David Tipling / Sand martin (Riparia riparia) at nest in sea cliff, North Norfolk, UK, June.

David Tipling / Sand martin (Riparia riparia) leaving nest in cliff, Salthouse, Norfolk, UK, June.

David Tipling / Sand martin (Riparia riparia) feeding young in nest hole at colony in sandstone cliffs, North Norfolk, UK, June.

David Tipling / Sand martin (Riparia riparia) leaving nest at colony in sea cliff, North Norfolk, UK, June.

Mick Jenner / Common kingfisher (Alcedo atthis) stunning and eating sand eel prey, River Looe, Cornwall, England, UK, June.

Markus Varesvuo / Sand martin (Riparia riparia) in flight over water, Uto, Finland, July.

David Pattyn / Sand martin (Riparia riparia) sitting on wires during migration. Greece. May

Juan Manuel Borrero / Illustration of Hirundinidae family: Common Sand Martin (Riparia riparia), Northen House-Martin (Delichon urbicum), Common Swift (Apus apus) and Barn Swallow (Hirundo rustica). Pencil and watercolor p...

Martin H Smith / Aerial view of Common seals {Phoca vitulina} on sand spit, Blakeney point, Norfolk, UK

Martin H Smith / Aerial view Common seals {Phoca vitulina} on sand spit, Blakeney point, Norfolk, UK

Martin H Smith / Aerial view of sand spit with Common seal colony {Phoca vitulina} Blakeney point, Norfolk

Philippe Clement / Common sand martin (Riparia riparia) in flight, silhouette against white background. Digitally enhanced silhouette.