Ireland’s geographic isolation as an island nation, formed by rising sea levels after the last Ice Age, has shaped its distinctive animal populations. This isolation has resulted in fewer terrestrial mammal species compared to mainland Europe. Despite this, the Emerald Isle supports a variety of wildlife, adapted to its diverse landscapes, from coastal areas to mountainous regions. Its natural environment provides habitats for many species.
Mammals of Ireland
Ireland is home to a range of terrestrial and marine mammals. Only 26 land mammal species are considered native to the island, excluding marine mammals and bats. Some species, such as the red fox, European hedgehog, stoat, otter, and badger, are widely distributed across the country.
Among the iconic native land mammals is the Irish Hare, a subspecies unique to Ireland. Unlike other mountain hares, it typically does not turn white in winter, maintaining a russet-brown coat. The Red Deer, Ireland’s largest land mammal, has been present since the last Ice Age, with the Killarney National Park herd being the only native wild population. Pine Martens, once rare, are now recolonizing areas across Ireland following legal protection in 1976. These agile predators are known for their rich brown fur and a distinctive creamy-yellow bib.
Introduced terrestrial mammals have also become naturalized. Common examples include the European rabbit, grey squirrel, bank vole, and brown rat. Other common rodents are the wood mouse, house mouse, and yellow-necked field mouse, with brown rats widespread near human settlements.
Irish waters are frequented by a variety of marine mammals, including numerous cetacean species and seals. Two species of seals are resident: the Common (or Harbour) Seal and the Grey Seal. Common Seals are generally smaller with a rounded head, while Grey Seals have a more angular profile. Both species establish haul-out sites along the Irish coastline. Additionally, 24 species of cetaceans and five species of sea turtles have been recorded in Irish waters, including Minke and Fin Whales.
Birds of the Irish Skies
Ireland’s diverse landscapes, from its coastal cliffs to its expansive wetlands, provide habitats for many bird species. Over 450 unique bird species visit Ireland annually, though most are migratory. Common resident birds, such as the Robin, Blackbird, and Wren, are familiar sights across the island.
Birds of prey like the Kestrel and Buzzard soar above Irish fields and woodlands. These raptors play an important role in regulating prey populations within their ecosystems.
Coastal cliffs and wetlands are particularly important for various bird species. Puffins, with their distinctive colorful beaks, can be found nesting on these rugged coastal formations. Various species of geese and waders also utilize Ireland’s wetlands as wintering grounds or stopover points during their migratory journeys.
Reptiles, Amphibians, and Freshwater Fish
Ireland’s reptile and amphibian populations are notable for their limited diversity, influenced by the island’s post-glacial isolation. Uniquely, Ireland is known for the absence of native snakes, a common misconception often attributed to folklore. The Common Lizard (Zootoca vivipara) is the sole native terrestrial reptile found across the island. This lizard is viviparous, giving birth to live young, an adaptation that allows it to thrive in cooler climates.
The Smooth Newt (Lissotriton vulgaris) is Ireland’s only native tailed amphibian and one of just three amphibian species on the island, alongside the common frog and the Natterjack toad. Smooth newts are typically found in still or slow-moving water bodies during their breeding season, though they are terrestrial for much of the year. They can be distinguished from lizards by their smooth, moist skin and the presence of four toes on their front feet.
Ireland’s freshwater systems support several fish species, including the Atlantic Salmon, Brown Trout, and Pike. Brown Trout are the most widespread freshwater fish, found in nearly every stream, river, and lake. Varieties of brown trout have evolved in certain lakes, such as Lough Melvin. Pike, a large predatory freshwater fish, are also common in many Irish lakes and rivers.
Marine Invertebrates and Other Ocean Dwellers
Beyond its charismatic marine mammals, Ireland’s coastal waters and deeper seas teem with a rich variety of invertebrate life and diverse fish species. The country’s marine habitats are ecologically important, supporting complex food webs. These include a range of invertebrates such as crabs, lobsters, jellyfish, sea anemones, and starfish.
Crabs and lobsters inhabit the seabed, often found in rocky crevices and sandy areas along the coast. Jellyfish, including various species, drift through the water column, while sea anemones and starfish cling to rocks or move slowly across the seafloor. These invertebrates play various roles, from filter feeders to scavengers.
Ireland’s marine fish populations are extensive, encompassing commercially important species and larger pelagic fish. Cod, haddock, and mackerel are common marine fish found in these waters, supporting significant fisheries. The large Basking Shark, a filter-feeding cartilaginous fish, is also a notable visitor to Irish coastal waters, particularly during warmer months. The deep-sea areas off Ireland’s continental margin also harbor unique deep-sea fish species.