Mandatory Credit: Photo by Paul Marriott/Shutterstock (12439403ay) Thousands of birds including knot gather on a sand bank at Snettisham, Norfolk. This spectacular happens when a high tide forces the birds from their feeding ground on The Wash, further up the beach and onto the shingle, before the tide recedes and they can feed on the mudflats again. Birds, Snettisham, Norfolk, UK, September 9, 2021. Birds, Snettisham, Norfolk, UK, September 9, 2021., Snettisham, Snettisham, England - 09 Sep 2021