What The Flock? Birds Perform Intricate Aerial Ballets In Winter - But We're Not Sure Why

During the winter, European starlings perform intricate aerial maneuvers called 'murmurations' at dusk -- and scientists aren't sure why.

Starling shapes in the evening sky. A large number of starlings congregate at Gretna Green every evening at sunset during the winter months to perform an elaborate aerobatic display before roosting in nearby conifer plantations. It can be quite breathtaking to witness the birds twisting into unusual patterns in the sky. (Credit: Walter Baxter / CC BY-SA 2.0)

Throughout the northern hemisphere, the dark cold months between November and February are the time when European starlings, Sturnus vulgaris, come together every evening into large flocks known as “murmurations”. Prior to settling in to their chosen communal sleeping place for the night, these birds perform a series of intricate aerial manoeuvres, where the flock repeatedly circles, and changes shape and density above their roost site for roughly half an hour at dusk.