Delay cutting or first grazing date on grasslands to create variation in sward height

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

Study locations

Key messages

  • Seven studies evaluated the effects on butterflies and moths of delaying cutting or first grazing dates on grasslands. Two studies were in Germany and one was in each of the UK, Hungary, Switzerland, Austria and Sweden.

COMMUNITY RESPONSE (4 STUDIES)

  • Community composition (1 study): One replicated, site comparison study in Austria found that the community composition of butterflies and day-flying moths was different between early-mown and late-mown grasslands.
  • Richness/diversity (3 studies): One of three replicated, controlled studies (including two randomized studies and two paired studies) in the UK, Germany and Switzerland found that, in one of four years, grassland plots cut once/year in July had a higher species richness of butterflies than plots cut once/year in May. One study found that, in one of three years, grassland strips mulched once/year in September had a lower species richness of butterflies than strips mown once/year after 10 June. The third study found that meadows mown 1–2 times/year after 15 July had a similar species richness of butterflies and burnet moths to meadows mown twice/year after 15 June.

POPULATION RESPONSE (6 STUDIES)

  • Abundance (6 studies): Three of four replicated, controlled studies (including three randomized studies and three paired studies) in the UK, Germany, Hungary and Switzerland found that grassland cut once/year in July or September had a greater abundance of butterflies, burnet moths and caterpillars than grassland cut once or twice per year in May or June, but in two of the cases only in one of four or two of three years. The fourth study found that meadows mown once/year in September had a similar abundance of scarce large blue butterflies to meadows mown once/year in May, and abundance remained stable in September-mown meadows but decreased over time in May-mown meadows. One site comparison study in Germany found that a meadow mown once/year after the flight season of tufted marbled skipper had a lower density of eggs than a meadow mown before the flight season. One replicated, site comparison study in Sweden found that meadows where grazing commenced after 15 June (together with a lower stocking density) had a higher abundance of clouded Apollo butterflies than meadows where grazing commenced before 15 June (together with a higher stocking density).

BEHAVIOUR (1 STUDY)

  • Use (1 study): One replicated, site comparison study in Austria found that short-tailed blue showed a preference for late-mown meadows, but marbled white and meadow brown preferred early-mown meadows.

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 site comparison study in 1994 in three traditional hay meadows in Bavaria, Germany (Dolek & Geyer 1997) found that the egg density of tufted marbled skipper Carcharodus flocciferus was higher in a meadow mown before the flight season than in either a meadow mown after the flight season or a grazed meadow. The egg density of tufted marbled skipper were higher in a meadow mown before the species’ flight season (4.3 eggs/20 leaves) than in a meadow mown after the flight season (0.3 eggs/20 leaves) or a grazed meadow (0.2 eggs/20 leaves). Three meadows, which had been managed in the same way for at least 5–20 years, were compared. Two traditionally managed hay meadows were mown once/year in either July or early August, and one meadow was extensively grazed with sheep, cattle or horses for a few weeks each summer. No information is provided on how eggs were recorded.

    Study and other actions tested
  2. A replicated, randomized, controlled study in 2002–2006 on four lowland farms in Devon and Somerset, UK (Potts et al. 2009) found that grassland plots cut in July had a higher abundance and species richness of butterflies, and abundance of caterpillars, than plots cut in May in only one out of four years. In the second year of management, the abundance of caterpillars on plots cut in July (6 caterpillars/transect) was higher than on plots cut in May (2 caterpillars/transect), but in other years there was no significant difference (July: 1–8; May: 0–5 caterpillars/transect). In the third year, the abundance (4 individuals/transect) and species richness (2 species/transect) of butterflies on plots cut in July was higher than on plots cut in May (abundance: 2 individuals/transect; richness: 1 species/transect), but both abundance and richness were similar in all other years (July: 1–5 individuals/transect, 1–2 species/transect; May: 1–3 individuals/transect, 1–2 species/transect). In April 2002, six experimental plots (50 × 10 m) were established on permanent pastures (>5-years-old) on four farms. Three plots/farm were cut to 10 cm height in May, and three were cut to 10 cm height in July. From June–September 2003–2006, butterflies were surveyed once/month on a 50-m transect through the centre of each plot. In April, June, July and September 2003–2006, caterpillars were counted (but not identified) on two 10-m transects/plot using a sweep net (20 sweeps/transect).

    Study and other actions tested
  3. A replicated, paired, controlled study in 2006–2008 in 10 meadows in Hessen, Germany (Handke et al. 2011) found that grassland cut in autumn had a higher abundance, but not species richness, of butterflies than grassland cut in summer. In the first and third year, the abundance of butterflies on strips where mowing was delayed (80–90 individuals/strip) was higher than on conventionally mown strips (10–50 individuals/strip), but in the first year the species richness on the delayed strips (9 species/strip) was lower than on the conventional strips (12 species/strips). There was no significant difference between strips before mowing in any year (delayed: 10–110 individuals/strip, 4–7 species/strip; conventional: 10–120 individuals/strip, 4–8 species/strip), or after the conventional strips were cut in the second year (delayed: 40 individuals/strip, 4 species/strip; conventional: 10 individuals/strip, 2 species/strip). From 2006–2008, in each of 10 meadows, two 500-m2 strips (usually 5 × 100 m) were managed in one of two ways: mulched annually in September or mown annually after 10 June. In 2007, most mowing took place in August due to wet weather. From May–August 2006–2008, butterflies were surveyed 4–6 times/year with 100 sweeps/strip of a 32-cm diameter net, and recording of other individuals at the same time (two meadows not surveyed in 2008).

