Ireland is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the second-largest island of the British Isles, the third-largest in Europe, and the twentieth-largest on Earth.
Unlike Great Britain which had a land bridge with mainland Europe, Ireland only had an ice bridge ending around 14,000 years ago at the end of the last ice age and as a result it has fewer land animal and plant species than Great Britain or mainland Europe. There are 55 mammal species in Ireland, and of them only 26 land mammal species are considered native to Ireland. Some species, such as, the red fox, hedgehog and badger, are very common, whereas others, like the Irish hare, red deer and pine marten are less so. Aquatic wildlife, such as species of sea turtle, shark, seal, whale, and dolphin, are common off the coast. About 400 species of birds have been recorded in Ireland. Many of these are migratory, including the barn swallow.
Several different habitat types are found in Ireland, including farmland, open woodland, temperate broadleaf and mixed forests, conifer plantations, peat bogs and a variety of coastal habitats. However, agriculture drives current land use patterns in Ireland, limiting natural habitat preserves, particularly for larger wild mammals with greater territorial needs. With no large apex predators in Ireland other than humans and dogs, such populations of animals as semi-wild deer that cannot be controlled by smaller predators, such as the fox, are controlled by annual culling.
There are no snakes in Ireland, and only one species of reptile is native to the island. Extinct species include the Irish elk, the great auk, brown bear and the wolf. Some previously extinct birds, such as the golden eagle, have been reintroduced after decades of extirpation.
Ireland is now one of the least forested countries in Europe. Until the end of the Middle Ages, Ireland was heavily forested. Native species include deciduous trees such as oak, ash, hazel, birch, alder, willow, aspen, rowan and hawthorn, as well as evergreen trees such Scots pine, yew, holly and strawberry trees. Only about 10% of Ireland today is woodland; most of this is non-native conifer plantations, and only 2% is native woodland. The average woodland cover of European countries is over 33%. In the Republic, about 389,356 hectares is owned by the state, mainly by the forestry service Coillte. Remnants of native forest can be found scattered around the island, in particular in the Killarney National Park.
Much of the land is now covered with pasture and there are many species of wild-flower. Gorse, a wild furze, is commonly found growing in the uplands and ferns are plentiful in the more moist regions, especially in the western parts. It is home to hundreds of plant species, some of them unique to the island, and has been 'invaded' by some grasses, such as Spartina anglica.
The algal and seaweed flora is that of the cold-temperate variety. The total number of species is 574 The island has been invaded by some algae, some of which are now well established.
Because of its mild climate, many species, including sub-tropical species such as palm trees, are grown in Ireland. Phytogeographically, Ireland belongs to the Atlantic European province of the Circumboreal Region within the Boreal Kingdom. The island can be subdivided into two ecoregions: the Celtic broadleaf forests and North Atlantic moist mixed forests.