For botanists, there are 500 species of local flora recorded, including some rarities such as sea samphire, marsh helleborine and most rare of all an orchid, Spiranthes romanzoffiana. There are bluebells in spring, and wild garlic, primroses and yellow irises; brilliant blue scillas in the coastal rocks and harebells in the sand dunes; and, of course, everywhere in the summer the subtle variety of heather colours.
From choughs to golden eagles, the birdwatcher has over 150 birds to look out for. The very rare corncrake breeds on Colonsay and it's cicada like rasp is familiar sound in the fields from May onwards. The guillemots breed in their thousands on the cliffs at Pigs Paradise and it is possibele to see fulmar colonies, red-throated divers and the amazing acrobatics of gannets at sea.
There are colonies of grey seals and they can be spotted all around the coast of the island. Otters are found along the eastern coast of the island and occasionally dolphins, porpoises and basking sharks can be seen further out to sea.