This stunning footage was captured by Colin Hogg, a Geophysics Fieldwork Technician at the Geophysics Section of Dublin Institute for Advanced Studies, over Lough Ennell in Co. Westmeath in the Republic of Ireland.
A few years ago, George F. Young and his colleagues investigated starlings' "remarkable ability to maintain cohesion as a group in highly uncertain environments and with limited, noisy information" — a nice description of what goes on in a murmuration.
Going in, Young et al. already knew that starlings pay attention to a fixed number of their neighbors in the flock, regardless of flock density — seven, to be exact. Their new contribution was to figure out that "when uncertainty in sensing is present, interacting with six or seven neighbors optimizes the balance between group cohesiveness and individual effort."
Young et al. analyzed still shots from videos of starlings in flight (flock size ranging from 440 to 2,600), then used a highly mathematical approach and systems theory to reach their conclusion. Focusing on the birds' ability to manage uncertainty while also maintaining consensus, they discovered that birds accomplish this (with the least effort) when each bird attends to seven neighbors.