Restore or create peatland

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Six studies evaluated the effects on butterflies and moths of restoring or creating peatland. Two studies were in each of Finland and the UK, and one was in each of the Netherlands and Ireland.


  • Community composition (1 study): One replicated, paired, site comparison study in Finland found that mires restored by filling ditches and cutting trees had a moth community which was intermediate between drained and pristine mires.
  • Richness/diversity (2 studies): One replicated, paired, controlled, before-and-after study in Finland found that after mires were restored by raising the water table and removing large trees, they had a higher species richness of mire specialist butterflies than before restoration or than unrestored, drained mires, and a similar species richness to pristine mires. One replicated, paired, site comparison study in Ireland reported that protected bogs re-wetted by blocking drains had a similar species richness of moths to unrestored and unprotected bogs.


  • Abundance (4 studies): Two before-and-after studies (including one replicated, paired, controlled study) in the UK and Finland found that bogs re-wetted by blocking drains and mires restored by raising the water table and removing large trees had a higher abundance of rosy marsh moth caterpillars and mire specialist butterflies than before restoration or than unrestored mires, and a similar abundance to pristine mires. Two replicated, paired, site comparison studies in Finland and Ireland found that mires restored by filling ditches and cutting trees and bogs restored by blocking drains (along with legal protection) had mixed effects on moth abundance compared to unrestored sites depending on species.
  • Survival (1 study): One replicated study in the UK found that where water levels had risen due to peatland restoration, large heath butterfly caterpillars had lower winter survival than in areas where water levels had not risen.


  • Use (1 study): One replicated, site comparison study in the Netherlands found that wet heathland where water levels had been recently raised were less frequently occupied by Alcon large blue than sites where the water level had not been raised.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated study in 1996–1998 in two peatland sites in Wrexham and Shropshire, UK (Joy and Pullin 2001) found that where water levels had risen due to peatland restoration, large heath butterfly Coenonympha tullia caterpillars had lower winter survival than in areas where water levels had not risen. Caterpillars on cotton-sedge tussocks Eriophorum vaginatum in plots with high water levels resulting from restoration activities had lower winter survival (0–35%) than caterpillars on tussocks where the restoration had not affected water levels (54–63%). Prior to the study (years not given) drains were blocked at Fenn’s and Whixall Mosses to raise water levels as part of a site restoration programme to create wetter areas of the sites. In winter 1996–1997 one dry study plot was located at Whixall and one wet plot at Fenn’s, but in 1997–1998 both the wet and dry plots were located at Whixall. In September 1996 and 1997, twenty captive-reared large heath caterpillars were put on each of four low-lying cotton-sedge tussocks in that year’s plots (two plots/year and a total of 80 caterpillars/ plot).

    Study and other actions tested
  2. A before-and-after study in 1988–2003 in a raised bog in Ceredigion, UK (Fowles et al. 2004) reported that a re-wetted bog supported a larger population of rosy marsh moth Coenophila subrosea caterpillars than before drains were blocked. Results were not tested for statistical significance. One to five years after the last drains were blocked, 27–88 caterpillars/year were recorded, compared to 8–27 caterpillars/year in the preceding 10 years. From the mid-1980s, large drains surrounding a raised bog were dammed. In 1993 and 1998, shallow peat-cuttings were also blocked, raising the water table at the site from 42 cm to 48 cm over 15 years. In late May 1988–2003, caterpillars were counted once/year, at night, in fourteen 15 × 1 m plots along a transect across the bog.

    Study and other actions tested
  3. A replicated, site comparison study in 1998–1999 on 68 wet heathland sites in the Netherlands (WallisDeVries 2004) found that raising water levels reduced occupancy by Alcon large blue Maculinea alcon. Fewer recently flooded sites were occupied by Alcon large blue (48%) than non-flooded sites (85% occupancy), and sites where measures had been taken to raise the water level were more likely to be flooded (68%) than sites without such measures (35%). Sixty-eight wet heathland sites in the Netherlands where Alcon large blue was known to have occurred since 1990 were selected. Management information for the last five years was obtained by sending questionnaires to land managers. Changes in management designed to raise water levels had been used at 31% of sites (further details not provided). From mid-July–early September 1998–1999, Alcon large blue eggs were counted in each of three 10 × 10 m plots/site to determine butterfly presence in the plot.

