SIMON BOOTH / SCIENCE PHOTO LIBRARY SIMON BOOTH / SCIENCE PHOTO LIBRARY
Sand martin (Riparia riparia) in flight, returning to its nest in a sandstone cliff (right). Another sand martin is peering out from one of the nesting holes. This bird is also known as the bank swallow, since it is often found nesting in waterside cliffs and banks. Photographed in the UK.
Model release not required. Property release not required.