The northern bobwhite (Colinus virginianus) is a popular gamebird found throughout the eastern and central United States. Bobwhites nest on the ground in relatively open habitats with good cover. Their specific nesting locations and habitat preferences are important considerations for land managers aiming to conserve bobwhite populations. This article reviews what is known about where northern bobwhites build their nests and the habitat features that impact nest site selection.
Nesting cover requirements
Bobwhites require adequate ground cover for nesting. They generally do not nest in areas with very sparse vegetation or dense, woody cover. Ideal nesting habitat provides a balance between concealment from predators and openness needed for travel and foraging. Bobwhites often select nest sites with intermediate densities of grasses, forbs, shrubs, and litter.
Several key habitat factors impact bobwhite nest site selection and success:
Vegetation height and density
Bobwhites typically nest where herbaceous vegetation is relatively short and open at ground level but dense enough overhead to conceal the nest. Grasses and forbs 15-60 cm tall provide suitable overhead concealment in many habitats. Bobwhites tend to avoid nesting in very sparse or very dense, tall vegetation where nests are more visible to predators.
Ground litter
An accumulation of dead plant material (litter) on the ground aids nest concealment. Bobwhites often nest in clumps of litter at the base of bunchgrasses or forbs. Litter depth of 2.5-7.5 cm provides effective cover in many grassland habitats.
Bare ground
Some open ground around the nest allows easier travel to and from the nest site. Bobwhites select nest sites with intermediate amounts of bare ground, avoiding areas with extensive bare ground or dense plant cover at ground level. The optimal amount of bare ground varies by habitat and region.
Woody cover
Having some shrubs, trees, or brushy cover nearby provides escape cover from predators but thick woody vegetation decreases nest success. Brushy areas interspersed with open grasslands offer bobwhites proximity to protective woody cover for nesting.
Proximity to edge
Bobwhite nests are often located near habitat edges and ecotones between different cover types. Edge areas may provide a balance of concealment, openness, and quick access to refuges. For example, many nests are found near transitions between grassland and shrub or forest habitats.
Nest sites by habitat type
Bobwhites use a variety of habitat types for nesting, adapting to the plant species composition and structure available in different ecological regions and management regimes. Some details on typical nest sites in major habitat types:
Native grasslands
In native grasslands, bobwhites often nest at the base of clumps of bunchgrasses (such as bluestems and gramas) or grass-like plants (such as yucca). Nests are frequently placed under the edge of the plant clump with a canopy of dead leaves overhead. Native grass litter accumulations aid concealment.
Planted grasslands
In pastures, hayfields, CRP grasslands, and old-fields dominated by dense, sod-forming grasses, bobwhites nest in any available litter and vegetation clumps. Patches of bunchgrasses, forbs, or shrubs provide better cover than sod-grass nest sites. Nests are often located along habitat edges and fences.
Crop fields
Bobwhites sometimes nest in row crop fields, especially in regions with limited grassland habitat. Nests are situated in field edges, corners, irrigation ditches, and fencerows with sufficient ground cover. Soybeans and wheat provide better nesting habitat than dense or clean-tilled row crops.
Shrublands
In brushy habitats, bobwhite nests are placed under the canopy of low shrubs (often 1 m or less in height). In southern and coastal states, common nesting shrubs include sumacs, brambles, and saw palmettos. Dense stands of shrubs are avoided.
Forested habitats
Where available, bobwhites nest in open forests, forest openings, woodland edges, young clearcuts, and pine savannas where ground cover is developed but canopy cover is open. Nest sites often abut clumps of shrubs, vines, or briars.
Conservation Reserve Program (CRP)
CRP grasslands planted for bobwhite habitat are widely used for nesting in many regions. Native warm-season grasses provide better nesting structure than exotic cool-season grasses. Adding forbs enhances habitat quality. Patches of shrubs and brush are beneficial but high density shrub cover reduces suitability. A diversity of grass and forb heights with adequate litter enhances nest concealment. Regular disturbance (such as disking, fire, or grazing) sets back succession and maintains open cover.
Nest characteristics
Bobwhite nests are shallow scrapes or bowls built on the ground by the female. Typical features:
– Placement: Ground surface hidden under overhead vegetation
– Substrate: Hollowed out litter, dead grass, leaves, pine needles, etc.
