The Upland Sandpiper (Bartramia longicauda) is a large shorebird that inhabits open grasslands across North America. Its habitat requirements and preferences provide insight into the ecosystems it relies on.
Grasslands
The Upland Sandpiper is strongly associated with grasslands, especially native prairie. It avoids agricultural lands and pastures with dense, tall vegetation. The bird prefers grasslands with a mix of short and mid-height grasses, forbs (broadleaf herbaceous plants), and bare ground. This diverse structure provides openings for foraging and detecting predators, as well as vertical structure for song perches and nest sites.
Upland Sandpipers use grasslands ranging from very arid to sub-humid and spanning multiple ecoregions. Across this range, native prairie provides optimal habitat. In tallgrass prairie, Upland Sandpipers favor areas where grazing or fire maintains vegetation heterogeneity. They are less common in unmanaged tallgrass prairie overgrown with dense, tall grasses and few forbs. In mixed-grass and shortgrass prairies of the Great Plains, lightly or moderately grazed areas provide suitable habitat structure. Shrub encroachment, resulting from fire suppression and grazing changes, reduces habitat suitability in many prairies.
Breeding Habitat Composition
On the breeding grounds, Upland Sandpipers use native prairies as well as some planted grasslands. In Wisconsin, birds were consistently more abundant in remnant prairie than in Conservation Reserve Program (CRP) grasslands. Remnant prairie averaged 61% grass cover, 12% forb cover, 23% litter, and 5% bare ground. CRP fields had thicker vegetation, averaging 84% grass cover, 5% forb cover, 9% litter, and 2% bare ground. Greater bare ground on prairies provides open space for displaying and foraging.
In Minnesota, spring densities were highest in dry prairie (0.36 birds/ha) and planted grassland (0.22 birds/ha), lower in wet prairie (0.11 birds/ha), and lowest in hayland (0.02 birds/ha). Dry prairie and wet prairie sites had average vegetation heights of 38.4 cm and 62.6 cm respectively. Haylands had the tallest and densest vegetation at 82.2 cm height. These results demonstrate the species’ preference for moderate vegetation height and density.
Nesting Habitat Composition
Upland Sandpiper nests are scrapes lined with grasses, forbs, leaves, and stems and placed on the ground in open habitat. Nests are typically hidden by surrounding vegetation. Documented nest sites have been found in grass cover ranging from very short ()5 cm) grazed grasslands up to tallgrass prairie sites averaging 50-60 cm vegetation height.
In grazed mixed-grass prairie in North Dakota, average vegetation height at 29 nests was 16.5 cm and average visual obstruction (density) was 1.6 dm. The most common plant species around nests were porcupine grass (Stipa spartea), threadleaf sedge (Carex filifolia), and fringed sagewort (Artemisia frigida). Bare ground cover averaged 24% near nests.
At nest sites in Wisconsin, average vegetation height was 18 cm and litter depth was 1.6 cm. Dominant plants were Kentucky bluegrass (Poa pratensis), smooth brome (Bromus inermus), and big bluestem (Andropogon gerardii). These sites had 33% grass cover, 30% forb cover, 29% litter cover, and 7% bare ground on average.
Brood-rearing Habitat Composition
After hatching, Upland Sandpiper chicks leave the nest within hours and rely on their cryptic down to hide in grasslands. Parents lead chicks to habitats with adequate cover to conceal small chicks as well as openings for foraging on invertebrates. Vegetation height used for brood-rearing varies across the species’ breeding range.
In grazed mixed-grass prairie in North Dakota, average vegetation height at brood locations was 20.5 cm, compared to 16.5 cm at nests. Vegetation density was higher at brood sites as well, averaging 4.8 dm obstruction. Porcupine grass and threadleaf sedge remained common, along with willowweed (Persicaria lapathifolia). Bare ground decreased near broods to an average of 14%.
In Wisconsin remnant prairies, sites used for brood-rearing had higher litter depth (5 cm vs. 1.6 cm at nests). Vegetation composition was similar, although brood sites had slightly higher litter cover (36% vs. 29% at nests) and lower bare ground (2% vs. 7% at nests). Both nesting and brood-rearing habitats provided adequate overhead cover while also allowing chicks to move through the vegetation.
Modified Habitats
In addition to native prairies, Upland Sandpipers use some human-modified grassland habitats. Birds breed in pastures as well as retired croplands planted with grasses for conservation programs. However, vegetative structure strongly influences whether modified habitats are suitable replacements for native grasslands.
