Providing evidence to improve practice

Action: Restore or create grasslands Bird Conservation

Key messages

  • Of 23 studies found, three from the USA, Canada and Iceland found that species richness on restored grassland sites was similar to remnant habitats or higher than unrestored sites. One replicated, randomised study from the USA found that bird diversity was lower on restored grassland sites compared to hayfields or pastures, whilst a small American study found that species richness declined at one of two fields restored to grassland from croplands. Three studies from the USA found that target species used restored grasslands.
  • Two studies from the USA found that CRP fields held disproportionate proportions of total bird populations, or that local population trends were correlated with the amount of CRP land in the area. Six studies from the USA and UK found that the abundances or densities of some, or all, species were higher on restored sites compared to unrestored sites, or were comparable to natural habitats. Two studies found lower abundances of species on restored sites compared to unrestored sites, although the authors of one suggest that drought conditions may have confounded the results.
  • Five studies from the USA found that at least some bird species in restored areas of grassland had higher productivities than birds in unrestored areas; similar or higher productivies than natural habitats; or had high enough productivities to sustain populations. Three studies found that productivities were lower in restored areas than unrestored, or that productivities on restored sites were too low to sustain populations.
  • A replicated study from the USA found that older CRP fields held more nests, but fewer species than young fields. Two replicated American studies found no differences in species richness or abundances between CRP fields and riparian filter strips whether they were sown with warm- or cool-season grasses, whilst another found that more grassland specialist species were found on sites sown with non-native species. A replicated study from the USA found no difference in bird densities between sites seeded with redtop grass and those not seeded. A study from Iceland found that very few birds were found on restored sites, unless they were sown with Nootka lupin.

 

Supporting evidence from individual studies

1 

A small 1967 study in Maryland, USA (Burger & Linduska 1967), investigated the impact of grassland restoration, as well as other interventions, on northern bobwhites Colinus virginianus and found that the population on the farm increased from five to 38 coveys in eight years. This study is described in detail in ‘Threat: Agriculture – Plant new hedges’.

 

2 

A small study over the summers of 1973-1975 in two former corn and soybean fields (16 and 12 ha respectively) in South Dakota, USA (Blankespoor 1980), found that species richness and abundance declined over the study period, after the fields were planted with six species of native grasses in 1971. In the old corn field, species richness declined from 11 to 5 species and total abundance declined from 80 to 22 individuals/ha. Similarly, total abundance declined from 71 to 28 in the old soybean field but species richness remained at 6-7 species per year. Grasshopper sparrows Ammodramus savvanarum were the most abundant birds in the old corn fields whereas dickcissels Spiza americana were most abundant in the old soybean field. The author pointed out that the results may have been confounded by drought conditions. Species richness was comparable between restored and mature grasslands.

 

3 

A replicated, controlled study in 1978-1980 on a 41.5 ha reclaimed coal mine site in West Virginia, USA (Wray et al. 1982), found that clutch sizes of grasshopper, savannah Passerculus sandwichensis, vesper Pooecetes gramineus and field sparrows Spizella pusilla were similar to those reported for natural grasslands but nest predation rates were high and the main cause of nest failure in all years. Of 185 nests located, 80 (43%) were thought to be predated. Thus, although providing new habitat, low reproductive success suggests that the grassland may not benefit sparrow populations as immigration will be necessary to maintain breeding numbers.

 

4 

A replicated, controlled study in the summers of 1992-1993 in North Dakota, USA (Johnson & Igl 2005), found that the 11 of 18 bird species recorded occurred at higher densities in CRP fields, compared to non-CRP fields. CRP fields only covered 7% of land in North Dakota but supported a disproportionate amount of the total state populations of sedge wren Cistothorus platensis (27%), savannah sparrow (23%), grasshopper sparrow (22%), bobolink Dolichonyx oryzivorus (19%) and lark bunting Calamospiza melanocorys (18%).

 

5 

A replicated, controlled study from April-June in 1990-1991 in Kansas, USA (Granfors et al. 1996), found that eastern meadowlark Sturnella magna nest survival and productiuvity did not differ between four CRP fields (18-24 ha) planted with six native grass species in 1988-1989 and eight rangeland sites (14-259 ha) with a history of spring burning (93 and 95% daily survival rate; 1.9 and 0.7 fledglings / female for CRP and rangeland fields respectively). Overall, nest success averaged 14 and 24% for CRP and rangeland fields respectively. Predation was the primary source of nest failure in CRP fields (37 compared to 25% for CRP and rangeland fields respectively). Mowing CRP fields was a source of nest failure and abandonment. Mowing was conducted (without removing cut material) to control weeds in 1990 and one field was mowed only in selected strips.

