Introduction
What is the main tool used by the state to protect the Marsh Fritillary butterfly?
Under the EU Habitats Directive 1992, certain geological features, habitats and species must be protected within Special Areas of Conservation (SACs). One of the species is the Marsh Fritillary butterfly. Ireland had to identify areas important for the Marsh Fritillary butterfly and designate them as Special Areas of Conservation. This was also required of European Union countries with populations of the butterfly. Where an area is designated for the butterfly, the butterfly is named as a ‘qualifying interest’ for the Special Area of Conservation. A full list of Ireland’s SACs can be found here:
https://www.npws.ie/sites/default/files/files/SAC%20quick%20reference%20table(1).pdf
Ireland listed 12 SACs with the Marsh Fritillary as a qualifying interest (other qualifying interests are listed too). The 12 sites are listed here:
https://www.npws.ie/protected-sites/search/by-feature?feature%5B%5D=6133&designation%5B%5D=375
A check of the documents available for each site at https://www.npws.ie/protected-sites is interesting reading. The documents consist of
1. Conservation Objectives: these aim to define favourable conservation conditions for particular habitats or species at that site. The Conservation Objectives state whether the Marsh Fritillary is present and the area of suitable habitat within the SAC.
2. Site Synopsis: this states the site location, and summarises the habitats, species, and importance of the site and comments on any threats to the site’s conservation values.
3. Statutory Instrument (SI) and SAC maps: The SI designates the SAC, states the qualifying interest species and habitats, and sets out the activities that require ministerial consent. The maps identify the area occupied by the SAC.
What do the Conservation Objective Reports tell us about the butterfly’s status on the sites?
The Marsh Fritillary was recorded in just four of the 12 SACs where the butterfly is named as a ‘qualifying interest’. These are:
1. Bricklieve Mountains and Keishcorran SAC
2. East Burren Complex SAC
3. Moneen Mountain SAC
4. West of Ardara/Maas Road SAC
The association of the species with the SAC derives from a paper by Lavery (1993) which refers to a site called Foynes/Barrigone as one of three major populations in Ireland. A 2012 survey did not find the species in the SAC (Wilson et al., 2013).
Was Lavery correct when he wrote the paper? Did NPWS undertake a survey to confirm the species before the site was designated? Why is the Marsh Fritillary listed as a qualifying interest if it is absent?
The area occupied by the Marsh Fritillary at Barrigone has dried out and is now overgrown with scrub. Geoffrey Hunt, a reliable recorder, has searched the area regularly since 1998 and has not seen any Marsh Fritillary on the site. Geoffrey’s knowledge of the site raises questions concerning this statement from the site’s Conservation Objectives report:
In 2012, just over 9ha of habitat was assessed as suitable for the species (NPWS, 2019).
Is there any suitable habitat at Barrigone?
The Conservation Objective reports for the following four sites where the Marsh Fritillary is a qualifying interest for the SAC do not even mention the butterfly:
1. Bunduff Lough and Machair/Trawalua/Mullaghmore
2. Gweedore Bay and Islands SAC
3. Sheephaven SAC
4. St. John’s Point SAC.
I visited Bunduff Lough and Machair/Trawalua/Mullaghmore SAC (terrestrial area 1,812.12ha) and St. John’s Point SAC (terrestrial area 152.08ha) and found larval webs within these sites. However, while I did not measure the area of suitable habitat on these sites, the areas are not extensive.
I calculated the combined area of the SACs (excluding maritime areas for coastal sites) and, where provided, the area of suitable habitat for the butterfly. In two Burren SACs, NPWS estimated suitable habitat. Combined, the 12 SACs contain 159,647.26 hectares. The total suitable habitat stated is 5,725.2 hectares.
The ratio of suitable habitat in hectares to overall terrestrial area in these SACs is 1:28. There is one hectare of suitable habitat for the Marsh Fritillary for every 28 hectares of land.
The Marsh Fritillary occupies the landscape in a metapopulation structure. It needs a network of sites within a region for long-term survival. In England, the minimum figure is 50ha (50ha2 is ½ km2) of suitable habitat within an area of 16km2 (1600ha) Bulman et al., 2007. (This ratio is 1ha: 32ha.). Modelling suggests the species may persist in areas below this area for decades, but extinction will eventually result unless additional habitat is provided. Irish research is needed concerning this aspect (NPWS, 2019).
