The tightly packed, thistle-like purple flower heads of common knapweed bloom on all kinds of grasslands. Also regularly called black knapweed, this plant attracts clouds of butterflies.

Heather is also called 'ling'. Look for it on our heaths, moors and bogs, where its delicate, loosely arranged pink flowers attract all kinds of nectar-loving insects.

The muntjac deer was introduced into the UK from China in the 20th century. It has gained a stronghold in southeast England, where it can cause damage to our woods through browsing.

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.

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 UK hosts a small, but important, breeding population of ruff. The ruff is a large sandpiper that is so-called due to the large ruff of feathers around the males' neck. This is used in a…