Although introduced by humans, the fallow deer has been here so long that it is considered naturalised. Look out for groups of white-spotted deer in woodland glades.

The grey squirrel was introduced into the UK in the 1800s. It provides an easy encounter with wildlife for many people, but can be damaging to woodlands and has contributed to the decline of the…

The Norway spruce was introduced into the UK from Scandinavia in the 16th century. It is familiar to us all as the 'original' Christmas tree and displays hanging, reddish-brown, oblong…

Pineappleweed is an introduced species that has become a widespread 'weed' of disturbed ground, such as pavements and roadsides and gardens. It has feathery leaves and yellow flower…

The White-clawed crayfish is a freshwater, bronze-coloured crustacean with pale undersides to its claws - hence the name. It is under threat from an invasive and introduced species of crayfish.…

Buddleia is a familiar shrub, well-known for its attractiveness to butterflies. It is actually an introduced species, however, that has become naturalised on waste ground, railway cuttings and in…

With a silvery body, and purple, pink and bluish streaks down its flanks, the rainbow trout lives up to its name. Popular with anglers, it is actually an introduced species in the UK.

A tall, domed tree of woodlands, hedgerows and parks, the introduced sycamore is familiar to many of us the 'helicopter' producing tree - its large, winged fruits appearing in autumn.…

Cotoneaster was introduced to the UK in 1879 from Eastern Asia as an ornamental plant. It is now an invasive non-native species which is taking over valuable habitats including limestone…

Lilac is an introduced species in the UK that can sometimes be found in hedgerows and along woodland edges. Flower spikes appear in spring, beautifully scented and packed with small, lilac-pink…