Barnacles are so common on our rocky shores that you've probably never really noticed them. They're the little grey bumps covering the rocks that hurt your feet when you're…

This small duck is an uncommon winter visitor to the UK, where they're usually found on lakes, reservoirs and gravel pits.

The greater horseshoe bat was once a cave-dweller, but now tends to roost in old buildings, such as churches and barns. It is rare in the UK and, like many other bats, declining in number.

The lesser horseshoe bat was once a cave-dweller, but now tends to roost in old buildings, such as stables and barns. It is rare in the UK and, like many other bats, declining in number.

Red-necked grebes occasionally attempt to nest in the UK, but they're more often seen as winter visitors to sheltered coasts.

Swifts spend most of their lives flying – even sleeping, eating and drinking – only ever landing to nest. They like to nest in older buildings in small holes in roof spaces.

The tiny, grey-brown house mouse is one of our most successful mammals. It thrives around buildings but is less likely to be found in our houses these days due to better construction.

The serotine is one of the first bats to appear at night and can be seen around lamp posts chasing moths, or at treetop height. It likes to roost and hibernate in old buildings in the south of the…

Look out for the bright red eyes of this speedy crab in rockpools - but be careful, they're notoriously feisty and will give a painful nip!

This small summer migrant travels from Africa to breed in the reedbeds of the UK. Rarely seen but given away by its insect like trilling call; the movement of the head during calling makes it…