– Dimensions: 8-12 cm across and 2.5-5 cm deep
– Lining: Lined with finer dead grasses and forbs
– Eggs: 12-14 white eggs
Nest bowl and lining materials match the surrounding vegetation. This camouflage helps conceal the nest from predators. The female sits tight on the nest with cryptic plumage that blends into the surroundings when incubating eggs.
Nest spacing
Bobwhite nests are distributed non-randomly across the landscape in suitable habitat patches. Nest density varies by habitat quality, management practices, and population density. Reported averages include:
Habitat | Nest density |
Kansas CRP, optimal cover | 1 nest per 1-3 ha |
Oklahoma rangeland, grazed | 1 nest per 2-4 ha |
Georgia pasture | 1 nest per 5-6 ha |
Florida rangeland | 1 nest per 6-7 ha |
Higher densities occur in the most favorable nesting cover. Nest abundance decreases as habitat conditions deteriorate. Healthy bobwhite populations require adequate availability of quality nesting cover distributed in patches across the landscape.
Renesting behavior
Bobwhites commonly renest following nest loss. The renesting rate depends on timing in the breeding season and population age structure. In one Florida study, 66% renested after failed first nests and 32% renested after second failures. Older females more readily renest than first-year breeders. With a long nesting season (April-September), bobwhites may raise 2-3 broods per year through renesting. Access to suitable habitat for renesting boosts productivity.
Nest success rates
Nest success averages 30-40% for bobwhites in most regions but varies from 11-80% by habitat and predator community. Documented nest success includes:
Study location | Habitat | Nest success |
Kansas | CRP grassland | 20-40% |
Texas | Coastal grassland | 27-32% |
Alabama | Pine savanna | 11-26% |
Oklahoma | Rangeland | 32-80% |
Nest success tends to be higher in undisturbed native habitats and where predator communities are balanced. Frequent disturbance and fragmentation increase nest losses. Maintaining quality nesting cover across large areas enhances nest success and recruitment.
Causes of nest failure
Destruction of nests by predators is the primary cause of nest failures for bobwhites. Documented nest predators include:
– Mesomammals: raccoons, skunks, opossums, foxes, armadillos
– Snakes: rat snakes, garter snakes
– Ground-nesting birds: crows, jays, grackles
– Small mammals: ground squirrels, marsh rice rats, deer mice
– Domestic cats
– Fire ants
Predation accounts for 80-90% of nest failures in most ecosystems. Other causes are trampling by livestock, farm machinery, and abandonment. High nest loss prompts renesting efforts.
Reducing fragmentation and improving cover at nest sites help diminish losses to predators. Control of particularly damaging nest predators like raccoons may benefit bobwhite productivity. Maintaining balance across predator communitiesoptimizes natural ecosystem function.
Management implications
To sustain northern bobwhite populations, habitat management should provide:
– Adequate acreage of suitable nesting cover on a landscape scale
– Heterogeneous habitat with adjacent nesting, brood rearing, escape, and foraging areas
– Intermediate vegetation density with openings near ground level
– Overhead concealment from residual grasses, forbs, shrubs, and litter
– Minimal disturbance during the nesting season
Habitat plans should maintain suitable cover in large blocks and avoid fragmenting the landscape with dense woody growth or barriers to movement. Disking, strip disking, prescribed fire, and grazing can create openings and set back succession in grasslands. Rotational disturbance helps ensure availability of nesting habitat each year. Providing quality nesting cover is key for quail conservation.
Conclusion
Northern bobwhites nest on the ground in relatively open habitats with adequate concealment cover. They use a variety of vegetation types for nesting across their range, adapting to local habitat composition and structure. Bobwhites often nest near edges and habitat transitions. Typical nest sites have overhead screening from grasses, forbs, shrubs or litter with open ground nearby. Nests are shallow bowls lined with dead vegetation matching the surroundings. Nest density varies with habitat quality and population density. Renesting is common after nest failure. Nest success averages 30-40% but is higher in undisturbed, contiguous habitats. Predation is the major cause of nest loss. Management for bobwhites should maintain suitable nesting cover in large blocks since habitat fragmentation increases nest losses. Providing quality nesting habitat is an essential practice for sustaining bobwhite populations.