Restore or create grassland/savannas

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 grassland or savanna. Three studies were in the USA, two were in the UK, and one was in Italy.


  • Richness/diversity (1 study): One replicated, paired, site comparison study in Italy found that created semi-natural grasslands had a greater diversity of butterflies than adjacent conifer forests, but a lower diversity than species-rich pastures.


  • Abundance (4 studies): Two site comparison studies (including one replicated, paired study) in Italy and the USA found that created semi-natural grasslands and restored grasslands and oak barrens had a higher abundance of butterflies and regal fritillaries than adjacent conifer forests, species-rich pastures or unmanaged or remnant prairies. One site comparison study in the USA found that prairies restored 5–10 years ago by seeding with native species, mowing, and weeding or applying herbicide, had a greater abundance of Fender’s blue eggs than a prairie restored 1–2 years ago, and a similar abundance to remnant prairies. One study in the USA reported that restored prairie supported a translocated population of regal fritillaries for at least three years after restoration.


  • Use (2 studies): One of two replicated, before-and-after studies in the UK reported that following grassland restoration the area occupied by small pearl-bordered fritilliaries increased. The other study reported that following grassland restoration the number of marsh fritillary populations at each site remained the same or increased.
  • Behaviour change (1 study): One site comparison study in the USA found that Fender’s blue butterflies spent a similar proportion of time laying eggs in prairies restored 5–10 years ago by seeding with nectar species, mowing, and weeding or applying herbicide, and in remnant prairies.

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 study in 1998–2004 on former cropland in Iowa, USA (Shepherd & Debinski 2005) reported that restored prairie supported a translocated regal fritillary Speyeria idalia population. In 2001, the first year after translocation to a restored prairie, no butterflies were seen, but in 2002, one year after a second release, 84 adults were recorded. In the following two years, 11–12 fritillaries were observed in planted violet plots and other areas on 1–2 days/year. On 15 days in 2004, between 1–23 fritillaries were seen/day. Within a 2,083-ha reserve, 1,250 ha of former cropland were restored to tallgrass prairie (no further detail provided). The remaining land contained scattered remnant prairie patches. In 1998 and 1999, prairie violets Viola pedatifida were planted in five plots at each of four sites across the reserve. Each plot contained 99 violets planted in a grid (9 × 11 m), 1 m apart. In July 2000 and August–September 2001, seven female fritillaries were caught and brought to the restored prairie. Fritillaries were placed in mesh cages (0.6 × 0.6 m or 1.8 × 1.8 m) directly over violet plants, and provided with nectar from cut flowers and moved to new violet plants each day. In June–August 2001–2004, butterflies were surveyed or opportunistically recorded across the site.

    Study and other actions tested
  2. A replicated, before-and-after study in 2002–2009 in six grassland sites in County Durham, UK (Ellis and Wainwright 2012) reported that following scrub and bracken control, mowing, planting of marsh violet Viola palustris and common dog-violet Viola riviniana, grazing management and shelterbelt planting, the area occupied by small pearl-bordered fritillary Boloria selene increased. Results were not tested for statistical significance. In 2000, two years before management, small pearl-bordered fritillary were recorded as occupying 1.10 ha at 4 of 4 surveyed sites. Seven years after management started they were recorded across 5.99 ha over 6 of 6 surveyed sites, although 2.95 ha of this across three sites were not surveyed in 2000. Of the four sites that were surveyed in their entirety in 2000, the area occupied by small pearl-bordered fritillary increased in three of them. From 2002, scrub and bracken were controlled and grass was mowed at all sites (frequency not given). Grazing compartments of an average of 1.2 ha were installed at five sites but they remained ungrazed or lightly grazed by sheep until after 2009. At two sites, either 0.06 ha or 0.09 ha of violets were planted. Six areas of shelterbelt were planted at one site. Butterfly transects were conducted annually in 2000–2009, except at one site where weekly transects were conducted from 2004 (annual surveying months not given). The total area surveyed in each year is not given.

