A stunning display of thousands of starlings performing a murmuration has been captured on Anglesey.
The video was taken by Sarah Williams-Davies as the birds swooped and dived in unison over Tyddyn Pwrpas Caravan Site.
What is it?
According to the RSPB, it is basically a mass aerial stunt - thousands of birds flying in unison and is completely breathtaking to watch.
The RSPB says it thinks starlings do it for many reasons including for safety - predators such as peregrine falcons find it hard to target one bird in the middle of a hypnotising flock of thousands.
It says starlings also gather to keep warm at night and to exchange information, such as good feeding areas.
They gather over their roosting site, and perform their wheeling stunts before they roost for the night.
Despite them often appearing in huge numbers, the starling population has fallen by more than 80% in recent years, according to the RSPB, meaning they are now on the critical list of UK birds most at risk.
The decline is believed to be due to the loss of permanent pasture, increased use of farm chemicals and a shortage of food and nesting sites.