... Impenetrable as the flock’s movements might seem to the human eye, the underlying maths is comparatively straightforward. Each bird strives to fly as close to its neighbours as possible, instantly copying any changes in speed or direction. As a result, tiny deviations by one bird are magnified and distorted by those surrounding it, creating rippling, swirling patterns. In other words, this is a classic case of mathematical chaos (larger shapes composed of infinitely varied smaller patterns). Whatever the science, however, it is difficult for the observer to think of it as anything other than some vast living entity.
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The logic behind this spectacular behaviour is simple: survival. Starlings are tasty morsels for peregrines, merlins and sparrowhawks. The answer is to seek safety in numbers, gathering in flocks and with every bird trying to avoid the edge where adept predators can sometimes snatch a victim. ...