Manage hedgerows to benefit wildlife (e.g. no spray, gap-filling and laying)

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

Study locations

Key messages

COMMUNITY RESPONSE (8 STUDIES)

  • Richness/diversity (8 studies): Three replicated, site comparison studies in the UK and Costa Rica found that hedgerows with trees or a more complex structure had a higher species richness or diversity of butterflies and macro-moths than simpler hedgerows without trees. Three of five replicated studies (including three randomized, paired, controlled studies and two site comparison studies) in the UK and Italy found that hedgerows managed according to agri-environment scheme prescriptions (including less frequent or winter cutting, gap-filling and restricted mowing, in one case in combination with other agri-environment scheme habitat) had a similar species richness of butterflies and moths to conventionally managed hedgerows. The other two studies found that hedgerows cut to allow incremental growth had a higher diversity of caterpillars and pupae than hedgerows cut to the same size, and that hedgerows kept between 1–2 m tall had a higher species richness of butterflies than hedgerows kept below 1 m tall.

POPULATION RESPONSE (15 STUDIES)

  • Abundance (15 studies): Four of six replicated studies (including four randomized, paired, controlled studies, one controlled study, and one paired, site comparison study) in the UK found that hedgerows cut once every 2–3 years, cut in autumn, or cut to allow incremental growth, had a higher abundance of adult butterflies and moths, moth caterpillars and pupae and brown hairstreak eggs than hedgerows cut to the same size every winter. However, one of these studies also found that hedgerows cut to allow incremental growth had a similar abundance of moth caterpillars and pupae to hedgerows cut to the same size. The other two studies found that hedgerows managed by gap-filling and cutting every three years had a similar abundance of moths to conventionally managed hedgerows, and that hedgerows cut in winter, or less frequently in autumn, had more concealed moth caterpillars, but a similar abundance of free-living caterpillars, to hedgerows cut annually in autumn. Three of five replicated, site comparison studies (including one paired study) in the UK and Costa Rica found that hedgerows with trees had a similar total abundance of macro-moths to hedgerows without trees. The other two studies found that hedgerows with trees, or with a more complex structure, had a higher abundance of butterflies and pale shining brown moths than simple hedgerows. Two replicated, site comparison studies in Belgium and Italy found that hedgerows managed with scalloped edges, or maintained at below 1 m tall, had more brown hairstreak eggs and a higher abundance of adult butterflies, than hedgerows with straight edges or allowed to grow over 2 m tall. One of two studies (including one controlled and one replicated, site comparison study) in the UK found that laid or coppiced hedgerows had a higher abundance of butterflies than unmanaged hedgerows. The other study found that managed hedgerows had a lower abundance of caterpillars than remnant hedgerows.

BEHAVIOUR (0 STUDIES)

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, site comparison study in 1979 on a farm in Hampshire, UK (Sotherton et al. 1981) found that regularly cut and uncut hedges had a lower abundance of caterpillars than patchy, remnant hedges. In regularly cut hedges, the abundance of caterpillars (7 individuals/hedge) was similar to uncut hedges (4 individuals/hedge), and both were lower than in remnant hedges (18 individuals/hedge). Three hedges (primarily containing hawthorn Crataegus monogyna, dog rose Rosa canina and blackthorn Prunus spinosa) in each of three management categories were selected. Cut hedges (2.0–2.1 m wide, 1.7–2.2 m high) were regularly managed, and last cut around eight months before sampling. Uncut hedges (2.6–2.9 m wide, 8.0–9.0 m high) had not been cut for >5 years, but remained stock-proof. Remnant hedges (2.5–3.0 m wide, 6.0–7.5 m high) consisted of individual trees and bushes along a field edge. In July 1979, caterpillars were sampled in three locations on each side of each hedge using a beating tray.

