Starling murmurations are described as some of the "most amazing spectacles" to witness and they happen just before the birds go down to roost - but the reason why they do it is still uncertain.

A decade on from a study into the behaviour, researchers at University of Gloucestershire are repeating the research and inviting the public to take part in a new, nationwide study.

Lead researcher Prof Anne Goodenough said they were interested in seeing what had "changed in the past decade, particularly because starlings are a declining species".