During the winter months, starlings (especially in the U.K.) will form into massive flocks of 100,000 or more and put on a hypnotizing show in the sky. It’s called a 'Murmuration.’

But why do they do this? They initially roost together at night for warmth, but predators will find it quite difficult to target one bird in a flock of thousands.

The starling population has fallen by more than 80% in recent years, meaning they are now on the critical list of UK birds most at risk.

In Iowa, the European Starling was first seen in 1922 and within a decade the birds could be found in all 99 counties.

Nature photographer Marco Valk recorded these starling murmurations in the Netherlands:

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