The Atlantic salmon spends most of its life at sea, but makes an epic journey back to the river or stream in which it hatched to spawn. Look out for it in freshwater rivers in the north and west…

The yellow meadow ant is known for creating anthills in grassland habitats. It has a close relationship with the chalkhill blue butterfly - protecting the larvae in return for a sugary substance…

Freshwater pearl mussels spend their adult lives anchored to the river bed, filtering water through their gills and improving the quality of the water for other species.

The chocolate-brown, plump dipper can often be seen bobbing up and down on a stone in a fast-flowing river. It feeds on underwater insects by walking straight into, and under, the water.

The tiny, brown-and-white sand martin is a common summer visitor to the UK, nesting in colonies on rivers, lakes and flooded gravel pits. It returns to Africa in winter.

Famously predatory, the long, slender pike will lurk among the vegetation of a river or lake, bursting out with ferocious speed to catch its prey. Look out for it across the UK.

The greylag goose can be easily spotted around parks, gravel pits and river valleys, but these populations tend to be semi-tame, having been reintroduced. Truly wild populations can be found in…