Why do starling swarm in the sky? What are they communicating, if anything? Is it play? There doesn’t seem to be a clear response on any website I have searched.

But I have discovered that it is called a ‘murmuration of starlings’, which I like. It evokes the astonishing burr of all those wings in unison, which can be heard whenever you pass close to a group. The RSPB website says:

We think that starlings do it for many reasons. Grouping together offers safety in numbers – predators such as peregrine falcons find it hard to target one bird in the middle of a hypnotising flock of thousands.

They also gather to keep warm at night and to exchange information, such as good feeding areas. 

They gather over their roosting site, and perform their wheeling stunts before they roost for the night. 

The starlings I photographed through my car windscreen (I stopped the car first) were swarming over the flatlands of Ampurdan, near the fresh and saltwater marshes of the Aiguamolls reserve. But I find it hard to be convinced that they gather in this way to keep warm at night (especially as it was mild, and mid-afternoon), and nor am I convinced by the peregrine falcon theory (there are eagles here in the Ampurdan also) and the hypnosis effect on such birds of prey.

An article in The Guardian informs readers that The Society of Biology is calling on the British public to “help them solve the mystery of why murmurations form, how long they last and why they end.”