Listen out for the 'chattering' song of the reed warbler, while wandering the UK's lowland wetlands in summer. A small, brown bird, they are quite hard to see.

The Common walnut tree produces a large, brown nut that is familiar to so many of us. It is an introduced species in the UK, and can be seen in towns, gardens and parks.

Tawny owls are the familiar brown owls of Britain’s woodlands, parks and gardens. They are known for their ‘too-wit too-woo’ song that can be heard at night-time.

A diminutive but aggressive predator, the three-spined stickleback hunts tadpoles and small fish. It is also known for fiercely protecting its nest of eggs until they hatch. Look for it in ponds,…

The stiff, spiky and upright leaves and brown flowers of hard rush are a familiar sight of wetlands, riversides, dune slacks and marshes across England and Wales.

The small heath is the smallest of our brown butterflies and has a fluttering flight. It favours heathlands, as its name suggests, as well as other sunny habitats.

Brush through a wildflower meadow at the height of summer and you'll hear the tiny seeds of yellow-rattle rattling in their brown pods, hence its name.

The rare Adonis blue can be spotted on sunny chalk grasslands throughout summer. Males are a dazzling sky-blue in colour, while females are duller brown.

The eel is famous for both its slippery nature and its mammoth migration from its freshwater home to the Sargasso Sea where it breeds. It has suffered dramatic declines and is a protected species…