Pastures
Lightly grazed pastures can mimic grassland vegetation structure utilized by Upland Sandpipers. Rotational grazing or moderate season-long grazing provides habitat, while heavy continuous grazing reduces suitability by lowering vegetation height and diversity. Hayed pastures are avoided in the early nesting season due to the lack of concealing cover.
In Wisconsin, spring bird densities were significantly higher in rotationally grazed pastures (averaging 2 birds/40 ha) than continuously grazed pastures (0.1 birds/40ha). Vegetation measurements showed rotationally grazed sites had higher forb cover and greater structural heterogeneity than continuously grazed pastures. Well-managed cattle pastures can thus provide habitat, especially in landscapes where little native prairie remains.
Conservation Reserve Program Lands
Introduced grasses planted on retired croplands under the Conservation Reserve Program (CRP) can vary widely in habitat suitability for Upland Sandpipers. CRP fields with introduced warm-season grasses, like switchgrass (Panicum virgatum), provide better habitat than exotic cool-season grasses. Warm-season grasses provide habitat structural diversity, especially when fields are periodically burned or lightly disked.
In Illinois, Upland Sandpiper densities were significantly higher in CRP fields seeded with switchgrass and native mixes than exotic cool-season grasses. Mixed stands of native warm-season grasses averaged 1.5 birds/40 ha. Cool-season grasses, like smooth brome, were used significantly less, averaging 0.1 birds/40 ha. Management regimes also influenced use: spring-burned CRP fields had four times higher sandpiper densities than idled fields.
A comparison of CRP lands and Waterfowl Production Areas in North Dakota found birds more than twice as abundant in protected grasslands (1.01 birds/40 ha) than CRP fields (0.45 birds/40 ha). Both habitat types provided breeding habitat, but native prairie appears able to support higher densities.
Non-breeding Habitat Composition
During the non-breeding season, Upland Sandpipers occupy open native grasslands, pastures, and agricultural fields across southern South America. Birds winter from southern Brazil through Uruguay, Paraguay, Argentina, and Chile. Habitat use varies across this broad migratory range.
Pampas Grasslands
In the fertile South American Pampas, Upland Sandpipers occur primarily in pastures and croplands. Densities are highest in more lightly grazed pastures with greater vegetation structural heterogeneity. In croplands, they forage in soybean and corn fields and stubble after harvest.
In the Flooding Pampas grasslands of Argentina, wintering Upland Sandpipers preferentially used pastures over croplands. Densities were five times higher in pastures with lower, sparser vegetation cover and high plant diversity. Complex vegetation structure provides roost sites and increases prey availability. Agricultural lands here provide some habitat but generally support lower densities.
Southern Cone Grasslands
Further south in the grasslands of the Southern Cone region, croplands become less extensive. Here Upland Sandpipers occur in higher densities in native grasslands during the non-breeding season. Patagonian grasslands in Argentina supported four times higher densities than agricultural lands in one study.
Vegetation structure varies more widely in these grasslands compared to the homogenous Pampas region. Birds prefer sites with moderate vegetation height and density, avoiding very short or tall grass. A diversity of grasses, forbs, and bare ground offers roosting structure and insect prey resources. Native grasslands meeting these criteria provide the highest quality non-breeding habitat.
Conservation Implications
The Upland Sandpiper evolved in dynamic prairie ecosystems maintained by grazing, fire, and climate fluctuations. Human land use has greatly altered remaining grasslands, yet studies show properly managed grasslands can continue to provide habitat. Both breeding and non-breeding populations benefit from native prairie preservation and restoration.
On the breeding grounds, focus should be on preserving large remnant prairies under ecological management regimes. Grazing, prescribed fire, and rest are important tools for maintaining heterogeneity. Small reconstructed prairies also benefit the species, especially when connected to larger prairie tracts.
In agricultural landscapes, pasture management and conservation programs like CRP provide opportunities for habitat creation. Light rotational grazing, warm-season grasses, periodic disturbance through fire or disking, and structural diversity will improve suitability. Grassland conservation and management across public and private lands can benefits Upland Sandpipers populations.
In South American grasslands, habitat loss continues to threaten non-breeding and migrating Upland Sandpipers. Prevention of native grassland conversion to soybean and other croplands is a high priority. Sustainable cattle grazing regimes can maintain suitable habitat structure in native pastures.
For grassland birds like Upland Sandpipers, both breeding and non-breeding habitat availably shapes populations. Research on habitat preferences helps guide targeted conservation programs and practices tailored to this species of conservation concern.