    Study and other actions tested
  3. A replicated, before-and-after study in 2005–2010 in seven pastures in Devon, UK (Plackett et al 2012) reported that in areas with scrub and bracken Pteridium aquilinum control, along with some planting of devil’s bit scabious Succisa pratensis, tree felling and livestock grazing, the number of marsh fritillary Euphydryas aurinia populations at each site either remained the same or increased. Results were not tested for statistical significance. Five pastures had one population of marsh fritillary in 2005 and were managed with scrub and bracken control (and a mixture of devil’s bit scabious planting, tree felling and livestock grazing), after which three still had one population and two had two populations in 2010. Another two similarly managed sites did not have a population in 2005 but did in 2010. In 2005–2010, western gorse Ulex galli, willow Salix spp., soft rush Juncus effusus, greater tussocksedge Carex paniculata and bracken were managed in seven pastures. In the same period, trees were felled in two of the pastures, devil’s bit scabious was planted in one pasture and all pastures had some livestock grazing. In 2005 and 2010, surveyors conducted timed adult marsh fritillary counts during their flight season and caterpillar web counts in the autumn.

    Study and other actions tested
  4. A site comparison study in 2009–2010 in three restored fields in Oregon, USA (Carleton & Schultz 2013) found that older restored prairie had a higher density of Fender’s blue butterfly Plebejus icarioides fenderi eggs than recently restored prairie. Five to 10 years after restoration, the host plant Kincaid’s lupine Lupinus oreganus had more butterfly eggs (0.04–0.16 eggs/leaf) than 1–2 years after restoration (0.002–0.004 eggs/leaf), but similar numbers to intact habitat (0.09–0.13 eggs/leaf). Lupine density was also higher 5–10 years after restoration (5.1–9.0 leaves/m2) than 1–2 years after restoration (0.3–1.3 leaves/m2), but lower than in intact prairie (54.5 leaves/m2). The time spent laying eggs by females was similar in older restored habitat (3–10%) and intact habitat (11%). From 2000, 2004 and 2008, three former fields (0.1–0.6 ha) were restored by seeding with native Fender’s blue nectar species and Kincaid’s lupine for 1–4 years. Restoration sites were adjacent to 3.5 ha of intact prairie. Restored areas were mown, and either hand weeded or treated with herbicide to reduce the spread of non-native plants. At the end of the 2009 and 2010 flight seasons, the number of lupine leaves and the number of Fender’s blue eggs were sampled in the restored and intact prairie. In May–June 2009, female butterflies were observed in restored (38 females) and intact (116 females) prairie, and the percentage of time spent laying eggs was recorded.

    Study and other actions tested
  5. A replicated, paired, site comparison study in 2010 three alpine grassland and forest sites in the Aosta Valley, Italy (Rolando et al. 2013) found that created semi-natural grasslands had a higher abundance and diversity of butterflies than adjacent conifer forest, and a higher abundance but lower diversity of butterflies than nearby species-rich pastures. On created grasslands, the total number of butterflies recorded (1,133 individuals) was higher than on pastures (759 individuals) or in forests (1,060 individuals). However, species diversity on created grasslands was lower than on pastures but higher than in forests (data presented as model results). Created semi-natural grassland strips (>15-years-old) were occasionally grazed by cattle in summer, and used as ski-pistes in winter. Species-rich pastures were grazed annually by cattle. From 20 July–20 August 2010, butterflies were surveyed on twenty 300-m transects in each of three habitats: created grassland, adjacent coniferous forest, and nearby pastures.

    Study and other actions tested
  6. A site comparison study in 2014 in a restored grassland and oak barren landscape in Indiana, USA (Shuey et al. 2016) reported that regal fritillary Speyeria idalia were found across a landscape restored by planting and rotational burning. Results were not tested for statistical significance. Eighteen years after restoration began, on four restoration sites with high plant diversity, the abundance of regal fritillaries peaked at 17 butterflies/30-minute transect, compared to 12 butterflies/transect on two remnant prairies and a low plant diversity restoration site, 19 butterflies/transect in an old field, and 0 butterflies/transect in an agricultural field. Prior to restoration, authors reported that regal fritillaries were only found at three small sites in the landscape. Beginning in 1996, over 3,240 ha of agricultural land was restored to native grassland and oak barrens by planting seed mixes containing nearly all known locally native species (>620 species). In addition, seeds (<1 ounce/year) and plugs (<1,000 plants/year) of arrowleaf violet Viola sagittata and bird’s-foot violet Viola pedata were planted as host plants. The area was managed to control invasive species and, once established, patches were burned on a three-year rotation. From May–September 2014, butterflies were surveyed every two weeks on 30-minute transects at nine sites across the landscape: four restoration sites with high plant diversity, one restoration site with low plant diversity, two remnant prairies, one old field, and one site still in agricultural production, none of which had been burned during the previous year.

    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?

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Butterfly and Moth Conservation

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Butterfly and Moth Conservation
Butterfly and Moth Conservation

Butterfly and Moth Conservation - Published 2023

Butterfly and Moth Synopsis

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