Modify grazing regime: Forest, open woodland & savanna
Overall effectiveness category Awaiting assessment
Number of studies: 7
Background information and definitions
Grazing by livestock changes habitats by reducing vegetation height and ground cover, altering plant abundance and diversity, creating openings for seed growth and preventing reed or shrub growth. While heavy grazing by some wild grazers can have detrimental effects on reptile populations (Howland et al. 2014), the result of different grazing regimes on reptiles will likely depend on the reptile species, grazing intensity and the timing of grazing activity. Studies included in this intervention measure the impacts of varying intensities of grazing or different types of grazing regimes on reptiles. Studies that just compare the effect of stopping all grazing to continued grazing are included under the intervention Cease livestock grazing.
For interventions that aim to reduce the detrimental effects of grazing by wild herbivores see Threat: Invasive or problematic species - Remove or control invasive or problem herbivores and seed eaters.
Howland B., Stojanovic D., Gordon I.J., Manning A.D., Fletcher D. & Lindenmayer D.B. (2014) Eaten out of house and home: impacts of grazing on ground-dwelling reptiles in Australian grasslands and grassy woodlands. PLoS One, 9, e105966.
Supporting evidence from individual studies
A replicated, site comparison study in 1978–1979 in broadleaf forest in western Arizona, USA (Jones 1981) found overall lizard abundance but not diversity was higher under lighter compared to heavier grazing regimes. Lighter grazed plots had higher abundances of lizards compared to heavier grazing in cottonwood-willow (Light grazing: 1.1 individuals/trap group/night; heavy grazing: 0.6). Species diversity was statistically similar between lightly and heavily grazed sites across all vegetation sites (result presented as diversity index). See paper for details of individual species abundances. Seven lightly grazed and seven heavily grazed plots were established in areas of cottonwood-willow. Lightly grazed sites were characterised by a lack of livestock and good habitat condition. Heavily grazed sites were characterised by cattle trails, presence of livestock and poor habitat condition. Abundance and diversity (Shannon-Wiener Index) were estimated using drift fences with four pitfall traps in March–June and September–November 1978 and March–October 1979.Study and other actions tested
A paired, site comparison study in 2006–2007 in grassy woodland and agricultural land in south eastern Australia (Dorrough et al. 2012) found that rotational grazing did not increase reptile abundance compared to continuous grazing. Reptile abundance was similar in rotationally grazed plots (2.0 reptiles/ha) compared to continuously grazed plots (1.7 reptiles/ha), but greater in grazed plot with trees (3.6 reptiles/ha) than in grazed native pasture plots (1.4 reptiles/ha) regardless of grazing system. Twelve pairs of farms of with either rotational or continuous grazing (cattle or sheep) on native pastures were selected. Rotational grazing systems (four or more paddocks grazed for <56 days at a time followed by at least 21 days of rest with more rest time than grazing time) had operated for at least five years. Paddocks on continuous grazing farms were stocked for >6 months a year. Reptiles were surveyed in two 1 ha plots/farm (one in treed and one in cleared pastureland, 48 plots in total) using coverboards and active searches in December 2006, March 2007 and October 2007.Study and other actions tested
A replicated, randomized, before-and-after study in 1999–2004 in open eucalyptus savanna in north-eastern Queensland, Australia (Kutt et al. 2012) found that different cattle stocking regimes had mixed effects on reptile abundance depending on the species. All results presented as model outputs. At medium stocking rates, dubious gecko Gehyra dubia and shaded-litter rainbow skink Carlia munda abundances increased over time. At high cattle stocking rates, terrestrial gecko Diplodactylus conspicillatus and north-eastern firetail skink Morethia taeniopleura abundances decreased over time. At medium and high stocking rates, Binoe’s prickly gecko Heteronotia binoei abundance increased, but decreased in variable/rotational stocking over time. Some species’ abundances varied depending on vegetation type (see paper for details). Sixteen 1 ha plots were established (>500 m apart) in a commercial livestock station (1,041 ha). Plots were grazed at moderate stocking (4 plots), heavy stocking (4 plots), or rotational/variable stocking rates (8 plots, see paper for details). Ground cover was either mainly silverleaf ironbark Eucalyptus melanophloia (8 plots) or reid river box Eucalyptus brownii (8 plots). Reptiles were surveyed in November–April and May–October in 1999–2000 and 2003–2004 using drift fences with pitfall traps and visual encounter surveys. All plots were prescribed burned in 1999 and a second fire took place in the ironbark-dominated rotational/variable stocking plots in November 2001.Study and other actions tested
