Why do starlings fly long distances to join murmurations?

Large roosts offer ‘neighbourhood watch’ security. Picture: iStock

Bands of starlings are roaming the countryside; the winter flocking season has arrived. Reinforcements from mainland Europe will join them, assembling into huge ‘murmurations’ at dusk. There will soon be hundreds of thousands of birds at traditional locations.

Why starlings fly tens of kilometres to join a multitude of their peers has not been fully explained. Protection from cold during winter nights is probably a factor. All those warm bodies, huddled together on branches, raise the temperature of a roosting site. But travelling long distances to avail of this seems slightly daft. Surely more energy is used flying to and from the site than will be gained overnight. Wouldn’t joining smaller, more local, aggregations be just as effective? And cross-country flying is risky; predators may be lying in wait around the murmuration site.