Why do starling 'murmurations' happen?
10 November 2014 Last updated at 06:54 GMT
It's a spectacular sight - thousands of starling birds flying together to create mesmerising patterns called 'murmurations'.
It's thought it could be a form of protection from predators, or a way of signposting a roost.
Martin went starling watching in Brighton and spoke to bird expert Dr Anne Goodenough from the University of Gloucestershire to find out more.