    Study and other actions tested
  2. A controlled study in 1995–1996 along a hedgerow in Cambridgeshire, UK (Dover et al. 1997) found that laid or coppiced sections of hedge had a higher abundance of butterflies than uncut sections of hedge. There were more butterflies along laid (53–67 butterflies/plot) or coppiced (60–69 butterflies/plot) sections of hedge than along uncut sections (23–26 butterflies/plot). Meadow brown Maniola jurtina (laid: 29–48; coppiced: 28–31; uncut: 18–22 butterflies/plot), gatekeeper Pyronia tithonus (laid: 7–12; coppiced: 12–16; uncut: 1 butterflies/plot) and small heath Coenonympha pamphilus (laid: 4–5; coppiced: 7–14; uncut: 2 butterflies/plot) were all more abundant on laid or coppiced sections than on uncut sections, but small skipper Thymelicus sylvestris abundance was not significantly different between treatments (laid: 1–7; coppiced: 2–6; uncut: 0–1 butterflies/plot). A hedge was planted in the early 1960s. In winter 1990/91 the hedge was divided into twelve 20-m long experimental plots. One of three treatments was applied to each plot: laying, coppicing to ground level, or left uncut. In winter 1995/96, the laid and coppiced sections were trimmed. In summer 1995 and 1996, butterflies were surveyed on both sides of the hedge on 18–19 visits/year.

    Study and other actions tested
  3. A replicated, controlled study on seven arable and pastoral farms in England and Wales, UK (Maudsley, Marshall & West 2000) found that hedgerows cut in February had a lower abundance of butterflies and moths than hedgerows cut in September. Cutting in February rather than September reduced numbers of butterflies and moths (February: 33/plot; September: 65/plot). In 1996–1997, hedgerows on seven farms were assigned to replicated treatments (15–21 plots/farm) of different cutting times (cut in September or February) and cutting frequency (annual, biennial and triennial cutting, and uncut; results not presented). Data were obtained on the abundance of butterflies and moths in May and July within each hedgerow plot (methods and years not given).

    Study and other actions tested
  4. A replicated, paired, site comparison study in 2007 in four arable fields in Oxfordshire, UK (Merckx et al. 2009a, same experimental set-up as Merckx et al. 2009b, 2010, 2012) found no difference in the abundance of common farmland larger moth species in margins adjacent to hedgerows with or without mature trees. Field margins with trees in the adjacent hedgerow had similar numbers of nine common moth species to margins with no trees in the adjacent hedgerow (data presented as model results). On the 32 nights (dusk till dawn) with suitable weather between 5 June and 14 July 2007, eight Heath pattern actinic light traps (6 W) were positioned in two arable fields/night, one in each field margin (1 m from the hedgerow). Four traps were within 5 m of a mature (>15 m high) hedgerow tree, and four were next to hedgerows with no trees. All traps were >100 m apart and >50 m from hedgerow intersections. Traps were alternated between two pairs of fields each night, one with 6-m-wide perennial grass margins and the other with standard 1-m-wide margins. Moths were identified on the morning after capture.

    Study and other actions tested
  5. A replicated, site comparison study in 2006 in four arable areas in Oxfordshire, UK (Merckx et al. 2009b, same experimental set-up as Merckx et al. 2009a, 2010, 2012) found that farms with mature trees in their hedgerows had a higher diversity of larger moths than farms without mature trees in their hedgerows, but that the abundance of moths was similar. Farms with mature trees in their hedgerows had a higher species diversity of moths than farms without hedgerow trees (data presented as model results). However, the abundance of moths was similar between hedgerows with (25–27 individuals) and without (22 individuals) trees. Three permanent sampling sites were established >100 m apart and >50 m from hedgerow intersections at each of 16 farms. Farms were divided between four experimental groups: sampling in a 6-m-wide perennial grass margin adjacent to a mature (>15 m high) hedgerow tree, sampling in a standard 1-m margin adjacent to a hedgerow tree, sampling in a 6-m margin not adjacent to a hedgerow tree, and sampling in a 1-m margin not adjacent to a hedgerow tree. All farms were sampled once during each of 11 discrete fortnightly periods from mid-May to mid-October 2006 using standardized moth traps.

    Study and other actions tested
  6. A replicated, site comparison study in 2001–2005 in 63 hedgerows and woodland edges in an agricultural landscape in Flanders, Belgium (Merckx & Berwaerts 2010) found that hedgerows with scalloped edges contained more brown hairstreak Thecla betulae eggs than hedgerows with straight borders. There were twice as many brown hairstreak eggs on blackthorn Prunus spinosa bushes in scalloped hedgerows than in straight hedgerows (data presented as model results). In addition, more eggs were present on hedgerows lower than 1.5 m than on taller hedgerows (data presented as model results). Hedgerows and woodland edges (1–250 m long, 2,260 m total) containing blackthorn were divided into 10-m sections (338 hedgerow sections), and categorized as “scalloped”, “oval”, “boxed” or “with gaps” (exact descriptions not provided). Each winter from 2001–2005, all blackthorn bushes were systematically searched for brown hairstreak eggs.

    Study and other actions tested
  7. A replicated, site comparison study in 2006–2008 on four arable farms in Oxfordshire, UK (Merckx et al. 2010, same experimental set-up as Merckx et al. 2009a, 2009b, 2012) found that field margins next to hedgerow trees had more pale shining brown moths Polia bombycina than margins without hedgerow trees. The number of individuals caught in margins next to hedgerow trees (1.0–1.3 individuals/trap) was higher than the number in margins without trees (0.3–0.4 individuals/trap). Four farms were assigned to one of four treatments, based on their most common boundary features: 6-m-wide perennial grass or 1–2-m-wide standard field margins, and with or without hedgerow trees (>15 m high, mostly pedunculated oak Quercus robur). From May–October 2006–2008, moths were sampled overnight, once/fortnight, using three 6 W Heath pattern actinic light traps/farm. In June–July 2007 and 2008, at one farm, an additional 8–10 traps were set for 32–33 nights/year, in margins with the same treatments across 4–5 fields (16–20 locations). All traps were 1 m from hedgerows (2–3 m high, 1.5–2.5 m wide), 5 m from trees (if applicable), >50 m from hedgerow intersections, and >100 m apart.

    Study and other actions tested
  8. A replicated, site comparison study in 2005–2006 in 10 hedgerows in cattle pastures in Central Pacific Region, Costa Rica (Tobar & Ibrahim 2010) found that structurally complex hedges had a higher abundance and species richness of butterflies than simple hedges. In structurally complex hedges, butterfly abundance (321 individuals/hedge) and species richness (37 species/hedge) was higher than in simple hedges (abundance: 235 individuals/hedge; richness: 28 species/hedge). In addition, 24 species were only recorded in complex hedges, including some forest-dependent species, while five species were only recorded in simple hedges, and 46 species were recorded in both hedge types (statistical significance not assessed). Ten hedges (>200 m long) in cattle pastures were studied. Five hedges were structurally complex, with up to 29 tree species (primarily copperwood Bursera simaruba, salmwood Cordia alliodora, and pink poui Tabebuia rosea) of different heights and widths (>6 m wide), and five hedges were simpler (<6 m high and <4 m wide) with smaller and pruned trees (primarily copperwood and pochote Bombacopsis quinata, up to 13 species). In 2005, and February–May 2006, butterflies were surveyed for 45 minutes on a 120-m transect along each hedge, four times in the dry season and four times in the rainy season.

    Study and other actions tested
  9. A replicated, paired, site comparison study in 2008 on 26 farms in central Scotland, UK (Fuentes-Montemayor et al. 2011) found that hedgerows managed under agri-environment schemes (AES) had a similar abundance and species richness of moths to conventionally-managed hedgerows. In AES hedgerows, the abundance (64 individuals) and species richness (25 species) of micro-moths, the abundance (219 individuals) and species richness (33 species) of all macro-moths, and the abundance (26 individuals) and species richness (6 species) of declining macro-moths were all similar to conventionally-managed hedgerows (micro-moths: 81 individuals, 25 species; all macro-moths: 203 individuals, 32 species; declining macro-moths: 31 individuals, 7 species). In 2004, thirteen farms enrolled in AES, and were paired with 13 similar but conventionally-managed farms, <8 km away. Hedgerows on AES farms had gaps filled, and were managed with restrictions on pesticide use, no mowing of the hedge bottom, and were only cut once every three years with further restrictions on timing. Hedgerows on conventional farms had no management restrictions. From June–September 2008, moths were collected for four hours, on one night/farm, using a 6 W heath light trap located next to one hedgerow on each farm. Paired farms were surveyed on the same night.

    Study and other actions tested
  10. A replicated, randomized, paired, controlled study in 2005–2011 on an arable farm in Buckinghamshire, UK (Heard et al 2011) found that land managed under an agri-environment scheme, including hedgerow management, had a higher abundance, but not species richness, of butterflies and micro-moths than conventional farming, but there was no difference in abundance or species richness of other moths. Butterfly abundance was higher under enhanced Entry-Level Stewardship (ELS) (5,400 individuals/60 ha) and standard ELS (2,000 individuals/60 ha) than under conventional farming (1,400 individuals/60 ha). Micro-moth abundance was also higher under enhanced ELS (79 individuals) than standard ELS (32 individuals) or conventional farming (20 individuals). However, the abundance of macro-moths and threatened moths was similar under enhanced ELS (macro: 126; threatened: 6 individuals), standard ELS (macro: 79; threatened: 5 individuals) and conventional farming (macro: 79; threatened: 6 individuals). Species richness of all groups was similar under enhanced ELS (macro: 20; micro: 11; threatened: 3 species), standard ELS (macro: 20; micro: 8; threatened: 2 species) and conventional farming (macro: 18; micro: 5; threatened: 2 species) (butterfly data not presented). In 2005, a 1,000-ha farm was divided into five 180-ha blocks. Three 60-ha areas/block were assigned to three treatments: enhanced ELS (5% land removed from production, hedges cut every two years); standard ELS (1% land removed from production, hedges cut every two years); conventional (hedges cut annually) (see paper for other details). From May–August 2006–2011, butterflies were recorded four times/year on one 50-m transect/60-ha area, passing through all available habitats. In late-May 2007–2011 and late-July 2006–2011 moths were surveyed using Robinson light traps. One block was surveyed/night, with one trap/treatment.

    Study and other actions tested
  11. A replicated, site comparison study in 2006–2009 on 16 arable farms in Oxfordshire, UK (Merckx et al. 2012, same experimental set-up as Merckx et al. 2009a, 2009b, 2010) found that field margins next to hedgerow trees had a higher species richness, but not abundance, of macro-moths than margins away from hedgerow trees. The species richness of macro-moths in margins next to hedgerow trees (105 species) was higher than in margins next to hedgerows without trees (92 species), but abundance was similar (data not presented). Sixteen farms were categorized to one of four treatments, based on their most common agri-environment scheme habitat: extended 6-m-wide or standard 1-m-wide field margins, and with or without hedgerow trees (>15 m high, mostly pedunculated oak Quercus robur). All margins were well-established perennial grass strips, cut once every 2–3 years, ungrazed and unfertilized. From May–October 2006–2009, moths were sampled 40 times (once/fortnight), using three 6 W Heath pattern actinic light traps/farm. Traps were 1 m from hedgerows (2–3 m high, 1.5–2.5 m wide), 5 m from trees (if applicable), >50 m from hedgerow intersections, >100 m apart, and operated from dawn to dusk. Three farms (nine traps) were sampled/night.

    Study and other actions tested
  12. A replicated, randomized, paired, controlled study in 2005–2011 in a field in Cambridgeshire, UK (Facey et al. 2014) found that hedges cut in winter, or less frequently in autumn, had more concealed moth caterpillars than hedges cut annually in autumn, but cutting did not affect the number of free-living caterpillars or total species richness. The abundance of concealed caterpillars on hedges cut in winter (8.5–9.9 individuals/plot), or every three years in autumn (10.5 individuals/plot) was higher than on hedges cut annually in autumn (7.5 individuals/plot). The abundance of free-living caterpillars did not vary with the timing or frequency of cutting (data not presented). The total number of moth species on hedges cut in winter (3.8 species/plot) was similar to hedges cut in autumn (3.0 species/plot), and was similar between different cutting frequencies (data not presented). In 2005, three hedgerows were divided into 32 contiguous, 15-m-long plots, and randomly assigned to two treatments: cut every one, two or three years, and cut in September or January/February. Annually cut treatments were replicated eight times, and other treatments were replicated four times. From May–July 2011, caterpillars were sampled monthly in two ways. All caterpillars and mined leaves within a 1 × 0.5 m square (placed 1.5 m high, 5- and 10-m along each plot) were collected for three minutes. A 2-m section of guttering was placed through the hedge (0.8 m high, two locations/plot), and the vegetation above struck three times with a pole. Caterpillars were reared in the lab for identification, and empty leaf mines and cases were identified. Species were classified as “free-living” caterpillars which feed on the outside of leaves, and “concealed” species which mine leaves or form protective cases from them.

    Study and other actions tested
  13. A replicated, randomized, paired, controlled study in 2010–2013 on five farms in Oxfordshire, Buckinghamshire and Devon, UK (Staley et al. 2016, same experimental set-up as Staley et al. 2018) found that hedges which were cut in autumn, or once every three years, had a higher abundance of moth caterpillars and pupae than hedges cut in winter or every year, and hedges cut to allow incremental growth had a greater species diversity but similar abundance of moth caterpillars and pupae to hedges cut to a standard size. Over three years, the total abundance of caterpillars and pupae on hedges cut in winter (8–12 individuals/plot) was higher than on hedges cut in autumn (6–10 individuals/plot), and the abundance on hedges cut once every three years was higher than on hedges cut annually (data used in analysis not presented). The diversity of species on hedges cut to allow incremental growth was greater than on hedges cut to a standard size (data presented as statistical result), but abundance was similar (incremental: 7–12 individuals/plot; standard: 6–10 individuals/plot). See paper for further details. In January–February 2010, three 260-m-long hedges on each of five farms were cut. From September 2010, each hedge was divided into twelve 20-m sections, to which each combination of three sets of management options were applied for three years: cut once every one, two or three years; cut in September or January/February; and cut to the same dimensions or with the cutting bar raised by 10 cm on each successive cut to allow incremental growth. In May 2011–2013, caterpillars and pupae were sampled by inserting guttering (2 m × 11.2 cm) through each hedge, 80 cm above ground, at 5, 10 and 15 m along each plot, and beating the vegetation. Caterpillars and pupae were reared until emerging adults could be identified.

    Study and other actions tested
  14. A replicated, site comparison study in 2014–2015 in 44 sites in a mixed farming region in Lombardy, Italy (Luppi et al. 2018) found that hedgerows which were kept between 1 and 2 m tall had a higher species richness of butterflies than shorter hedgerows, but that hedgerows less than 1 m tall had a higher abundance of butterflies than hedgerows over 2 m tall. The species richness of butterflies was higher on hedgerows which were 1–2 m tall than on hedgerows which were less than 1 m tall (data presented as model results). However, the abundance of butterflies was higher on hedgerows which were <1 m tall than on hedgerows which were >2 m tall (data presented as model results). See paper for details on individual species groups. Hedgerows were divided into four height categories (<1 m, 1–2 m, 2–3 m, >3 m). From April–September 2014–2015, butterflies were surveyed along 44 transects, divided into 8–26 × 50-m sections. In 2014, thirty transects were surveyed once/month, and in 2015 fourteen different transects were surveyed twice/month. Only transect sections along hedgerows were included (number not specified).

    Study and other actions tested
  15. A replicated, randomized, paired, controlled study in 2010–2015 on a farm in Devon, UK (Staley et al. 2018, same experimental set-up as Staley et al. 2016) found that hedges which were cut once every two or three years in autumn, and allowed to increase in size with each successive cut, had more brown hairstreak Thecla betulae eggs than hedges cut every year, in winter or to a standard size. Over four years, the total abundance of eggs on hedges cut to allow incremental growth (5–12 eggs) was higher than on hedges cut to a standard size (2–6 eggs). When cut in autumn, there were more eggs on hedges cut once every three years (6–12 eggs) than on hedges cut every year (2–6 eggs). Hedges cut once every two (3–11 eggs) or three (6–12 eggs) years in autumn had more eggs than hedges cut every two (3–5 eggs) or three (3–6 eggs) years in winter. Hedges which were not cut for five years had a total of 5 eggs on average. In January–February 2010, three 195-m-long hedges were cut. From September 2010, the hedges were divided into thirteen 15-m sections, to which each combination of three sets of management options were applied for five years: cut once every one, two or three years; cut in September or January/February; and cut to the same dimensions or with the cutting bar raised by 10 cm on each successive cut. A section at the end of each hedge was left uncut throughout the experiment. In February–March 2012–2015, brown hairstreak eggs were surveyed by searching all blackthorn stems and shoots in the central 10 m of each hedge section for 20 minutes on each side of the hedge.

    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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Butterfly and Moth Conservation

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Butterfly and Moth Conservation
Butterfly and Moth Conservation

Butterfly and Moth Conservation - Published 2022

Butterfly and Moth Synopsis

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