    Study and other actions tested
  4. A replicated, randomized, paired, controlled study in 2007–2010 in four meadows in Őrség National Park, Hungary (Kőrösi et al. 2014) found that grassland mown in September had a similar abundance of scarce large blue butterflies Phengaris teleius to grassland mown in May, and that numbers decreased in May-mown grassland but remained stable in September-mown grassland. Three years after management began, the number of scarce large blue butterflies in plots mown in September (0.94 individuals/plot/day) was similar to the number in plots mown in May (0.86 individuals/plot/day). However, the number of butterflies in September-mown plots was similar to the first year of management (1.21 individuals/plot/day), whereas the number in May-mown plots was higher in the first year of management (1.64 individuals/plot/day). In May 2007, four meadows were each divided into two equal-size plots, and one of two management regimes was randomly applied to each plot. For four years, one plot/meadow was mown annually in May and the other was mown annually in September, all with cuttings removed. In July 2007 and 2010, butterflies were surveyed for five minutes, 15–20 times/year, in each of three or four 20 × 20 m squares/plot.

    Study and other actions tested
  5. A replicated, randomized, paired, controlled study in 2010–2013 in 23 meadows in the Swiss Plateau, Switzerland (Bruppacher et al. 2016) found that delaying the first cutting date on extensively managed meadows increased the abundance, but not species richness, of butterflies and burnet moths. Before 15 June, the abundance of butterflies and burnet moths in delayed cut meadows (1.7–2.3 individuals/100 m) was higher than in standard agri-environment scheme (AES) meadows (1.1–1.3 individuals/100 m). After 15 June, delayed cut meadows retained higher butterfly abundance (12.6 individuals/100 m) than standard meadows (2.3 individuals/100 m). After 15 July, delayed cut meadows had lower abundance (9.3 individuals/100 m) than standard meadows (17.9 individuals/100 m), but there was no difference by the end of the summer (delayed: 12.0; standard: 14.6 individuals/100 m). There was no significant difference in the species richness of delayed (10 species) and standard (8 species) meadows. In 2010, at 11 sites (>5 km apart), two meadows (0.3–1.7 ha) which had been in AES since at least 2004 were randomly allocated to two treatments: standard Swiss AES management (no cutting before 15 June) or delayed cutting (no cutting before 15 July). An additional standard meadow was included at a 12th site. On average, standard meadows were cut twice/year, while delayed cutting meadows were cut 1.5 times/year. From late April–August 2013, butterflies were surveyed along a transect (65–215 m) through the middle of each meadow. Three surveys were conducted before 15 June, one from 15 June–15 July, and two after 15 July.

    Study and other actions tested
  6. A replicated, site comparison study in 2013–2015 in 45 semi-natural grasslands in eastern Austria (Fiedler et al. 2017) found that grasslands managed by early mowing and former vineyards managed by late mowing had distinct butterfly and day-flying moth communities. Butterfly and day-flying moth communities in semi-natural grasslands managed by early mowing were different to those in grasslands (former vineyards) managed by late mowing, and both were different to communities in grasslands managed by extensive grazing (data presented as model results). In addition, some species showed a preference for sites that were early-mown (marbled white Melanargia galathea, meadow brown Maniola jurtina), late-mown (short-tailed blue Cupido argiades) or grazed (crepuscular burnet Zygaena carniolica, transparent burnet Zygaena purpuralis/minos). The use of all three grassland management regimes (early mowing, late mowing and grazing) in different parts of the landscape increased butterfly diversity across the landscape (data presented as model results). Semi-natural grasslands managed in three ways were studied: meadows mown once/year in early summer with cuttings removed, former vineyards mown once/year in late summer with cuttings not removed, and extensive pastures grazed by cattle from April–October. In June 2013–2015, all butterflies, burnet moths (Zygaenidae) and hummingbird hawk-moths Macroglossum stellatarum were counted once on 9–11 sites/year (50 × 50 m) under each management type.

    Study and other actions tested
  7. A replicated, site comparison study in 1984–2015 in 24 grasslands in Blekinge province, Sweden (Johansson et al. 2017) found that grasslands grazed lightly, later in the year or with fewer animals, had a higher abundance of clouded Apollo Parnassius mnemosyne than grasslands grazed heavily, earlier in the summer or with more animals. In grasslands managed by light grazing, the abundance of clouded Apollo (1–169 individuals/grassland/year) was higher than in heavily grazed grasslands (2–22 individuals/grassland/year) or ungrazed grasslands (0–109 individuals/grassland/year). In addition, abundance was higher on larger grasslands, and grasslands which were close together were more likely to be colonized (data presented as model results). From 1984–2015, twenty-four open grasslands (>150 m apart) with >0.5 m2 cover of the host plant Corydalis spp. and the presence of a major nectar plant Lychnis viscaria were assigned annually to one of three management categories: light grazing (grazing commenced after 15 June with 1–9 animals/hectare); heavy grazing (grazing commenced before 15 June or with ≥10 animals/hectare for ≥8 weeks); no grazing. Grazing animals were cattle and sheep. In 1984–1987, 1991 and 2003–2015, butterflies were surveyed ≥6 times/year on each site, by marking and recapturing individuals along irregular routes through each grassland. In 1988–1989 and 1992–2002, grasslands were visited more irregularly and their presence recorded. Surveys were used to estimate the local population size on each grassland each year.

    Study and other actions tested
Please cite as:

Bladon A.J., Smith R.K. & Sutherland W.J. (2022) Butterfly and Moth Conservation: Global Evidence for the Effects of Interventions for butterflies and moths. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

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