A replicated, site comparison study in 2011–2013 of 29 farms in south-eastern Australia (Kay et al. 2017) found that different grazing treatments had varying effects on the colonisation and extinction probabilities of three of six lizard species. Results are reported as statistical model outputs. Two lizard species (Boulenger’s snake-eyed skink Morethia boulengeri and southern rainbow-skink Carlia tetradactyla) were more likely to colonize patches with modified low or high rotational grazing than prolonged high rotational or continuous grazing. The opposite was true for straight-browed ctenotus Ctenotus spaldingi, which was more likely to become extinct in patches with modified high and low rotational grazing. Colonisation and extinction probabilities for three other lizard species (ragged snake-eye skink Cryptoblepharus pannosus, Victoria three-toed earless skink Hemiergis talbingoensis, marbled geckos Christinus marmoratus) were not significantly affected by the grazing treatments. A total of 97 sites were surveyed on 29 farms (2–4 sites/farm with different grazing treatments) within a grazing-dominated landscape. Each site used one of four grazing treatments: modified low rotational grazing (<5 years of long-duration rotational grazing following previous continuous grazing); modified high rotational grazing (<5 years of high intensity short-duration grazing following previous continuous grazing); prolonged high rotational grazing (high-intensity short-duration grazing for >10 years); continuous grazing for >10 years. Grazing was mainly by sheep Ovis aries and cattle Bos taurus. Searches were carried out for reptiles in natural habitat and artificial refuges in two plots (0.4 ha) within each site in September 2011, 2012 and 2013.Study and other actions tested
A replicated, paired, site comparison study in 2014–2015 in 12 pastures adjacent to open grassy woodland in New South Wales, Australia (Pulsford et al. 2017) found that rotational grazing did not increase reptile abundance or species richness compared to continuous grazing. Over one year, farms with rotational grazing did not have higher reptile abundance or species richness than farms with continuous grazing (data not provided). One lizard species, Amphibolurus muricatus (common name Jacky dragon not given in study) was more likely to be present in sheep-grazed rather than cattle-grazed paddocks (results presented as statistical model outputs, see paper for details). Reptiles caught were mostly skinks (Scincidae spp.). In January 2014–March 2015, reptiles were surveyed in 12 farms grazed by sheep Ovis aries or cattle Bos taurus in paddocks directly adjacent to remnants of native open grassy woodland. Five farms had a rotational grazing regime (livestock moved between paddocks every few days and not returning to the same place for weeks or months), and seven had a continuous grazing regime (livestock left in same paddock for extended periods). Surveys were carried out using drift fences, pitfall traps and funnel traps set at 20, 50 and 80 m intervals along 180 m transects that extended from the native woodland into the grazing pasture. Surveys took place for 5 days at a time in austral spring–summer.Study and other actions tested
A replicated, site comparison study in 2013 in restored eucalypt woodland on 25 farms in New South Wales, Australia (Lindenmayer et al. 2018) found that in replanted native vegetation, areas with occasional livestock grazing or no grazing had higher reptile species richness than areas with continuous grazing. Results all reported as model outputs. The authors reported that reptile species richness was higher where the amount of leaf litter was greater and that leaf litter was reduced in plots that were continuously grazed. Fifteen reptile species were recorded. In austral spring 2013, sixty-one plots of replanted native vegetation on 25 farms were surveyed in a 150 x 120 km agricultural area in the South Western Slopes (time since replanting: 6–61 years). Ten plots each were either occasionally grazed or continuously grazed by cattle Bos taurus or sheep Ovies aries (20 plots total) and a further 41 plots were never grazed. Reptiles were surveyed in each plot using 20 minute active searches and groups of artificial refuges (corrugated steel, railway sleepers and concrete roof tiles, two groups/plot).Study and other actions tested
A replicated, site comparison study in 2015 in eucalyptus woodland in Queensland, Australia (Nordberg et al. 2018) found that decreasing cattle grazing intensity decreased dubious four-clawed geckos Gehyra dubia abundance but did not change inland snake-eyed skink Cryptoblepharus australis abundance. Four-clawed gecko abundance was generally lower at lower grazing intensity compared to higher grazing intensity (moderate stocking: 5 geckos/plot; rotational stocking regime: 6 geckos/plot; variable stocking: 12 geckos/plot; heavy stocking: 10 geckos/plot). Inland snake-eyed skink abundance was similar at all grazing intensities (moderate stocking: 3 lizards/plot; rotational stocking: 4 lizards/plot; variable stocking: 5 lizards/plot; heavy stocking regime: 5 lizards/plot;). Data was collected in eight 100 ha paddocks each with one of four grazing regimes (two replicates of each). The grazing regimes increased in intensity from moderate to rotational to variable to heavy stocking rates (see original paper for details). Each paddock contained three sampling sites. Lizards were monitored during seven days in February 2015 using arboreal coverboards and spotlighting. Faecal samples were collected from lizards captured by hand.Study and other actions tested