 

6 

A replicated study in summer 1992 in 19 CRP fields in Michigan, USA (Millenbah et al. 1996), found that more bird nests were found in older fields and that they had higher survival rates than those in younger fields (average of 22-23 nests/field and 28-29% survival for nine 4-5 year-old fields vs. 10 nests/field and 14% survival for three one year-old fields). However, bird species diversity was higher in one-year old fields, compared with four or five year-old fields. Bird abundance varied over time, with no clear pattern. A total of 32 bird species were recorded, with red-winged blackbirds Agelaius phoeniceus, song sparrows Melospiza melodia, bobolinks and sedge wrens being the most common. The majority of nests (83% of 166) found were red-winged blackbirds’.

 

7 

A replicated study from May 1991 to March 1995 in an agricultural landscape in Nebraska, USA (Delisle & Savidge 1997), found that species richness and abundance did not differ between five fields planted with cool-season, non-native, grasses and legumes and five planted with warm-season native grasses (all planted between 1987-1988; all between 20-40 ha). Dickcissels and grasshopper sparrows were the most abundant species during the breeding season (49-78% of total bird abundance). Common yellowthroats Geothlypis trichas and sedge wrens were more abundant on warm-season fields. American tree sparrows Spizella arborea were the most abundant native species during winter and were more abundant on warm-season fields. Bobolinks were significantly more abundant on cool-season fields, as were meadowlarks Sturnella spp. during winter.

 

8 

A study in Illinois, USA (Herkert 1997), found that the population trends of Henslow’s sparrow Ammodramus henslowii in 1987-1995 were positively correlated with the proportion of the counties’ land in the CRP. Between 1975 and 1995 the Henslow’s sparrow population in Illinois declined by over 7% a year, but the three counties with the highest proportion of CRP land (7-9%) showed large (>50% a year) population increases. In total, Henslow’s sparrows were recorded in 27 of 102 counties.

 

9 

A replicated, controlled study in the winters of 1994-1997 on farmland in southern England (Wakeham-Dawson & Aebischer 1998) found that Eurasian skylarks Alauda arvensis, corn buntings Miliaria calandra and meadow pipits Anthus pratensis were consistently more abundant on arable fields reverted to species-rich chalk grassland (36-37 fields surveyed annually) than on land reverted to permanent grassland (71-80 fields sown with agricultural grasses), intensively managed permanent grassland (12-17 fields) or winter wheat (23-33 fields) fields (25-230 birds/km2 for skylarks on reverted chalk grassland vs. 0-11 birds/km2 for other field types; 0.9-4.7 birds/km2 vs. 0-1 birds/km2 for buntings and 4-6 birds/km2 vs. 0-4 birds/km2 for pipits). Densities of rooks Corvus frugilegus did not differ across field types. Reverted chalk grassland fields were sown with species such as Festuca spp. and Bromus spp. grasses.

 

10 

A replicated, controlled study in spring and summer 1994-1996 on 40 farms in southern England (Wakeham-Dawson et al. 1998) found that arable fields reverted to species-rich chalk grassland consistently held higher densities of Eurasian skylarks than land reverted to permanent grassland (sown with agricultural grasses), intensively managed permanent grassland or winter wheat fields (12.0-22.8 skylarks/km2 for 16-35 reverted chalk grassland fields vs. 2.6-11.9 skylarks/km2 for 16-82 fields of other types). Densities of carrion crows Corvus corone and rooks C. frugilegus were not consistently higher on any field type (1-2 crows/km2 and 0-14 rooks/km2 for chalk grassland vs. 0-2 crows/km2 and 0-89 rooks/km2 for other fields). Reverted chalk grassland fields were sown with Festuca spp. and Bromus spp. grasses.

 

11 

A replicated study from 1993-1995 in a mixed prairie-cropland landscape in Missouri, USA (McCoy et al. 1999), found that some bird species appeared to be able to maintain stable populations on 16 restored grassland fields (eight sown with cool-season and eight with warm-season grasses), while others might not. Productivity exceeded levels necessary for population growth for four grassland species (average of 4.fledglings/nest and 3 female nestlings/nest), but not for two others (average of 3.fledglings/nest and 1 female nestlings/nest). Results were uncertain for one species (average of 4 fledglings/nest and 1 female nestlings/nest). Although large numbers of dickcissels and red-winged blackbirds nested in restored fields, there was little evidence that grass restoration contributed to their population expansion.

