One of the best preserved raised bogs in Western Europe and one of the last remaining intact midland raised bogs in Ireland

Mongan Bog is an raised active bog located 12kms south of Athlone and 1.5kms east of the Clonmacnoise National Monument. It is believed to be 9,000 years old and has formed in a basin between two east-west trending eskers. This area is recognised, nationally and internationally, for its scientific importance as one of the last remaining midland raised bogs in Ireland. Raised bogs are accumulations of deep peat (typically 3-12m) that originated in shallow lake basins or topographic depressions [Note 1]. Elevated surfaces, or domes, arise as raised bogs grow upwards due to the accumulation of peat. While at first glance Mongan Bog might seem flat and featureless, in reality the bog has a distinctly irregularly terrain typical to raised bogs.

Mongan Bog is a mostly intact, wet raised bog that has hummock and pool formations throughout a large portion of the surface of the bog. Some of the hummocks are 150cm high and hold the midlands record for raised bog hummocks [Note 2]. Its lowest strata are thought to be among the oldest in Ireland. Due to this, it remains as a tangible link to the past, as little has changed for the bog since the time of the monastic settlement. Besides the archaeology the area surrounding the bog is also rich in biodiversity supporting important habitats such as the Shannon Callows, Eskers, and limestone pavement. It is one of the only remaining intact bogs in the area, as other bogs which were intact until the 1960s when exploitation of turf led to their drainage and destruction. The preservation of this bog is increasingly important it is estimated that less than 10% of the original raised bog habitat in Ireland is in a near intact state (uncut), with less than 0.5% continuing to support actively peat forming raised bog habitat. Together with remnants of primeval forests, they form our oldest surviving ecosystems. The conservation of bogs like Mongan is important from an international perspective as Ireland has approximately 60% of the remaining habitat in Western Europe.

Mongan Bog is home to many different species of fauna and flora. In the past, Mongan Bog used to be a refuge for Greenland white-fronted geese (up to 40 individuals), however, in recent years the visits have been declining. Other birds known to breed on the site include many species whose populations are in steep decline in Ireland such as Curlew, Snipe, Skylark, and Meadow Pipit while the site is also home to the common Mallard [Note 3]. In Winter Mongan provides hunting habitat for another threatened species the Hen Harrier. Other birds of prey seen on site include White-Tailed Sea Eagle, Short Eared Owl and Buzzard.

Sphagnum mosses are the most typical and conspicuous type of vegetation in the bog area, and various species of Sphagnum can be identified throughout the bog. These mosses build the bog and contribute to the low pH balance of the soil due to its release of hydrogen ions after selectively absorbing plant nutrients [Note 4]. Other plants typical to the bog include; bog asphodel, bog cotton, deer sedge, ling heather, cross-leaved heath, and lichens. In particular, the bog is lined with both ling heather and cross-leaved heath which form low bushes in the bog. Each can be distinguished by the arrangement of their leaves.

Other plants include; bladderwort, bog bean, white-beaked sedge, and long-leaved sundew. Both the bladderwort and the sundew are perennials that are seen in the spring and summer months. They are also insectivorous plants [Note 5].

Some of the perhaps most important fauna on the bog are the insects and spiders that take residence there. These insects and spiders feed on flies and moths that have most likely been blown onto the bog from the land on the margin. Spiders compete with each other, ground beetles, and water bugs for meals, while also being the meal themselves to frogs which live on the bog.

A number of animals are found on the bog including the common frog and the Irish hare which is known to munch on the soft shoots produced in the springtime months. The hare's main source of food consists of bog cotton, deer sedge, and sometimes heather. Marginal areas of the bog support badger and red fox.

Due to past interferences, there are areas of the bog that have dried out due to various causes such as marginal drainage, fires, and domestic turf cutting. The dried areas of the bog are hazardous because they have the potential to catch fire, which can spread to intact parts of the bog. Conservationists are tasked with preventing fires as well as future drying effects when protecting the Mongan Bog [Note 6].

The importance of Mongan Bog on a national and international level is reflected in its multiple designations. In 1987 the Mongan Bog was designated a National Nature Reserve and subsequently in 1988 it was designated a RAMSAR site and recognised as a Biogenetic Reserve as part of the Council of Europe network of reserves. The area also makes up large proportion of Special Protected Area (SPA) for Birds, part of a proposed Clonmacnoise Heritage Zone, a Special Area of Conservation (SAC) and a Natural Heritage Area. Mongan Bog is one of 12 Raised Bog Habitats in Ireland, in which active habitat restoration works began in the summer of 2016, to restore and enhance the conservation status of the site. This project is part of a EU LIFE project. It has also become a part of Ireland's Ancient East along with Clara Bog.


Note 1: “Mongan Bog SAC.” Conservation Objectives Supporting Document. Natural Parks and Wildlife Services.

Note 2: “The Heritage of Clonmacnoise.” Environmental Sciences Unit, Trinity College in association with County Offalay Vocational Education Committee. Dubin, Ireland. 1987. Print.

Note 3: “Mongan Bog SAC.”

Note 4: “Sphagnum mosses – the bog builder.” Irish Peatland Conservation Council.

Note 5: “The Heritage of Clonmacnoise.”

Note 6: “Mongan Bog SAC.”

Area (in hectares): 125.61
Title Type: Freehold
Acquired from: Bord na Mona
Date acquired: 1st January 1979
An Taisce Local Association: Offaly
Open by appointment for research
Location: Mongan, Co Offaly
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