If the ecology of the Marsh Fritillary reflects that in England, the combined habitat area across the 12 SACs designated to protect the species slightly exceeds the minimum threshold needed for long-term survival.
However, taken on a regional basis, only the two Burren SACs, which are extensive (but much smaller than the Connemara and Killarney SACs), contain habitat that significantly exceeds the minimum required. The Burren SACs and the habitat and habitat ratios are:
East Burren Complex (18800.65 ha (188 km2)): 3,200 ha (32 km2): ratio 1:6 and Moneen Mountain (6100ha (61 km2): 2,500ha (25 km2): ratio 1:2.4.
A thorough calculation of the ratio in regions holding the smaller SACs would need to factor in any suitable habitat adjoining the SAC to assess the species on a regional basis. It must be stressed that the exercise undertaken here is unrefined. The SACs in question are, in most cases, separated by significant distances and cannot be said to reflect the metapopulation structure of the species, so extrapolating the ratio of suitable habitat to the area in the SACs as a whole inadequately represents the ratio situation described by Bulman et al. (2007), which could be much lower in some areas.
The absence of detailed management plans for some SACs is another problem. How do we know if the habitat is being managed correctly? In this regard, it must be emphasised that the Burren’s populations are safe, for now.
This cannot be said of many populations elsewhere. Look at Barrigone, once regarded as one of the three major populations in Ireland. Look at Killarney and Ballynafagh, where it is either very rare or no longer occurs. These are sites where protecting the Marsh Fritillary is a conservation priority.
Protecting the butterfly means protecting its habitat, which preserves many important habitats and species. The absence of the butterfly highlights poor habitat quality, bad practice and lack of care. In the view of this author, the summative assessment is ‘poor result is due to the lack of serious effort.’
The formative assessment is to apply the required habitat management techniques to restore and maintain habitat within SACs and expand the network of protected areas and manage these areas to meet the minimum habitat size of 50ha within 16km2 to ensure this lovely butterfly’s long-term survival.
Reserves Protecting the Marsh Fritillary
Two areas set aside for nature, where the land is specifically managed for the Marsh Fritillary, are Butterfly Conservation Ireland’s Crabtree Reserve in Lullybeg, and the Irish Peatland Conservation Council’s Lullymore West Butterfly Reserve, both in County Kildare. Both sites hold long-term, thriving populations. Both sites are managed for the butterfly. In August 2026, surveys found over 80 larval webs in these sites.
How is the Marsh Fritillary doing in Ireland?
An Atlas of Butterflies in Ireland 2010-2021, published in 2025, provides interesting information about the distribution of the Marsh Fritillary in Ireland.
The Atlas shows the species distribution in three periods: 1900-2010, 1995-2010 and 2010-2021. The number of occupied 10km squares in each of the periods is:
1900-2010: 435 (42.7%)
1995-2010: 248 (24.3%)
2010-2021: 355 (34.7%)
There are significant differences for the three time spans, but the figures for the two most recent periods are more relevant.
A key issue arising with the 2010-2021 recording period is that in 100 of the 353 10km squares, only a single Marsh Fritillary was recorded. The Marsh Fritillary is a colonial species. A single butterfly is not evidence of a colony. If these 100 squares are discounted, this leaves its distribution at 24.8% of Ireland’s 10km squares. This would mean its distribution has remained almost unchanged since the 1995-2010 recording period.
Nevertheless, the distribution change reported in the Atlas in the 2010-2021 period is +43%, indicating a positive trend. This positive finding is supported by the findings of the most recent report by the state to the EU Commission, ‘The Status of EU Protected Habitats and Species in Ireland 2025′, which assessed the Overall Status of Marsh Fritillary as
Favourable, which represents a genuine improvement since the Inadequate assessment reported in 2019. The change is because of an improvement in the future prospects for range, population and habitat for the species. Threats and pressures do exist but are not considered to be severe or extensive. The overall trend is improving. (NPWS, 2025, Vol. 1, p.52 )
However, this report states that 90% of Ireland’s EU priority habitats are in unfavourable condition, including several habitats used by the species: Molinia meadows, orchid-rich calcareous grassland, alkaline fens, wet heaths, dry heaths, alpine and sub-alpine heaths, machair, dune slacks.