 

12 

A replicated study in the breeding seasons of 1997-1998 at 19 reclaimed coal mine sites, totalling 11,500 ha of grassland, in southwest Indiana, USA (Bejema et al. 2001), found that 200-300 singing male Henslow's sparrows were recorded on unmanaged grassland (density estimates averaging 0.2/ha) but they avoided areas of sparse or short vegetation prevalent in grazed pastures and hayed fields.

 

13 

A replicated, controlled study from May-July in 1998 in 629 restored grassland sites and 564 cropland sites (distributed amongst 81 eco-region clusters) in prairie habitat in Alberta, Saskatchewan and Manitoba, Canada (McMaster & Davis 2001), found that the average species richness was significantly higher in restored grassland  (PCP) sites than at cropland sites (2.5 compared to 1.3 species/site). Of the ten most common species, nine were found significantly more frequently at restored grassland sites, whereas just one occurred more frequently in cropland. Amongst restored grasslands, average species richness did not differ between hay and pasture sites but four species occurred more frequently in hay sites and two different species more often on pastures. Restored grasslands (planted in the early 1990s) comprised a combination of wheatgrass Agropryon spp., brome grass Bromus spp. and alfalfa Medicago spp. Cropland sites consisted of annually cultivated fields (mainly wheat).

 

14 

A replicated, randomised and controlled before-and-after trial study from May-July in 1992-1997 in North Dakota, South Dakota and Montana, USA (Reynolds et al. 2001), found that the nest success and reproductive rate of mallards Anas platyrhynchos, gadwalls A. strepera, blue-winged teals A. discors, northern shovelers A. clypeata and northern pintails A. acuta on 335 10.4 km2 plots increased significantly following the conversion of plots to perennial grassland by 1992. Estimated nest success and recruitment rates of the five species were 46% and 30% higher than in croplands. Mallard and blue-winged teal showed the largest (38 and 32% respectively) and gadwall showed the smallest (21%) gains in recruitment rate after restoration. Nest success was positively correlated with total planted grass cover in plots for all species except northern shoveler. Daily survival rate of duck nests in croplands from a pre-existing dataset from 1980-1984 (pre-restoration) and 1990-1994 (restoration) were used to compare treatment effects.

 

15 

A replicated study in May-July 1997-1998 in southwest Indiana, USA (DeVault et al. 2002), found that a total of 28 breeding bird species were recorded on 19 reclaimed surface coal mine grasslands. The 20 ‘common species’ (i.e. present at 68-100% of sites), included five grassland specialists. Red-winged blackbird, eastern meadowlark Sturnella magna and grasshopper sparrow were most abundant (the latter two being grassland specialists). Seven other grassland species were present (11-42% of sites) but were uncommon. Sites were 110-3,180 ha and seeded with non-native Eurasian grasses.

 

16 

A replicated, controlled study from May-July in 1999-2000 in ten grasslands restored in 1987 and ten native tallgrass prairie fields in an agricultural landscape in Iowa, USA (Fletcher & Koford 2002), found that bird species richness was similar between restored and native habitats (average of 7 species/site). Densities of eight common bird species were similar over the study period except for grasshopper sparrows and savannah sparrows, which were higher in restored grasslands (both 0.1 males/ha in native grassland vs. 0.7 and 0.3 males/ha in restored grasslands). Most species had lower densities in landscapes with high edge habitat density. Grasslands contained both warm-season (switchgrass Panicum virgatum, big bluestem Andropogong erardii or both) and cool-season grass plantings (smooth brome Bromus inermis or grass-alfalfa Medicago sativa mixtures). Restored fields averaged 57 ha and prairie fields 54 ha.

 

17 

A replicated study at 19 reclaimed mine sites in southwest Indiana, USA (Scott & Lima 2004), found that grassland specialist species (e.g. grasshopper sparrow and Henslow’s sparrow) were found in greater breeding abundance at sites dominated by non-native grasses and were less common on those rich in forbs. Non-specialist bird species showed no significant preference.

 

18 

A replicated study from May-July in 2001-2002 in 33 corn and soybean fields containing riparian filter-strips (all ? 200 m long and > 1 km apart) in Iowa, USA (Henningsen & Best 2005), found that species richness and abundance of grassland birds was similar between strips planted with warm-season grasses, compared to cool-season grasses, but that strips next to woody streamside vegetation held fewer species (6/site) than those with adjacent non-woody vegetation (8 species/site). Nest success was low in all treatments (only 27% of nests fledged at least one nestling) due chiefly to predation (85% of all nests). Cool-season species included brome grass, orchard grass Dactylis glomerata and timothy Phleum pratense; warm-season strips were planted mainly with switchgrass Panicum virgatum.

 

19 

A replicated controlled study in the breeding seasons of 2000-1 in two restored-mine grasslands and two control (unmined) grasslands (8-18 ha) in Kentucky, USA (Monroe & Ritchison 2005), found that Henslow’s sparrow territory size was generally smaller on restored grasslands (on 1 May, 0.29 ha/territory for 25 nests on restored sites vs. 0.34 ha/territory for 18 nests on control sites; 15 July: 0.33 ha/territory for 25 nests vs. 0.45 for 17). Average clutch size (3.8) and average number of fledglings per nest (of 48 nests, 28 fledged at least one young) were similar between sites. More insect prey was present on the reclaimed sites.

 

20 

A replicated, controlled study from March-May 2001-2 in two riparian oak forest sites in Missouri, USA (Furey & Burhans 2006), found that red-winged blackbird territory area and density were similar between four blocks planted with oak seedlings and seeded with redtop grass Agrostis gigantean and those not seeded (1,657 m2/territory and 0.6 territories/ha for two seeded blocks vs. 1,852 and 0.6 for unseeded blocks). This study is discussed in more detail in ‘Restore or create forests’.

 

21 

A study in 1999-2000 on the reclaimed Chinook mine (39-67 ha) and Universal mine sites in southwest Indiana, USA (Galligan et al. 2006), found 465 bird nests of 31 species at Chinook and 446 at Universal. Red-winged blackbird, eastern meadowlark, field sparrow, dickcissel, grasshopper sparrow and Henslow's sparrow were the commonest nesting birds. Reproductive success (i.e. nests that fledged young) of key species, e.g. Henslow's sparrow (9 of 21 nests fledged young) and grasshopper sparrow (26 of 41), and of several other species was comparable with that in non-mined grassland habitats. Both sites were seeded with (mostly) non-native grasses and were situated in open grassland; shrub/savanna; and grassland with patches of shrubs.

 

22 

A before-and-after study in southern Iceland in 2009 (Gunnarsson & Indridadottir 2009) found that eight species of birds were found in the study site following the revegetating of ‘sandplains’, but no birds were found in barren sandplains or strips of lyme grass Leymus arenarius. Meadow pipits Anthus pratensis, common snipe Gallinago gallinago and redshank Tringa totanus were the most common species and found at highest abundances in dense areas of Nootka lupin Lupinus nootkathensis (210 meadow pipits/km2, 46 snipe/km2 and 19 redshank/km2 vs. 83 pipits/km2 and 13 snipe/km2 in areas of scattered lupins). Only meadow pipits were found in any habitat without lupins. Revegetation began in earnest in 1988, when areas were sown with lyme grass (65 kg seeds/ha), followed by lupin strips from 1992 (4 kg seeds/ha) and non-native grasses. All treatments except lupins were also fertilised.

 

23 

A replicated, randomised, controlled study from May-July in 2004-2005 in Kansas and Oklahoma, USA (Rahmig et al. 2009), found that overall bird diversity and evenness was significantly higher in ten native prairie hayfields (both burned and unburned) and 18 grazed pastures than eight grass-restored fields. Seven species were recorded and three analysed: dickcissel density was highest in restored fields but nest success was highest and nest parasitism lowest in unburned hayfields (48% compared to 16% on average in other sites). Conversely, grasshopper sparrow density was highest in grazed pastures but nest success was lowest in these pastures and highest in burned hayfields (57% compared to 12% on average in other sites). Management did not influence density and nest survival of eastern meadowlarks, which were uniformly low across the region.

 

Referenced papers

Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2017) Bird Conservation. Pages 95-244 in: W.J. Sutherland, L.V. Dicks, N. Ockendon & R.K. Smith (eds) What Works in Conservation 2017. Open Book Publishers, Cambridge, UK.