The Natural World

Photo by Mark Chaddock

Achill Island can boast a flora as varied as its topography, from common species such as birdsfoot trefoil (Lotus corniculatus), found at sea level, to rare arctic alpine species such as Juniper (Juniperus communis), found on the peaks of Slievemore and Croaghaun.

Bog / Peatlands

Achill is characterised by its large expanses of blanket bog / peatlands. Peatlands are recognised as one of the unique features of Achill’s heritage. Bog or peat is largely made up of water with its solid matter consisting of partly decayed plant remains. Blanket peatlands have formed over thousands of years, only occurring in areas where there is a high annual rainfall, i.e. in excess of 125mm. The peatlands of Achill which sweep from the mountains to the sea sustain unique communities of plant and animals. Plants such as purple moor grass (Milinia caerulea), ling heather (Calluna vulgrais) and sphagnum moss (Sphagnum) dominate the surface of the bog. Bog cotton (Eripphorum angustifolium), bog asphodel (Narthecium ossifragum), cross-leaved heath (Erical tetralix) and bell heather (Erica cineria) provide pockets of colour with black bog rush (Schoenus nigricans) and white beak-sedge (Rhynchospora alba) are also typical. Insectivourous plants such as sundew (Drosera rotundifolia), butterwort (Pinguicula vulgrais) and bladderwort (Utricularia spp.) adapt to the nutrient-poor environment by trapping and digesting insects to gain extra nutrients. Bog myrtle (Myrica gale) is a low growing shrub with a distinctive aroma, commonly found at the lower altitudes. Irish heath (Erical hivernica) is a rare heather only occurring in north-west Mayo, Spain and Portugal. It can be seen blooming on the Curran Peninsula and at the back of Croughan in early spring. Other rare plants found in Achill include St. Patrick’s cabbage (Saxifraga spathularis), dwarf willow (Salix herbacea), bearberry (Arctostaphylos uva-ursi) and a species of eyebright (Oxyria digna) specific to Croughan.


Machair is the name given to coastal grassland on a sandy substrate and stems from the Irish, Machaire, which means a plain stretch of level ground. Machair is only found in north-west Ireland and north-west Scotland and is a priority habitat afforded special protection from the European Union. Machair started to develop just after the last Ice Age due to a number of factors such as the high wind velocities and grazing. In Achill, machair is found in a number of sites, the best examples being found in Keel, Dugort and Valley. Early to mid-June find the machairs a blaze of colour, with flowers such as wild thyme (Thymus praecox), daisy (Bellis perennis), birds foot trefoil (Lotus corniculatus) and lady’s strawbed (Carex), mosses (Sphagnum) and liverwort are also well represented in this habitat. One of the important species found in this habitat is petalwort, a rare liverwort that is listed on Annex II and Annex IV of the European Habitat Directive.


Many animals such as the Irish hare (Lepus timidus hibernicus) and fox (Vulpes vulpes) are widespread throughout Achill. The otter (Lutra lutra), Irish stoat (Mustela erminea hibernica), badger (Meles meles), pygmy shrew (Sorex minutus) and bats are commonly observed. Ireland’s only lizard – Irish common lizard (lacerta viviparta) – is also present on Achill, feeding on insects found on local bogs and sand dunes. They are about 5 inches long with tail, sandy grey or brown. They often sun themselves on dry-stone walls. (View images of Irish lizard.). One of the important animals to the local ecosystem is the common frog (Rana temporaria), which occurs on most of the habitats found in Achill. A particularly beautiful specimen is the elephant hawk moth, which breeds on Achill and which has fascinating caterpillars. We are indebted to Achill resident Mark Chaddock for the photographs below (and above, of the lizard).


Achill, once the home of the mighty Golden eagle (Aquila chrysaetos), which became extinct in the area in 1912, can still boast a wealth of birdlife, from common birds like the meadow pipit (Anthus pratensis) and syklark (Alauda arvensis), which are commonly found singing on local boglands, to rare protected species like the chough (Pyrrhocorax pyrrhocorax) found breeding in the Croughan area. Other rare birds sighted locally are the golden plover (Pluvialis apricaria), dunlin (Calidris alpina), merlin (Falco columbarius and peregrine falcon (Falco peregrinus), with other migrants such as the barnacle goose (Branta leucopsis) passing through. Birds such as common snipe (Gallinago gallinago), curlew (Numenius arquata), lapwing (Vanellus vanellus) and resident oystercatcher (Haematopous ostralegus) are often to be found on the local machair. One of the most recognisable local birds is the grey heron (Ardea cinerea) found on the local bogs, rivers and lakes. Achill resident Mark Chaddock has documented no fewer than 83 bird species on Achill, as well as observing other interesting mammals / amphibians. 

Geology & Glaciation

The basement rocks of Achill and the Curraun Peninsula are the oldest in Ireland. They date to the Pre-Cambrian period and were formed over 600 million ago. These rocks consist primarily of schist, gneiss and quartzite. In general the rugged mountain peaks consist of quartize, and schist is dominant in the lowland valleys. Layers of peat overlay drift deposits. The two highest mountain peaks, namely Slievemore (672m) and Croughan (668m) stood out as nunataks during the last glaciation of Ireland, i.e the Midlandian, which came to an end 10,000 years ago. Lough Acorrymore is a fine example of a corrie or cirque with an impressive hanging valley lying directly above it. Lough Nakeeroge East, which lies approximately 16m above sea level, is the lowest corrie lake in Ireland. Another corrie lake, Lough Bunafreeva West, is perched on the edge of a steep cliff on the western side of Croaghaun Mountain, 350m above sea level. It is thought that submergence or a rise in sea level is responsible for the separation of Inishbiggle from Achill Island and the creation of a narrow channel 300m wide. Cloughmore, Achill Beg and the south-western portion of the Corraun Peninsula were also joined together at one time and were subsequently separted whwn the Atlantic cut its way through the unresisting rock, thus forming The Sound.