For example, the assessment for orchid-rich calcareous grassland concludes:
Despite a number of conservation-focused farming schemes which bring about localised and regional improvements, the Overall Status is assessed as Bad with a deteriorating trend due to on-going habitat losses mainly associated with unsuitable grazing regimes, agricultural intensification causing loss of species-rich communities, and abandonment of farmland resulting in succession to scrub. This result is unchanged from 2019 (NPWS, 2025, Vol. 1, p. 29 ).
The assessment of Molinia meadows concludes:
The Overall Status is Bad, as it has been for the last three monitoring periods, and the overall trend is still deteriorating, due to on-going losses of habitat. Significant historical losses of this habitat have also occurred since the EU Habitats Directive came into force. The main pressures on the habitat are associated with agricultural intensification (e.g. land drainage, fertiliser application), undergrazing and forestry (NPWS, 2025, Vol. 1, p. 30).
The loss drivers identified are common to many other habitats used by the species. A new threat, renewable energy infrastructure, threatens colonies in cutover bogs.
The Marsh Fritillary also occurs in habitats that do not correspond to the habitat types described in the manuals used to identify EU-protected habitats. These factors threaten its habitats. In addition, many midland populations are in cutover bogs where cutting has ceased. These are becoming overgrown with scrub and woodland, shading the habitats and removing the butterfly; the Marsh Fritillary is shade intolerant.
Conclusion
The continuing decline in the status of EU priority habitats in Ireland threatens many species, including Ireland’s only legally protected insect, the Marsh Fritillary. Unless the loss of habitat is stopped, the butterfly, which is rarely found more than 15km from a known colony and which has disappeared from many areas in northern Europe, will lose its ability to move around in the landscape, key to its capacity to repopulate sites where it has gone extinct due to the impacts of parasitism, unsuitable weather and deterioration of habitat.
Ireland has a low number of butterfly species. Can’t we protect the few we do have?
All photographs copyright J.Harding
References
Bulman, C.R., Wilson, R.J., Holt, A., Galvez Bravo, L., Early, R., Warren, M.& Thomas, C.D. (2007) Minimum viable metapopulation size, extinction debt, and the conservation of a declining species. Ecological Applications 17: 1460–1473.
Harding, J. & Lysaght, L. (Eds.) (2025) An Atlas of Butterflies in Ireland 2010-2021. The National Biodiversity Data Centre, Waterford.
NPWS (2019). The Status of EU Protected Habitats and Species in Ireland. Volume 3: Species Assessments. Unpublished NPWS report. Edited by: Deirdre Lynn and Fionnuala O’Neill
NPWS (2025). The Status of EU Protected Habitats and Species in Ireland. Volume 1: Summary Overview. Unpublished NPWS report.
Edited by: Domhnall Finch, Aoife Delaney, Fionnuala
O’Neill and Deirdre Lynn
NPWS (2021) Conservation Objectives: Ballynafagh Lake SAC 001387. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.
NPWS (2019) Conservation Objectives: Barrigone SAC 000432. Version 1. National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht.
NPWS (2021) Conservation Objectives: Bricklieve Mountains and Keishcorran SAC 001656. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.
NPWS (2015) Conservation Objectives: Bunduff Lough and Machair/Trawalua/Mullaghmore SAC 000625. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.
NPWS (2015) Conservation Objectives: Connemara Bog Complex SAC 002034. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.
NPWS (2022) Conservation Objectives: East Burren Complex SAC 001926. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.
NPWS (2015) Conservation Objectives: Gweedore Bay and Islands SAC 001141. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.
NPWS (2021) Conservation Objectives: Moneen Mountain SAC 000054. Version 1. National Parks and Wildlife Service, Department of Housing, Local Government and Heritage.
NPWS (2017) Conservation Objectives: Killarney National Park, Macgillycuddy’s Reeks and Caragh River Catchment SAC 000365. Version 1. National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht.
NPWS (2014) Conservation Objectives: Sheephaven SAC 001190. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.
NPWS (2015) Conservation Objectives: St. John’s Point SAC 000191. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.
NPWS (2015) Conservation Objectives: West of Ardara/Maas Road SAC 000197. Version 1. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht.