Use mixed stocking

Overall effectiveness category Awaiting assessment
Number of studies: 3
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Background information and definitions

Livestock prefer to eat different plants, and graze at different heights or in different patterns. For example, sheep graze to a uniform height, while cattle leave heavily trampled areas and eat grass in clumps, leaving patches of taller vegetation (Schultz et al. 2008). These grazing patterns encourage different vegetation communities to develop, with different plants dominating. Therefore, grazing with a mix of livestock, rather than just one type, may encourage a more diverse community of butterflies and moths, with individual species preferring the patches created by particular grazers.

This action includes studies comparing the use of multiple livestock types with single types of livestock. For studies comparing the use of different single types of livestock, see “Change type of livestock grazing”.

_{Schultz C.B., Russell C. & Wynn L. (2008) Restoration, reintroduction, and captive propagation for at-risk butterflies: A review of British and American conservation efforts. Israel Journal of Ecology & Evolution, 54, 41–61.}

Study locations

Key messages

Three studies evaluated the effects on butterflies and moths of grazing with mixed livestock. All three studies were in the UK and compared grazing with sheep and cattle to sheep only.

COMMUNITY RESPONSE (1 STUDY)

Richness/diversity (1 study): One replicated, randomized, controlled study in the UK found that grassland plots grazed at low intensity with sheep and cattle had fewer moth species than plots grazed at low intensity with sheep only.

POPULATION RESPONSE (3 STUDIES)

Abundance (3 studies): Two of three replicated studies (including two randomized, controlled studies and one paired, site comparison study) in the UK found that grassland plots grazed at low intensity with sheep and cattle had a similar abundance of moth caterpillars and small invertebrates including caterpillars to plots grazed at low intensity with sheep only. One of these studies found that in plots grazed at high intensity, the abundance of small invertebrates including caterpillars was lower in plots with sheep and cattle than in sheep only plots. The other study found that grassland plots grazed at low intensity with sheep and cattle had a lower abundance of adult moths than plots grazed at low intensity with sheep only.

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

A replicated, paired, site comparison study in 1989–1993 at an upland grassland in Scotland, UK (Dennis et al. 1998) found that plots grazed with sheep and cattle had a lower abundance of small invertebrates (including caterpillars) than plots grazed by sheep alone when grazing intensity was high, but there was no difference when grazing intensity was reduced. Heavily grazed plots with both sheep and cattle had fewer invertebrates (4–15 individuals) than plots grazed at high intensity by sheep alone (4–31 individuals). However, when grazing intensity was reduced there was no significant difference in the number of invertebrates between plots grazed by sheep and cattle (9–35 individuals) and sheep-only plots (6–39 individuals). Invertebrate abundance was highest at a fifth plot that was ungrazed (70–223 individuals). From 1989–1991, four experimental grazing plots (1–3 ha) were established. From May–October each year, the number of sheep/plot was adjusted weekly in order to maintain different sward heights (4.5 and 6.5 cm). From June–August, six yearling cattle were also grazed on two of the plots. From 1992, a fifth plot was left ungrazed. In August 1993, invertebrates were sampled from both tussocks and low sward at each of six randomly selected points/plot using a d-vac suction sampler.
Study and other actions tested
Referenced paper
Dennis P., Young M.R. & Gordon I.J. (1998) Distribution and abundance of small insects and arachnids in relation to structural heterogeneity of grazed, indigenous grasslands. Ecological Entomology, 23, 253-264.
A replicated, randomized, controlled study in 2003–2005 on an upland grassland in Perthshire, UK (Dennis et al. 2008, same experimental set-up as 3) found that mixed stocking did not affect the abundance of moth caterpillars under low intensity grazing. After 18 months of grazing, there was no significant difference in the number of caterpillars on lightly grazed mixed stocking (2.4 individuals/plot), sheep-only (1.9 individuals/plot), ungrazed (2.8 individuals/plot) and commercially grazed plots (2.3 individuals/plot). After 30 months, the number of caterpillars remained similar in the mixed stocking (2.4 individuals/plot) and sheep-only (1.9 individuals/plot) plots, but this was lower than in the ungrazed plots (4.9 individuals/plot) and higher than in the commercially grazed plots (0.5 individuals/plot). From January 2003, three grazing regimes (mixed: sheep and cattle equivalent to 0.9 ewes/ha; sheep-only: sheep at 0.9 ewes/ha; commercial: sheep at 2.7 ewes/ha) and an ungrazed treatment were replicated six times each in twenty-four 3.3-ha plots (in three pairs of adjacent blocks). Caterpillars were sampled by sweep net in 2003–2005.
Study and other actions tested
Referenced paper
Dennis P., Skartveit J., McCracken D.I., Pakeman R.J., Beaton K., Kunaver A. & Evans D.M. (2008) The effects of livestock grazing on foliar arthropods associated with bird diet in upland grasslands of Scotland. Journal of Applied Ecology, 45, 279-287.
A replicated, randomized, controlled study in 2003–2007 on an upland estate in Scotland, UK (Littlewood 2008, same experimental set-up as 2) found that plots grazed with sheep and cattle at low density had a lower abundance of moths and fewer moth species than plots grazed with sheep only at low density, but more moths than plots grazed by sheep at commercial stocking densities. On mixed grazing plots, both moth abundance (42 individuals/night) and species richness (11.3 species/night) were lower than on sheep-only plots grazed at the same low density (abundance: 52 individuals/night; richness: 12.3 species/night) and ungrazed plots (abundance: 48 individuals/night; richness: 13.2 species/night), but higher than on sheep-only plots grazed at commercial densities (abundance: 34 individuals/night; richness: 10.6 species/night). In January 2003, one of four grazing treatments was established on each of 24 plots (3.3 ha each) on a grazed acid grassland upland estate. The treatments were: low density mixed grazing (2 sheep/plot plus two cows and calves for 4 weeks in autumn); low density sheep grazing (3 sheep/plot); commercial high density sheep grazing (9 sheep/plot); ungrazed control. Moths were sampled between June and October 2007 using four 15 W light traps placed randomly within plots of each treatment, for six or seven sample nights/plot.
Study and other actions tested
Referenced paper
Littlewood N.A. (2008) Grazing impacts on moth diversity and abundance on a Scottish upland estate. Insect Conservation and Diversity, 1, 151-160.

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.