition after a long migration may not be able to recover body condition rapidly enough in impoverished insect environments. Nest site loss through farm building conversion removes access to traditional sites that families may have used for generations - swallow nest site fidelity means individuals return expecting sites that no longer exist. The migration journey itself presents welfare hazards: weather events that ground swallows over the Sahara or Mediterranean without food, collision with power lines and wind turbines, and hunting in some Mediterranean countries all cause welfare harm to migrating birds. Creating and maintaining appropriate nest sites in farm buildings, while managing land to support insect diversity, addresses both welfare bottlenecks simultaneously.