    Study and other actions tested
  4. A replicated, paired, site comparison study in 2007 in nine boreal mires in Central Finland and Northern Karelia, Finland (Noreika et al. 2015, same experimental set-up as 5) found that mires restored by ditch-filling and tree cutting had moth communities which were intermediate between those found on drained and pristine mires. One–three years after restoration, the moth community on restored mires was intermediate between the communities found on drained and pristine mires (data presented as model results). One of three mire specialist micro-moths (rush marble Bactra lancealana) and one of two specialist macro-moths (Manchester treble-bar Carsia sororiata) were more numerous in restored than drained sites, but were most abundant in pristine sites. However, one specialist micro-moth (Crambus alienellus) and one specialist macro-moth (Arichanna melanaria) were more abundant in the drained sites than restored sites. A third specialist micro-moth (pearl-band grass-veneer Catoptria margaritella) did not differ in abundance between restored, drained and pristine sites (see paper for details). In the 1960s and 1970s, parts of nine mires were drained for forestry. From 2003–2006, some drained areas were restored by filling ditches with peat, damming the ends with logs and peat, and cutting trees. Each mire also contained a pristine, undrained area. In 2007, moths were sampled along two 250-m transects in each restored, drained and pristine area (six transects/mire). From May–August, micro-moths were sampled weekly using 100 sweeps/transect of a 28-cm diameter net at all nine mires. From May–July, macro-moths were counted weekly along each transect at five of the mires.

    Study and other actions tested
  5. A replicated, paired, site comparison study in 2011 in 12 bogs in County Offaly, Ireland (Flynn et al. 2016) found that protected bogs, some of which had been re-wetted, had a similar total abundance and species richness of moths to unprotected bogs, but individual species showed mixed preferences. The total number of moths recorded on protected bogs was 951 individuals of 67 species, compared to 865 individuals of 73 species on unprotected bogs (statistical significance not assessed). Of the 14 most common species, three were more abundant on protected bogs (dark arches Apamea monoglypha, large yellow underwing Noctua pronuba, dark tussock Dicallomera fascelina), three were more abundant on unprotected bogs (map-winged swift Pharmacis fusconebulosa, narrow-winged pug Eupithecia nanata, spruce carpet Thera britannica), and eight showed no difference (data presented as model results). Of 15 bog-associated species of conservation concern, only three (dark tussock, bordered grey Selidosema brunnearia, garden tiger Arctia caja) were recorded in higher numbers on protected sites than on unprotected sites (statistical significance not assessed). Six raised bogs (74–246 ha) designated as Special Areas of Conservation, and six nearby (1.5–5 km away), highly modified but vegetated undesignated raised bogs (40–578 ha) were selected. At four of the protected sites, restoration work (mostly drain blocking) had taken place. From July–October 2011, moths were sampled five times using a Heath-type actinic 15 W light trap left overnight at each site. Paired sites were sampled on the same night, and all sites were sampled over two nights/visit.

    Study and other actions tested
  6. A replicated, paired, controlled, before-and-after study in 2003–2014 in 19 boreal mires in Finland (Noreika et al. 2016, same experimental set-up as 3) found that restoring mires by raising the water table and removing large trees increased the abundance and species richness of mire specialist butterflies. On restored mires, the abundance (1.8 individuals) and species richness of mire specialist butterflies was higher than on drained mires (0.8 individuals), and similar to pristine mires (2.9 individuals; data for species richness not presented). Prior to restoration, abundance and species richness were similar in sites to be restored (1.4 individuals) and drained sites (1.7 individuals), but higher on pristine sites (3.6 individuals). See paper for individual species results. Each of 19 mires comprised three habitats: drained sites which were restored during the study, drained sites that remained in forestry use throughout the study, and undrained pristine sites. At restored sites, tall trees were removed and the water table was raised. Nine mires were restored between 2004 and 2006, and 10 were restored from 2011–2013. Six 250-m transects were established in each mire (2 transects/habitat, 80 m apart). Beginning in May, butterflies were surveyed weekly in years before (2003 or 2010) and after (2007 or 2014) restoration at each mire (7–15 visits/site/year), and divided into specialists (species which predominantly occur on mires) and generalists (species which predominantly occur in other habitats).

    Study and other actions tested
Please cite as:

Bladon A.J., Bladon, E. K., Smith R.K. & Sutherland W.J. (2023) Butterfly and Moth Conservation: Global Evidence for the Effects of Interventions for butterflies and moths. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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Butterfly and Moth Conservation

This Action forms part of the Action Synopsis:

Butterfly and Moth Conservation
Butterfly and Moth Conservation

Butterfly and Moth Conservation - Published 2023

Butterfly and Moth Synopsis

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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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