Native oysters are a staple of our seas and our plates - but our love of their taste has lead to a sharp decline all around the UK.

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

The slippery butterfish is a common sight in rockpools all around the UK. Look out for the distinctive black spots on their backs that look a lot like eyes!

The Glanville fritillary can be spotted on warm days around coastal habitats on the Isle of Wight and the Channel Islands, as well as at a few locations in mainland England.

The Purple hairstreak is an elusive butterfly with a brilliant purple sheen. It is entirely reliant on oak trees and can be spotted chasing around the treetops in woodlands and parks.

The all-black carrion crow does not nest in colonies like the similar rook. It can be seen almost everywhere.

This small finch nests on moorlands and coastal crofts, spending the winter on the coast. The UK population has declined dramatically.

A tall and robust species of sedge, the Great fen-sedge has long leaves with sawtooth edges. It forms dense stands in lowland fens and around lakes.

The greenshank breeds on the boggy moors and ancient peatlands of Scotland. But it can be spotted elsewhere in the UK as it passes through on migration - look around lakes, marshes and the coast…