Grassland Bird Habitat and Ecology
Grassland birds thrive on large, open, previously-agricultural grasslands as these habitats provide the wide open treeless spaces they need to nest and reproduce. Providing the correct mix of grass height, plant species, and thatch depth is a bit of a balancing act. Whereas upland sandpipers require very short grasses, Henslow's sparrows require taller vegetation with a mix of forbs. Bobolinks and savannah sparrows, two fairly common grassland birds, have less stringent habitat requirements. For this reason, grasslands are typically managed on a three-year mowing rotation which provides a variety of grass heights and composition, as seen in the Livingston County photo at right.
Although trees and shrubs benefit wildlife in other habitats, they generally decrease nesting opportunity and productivity in grasslands, especially when forming thickets or hedgerows. In addition, many of the woody plants that colonize grasslands are aggressive invasive species, such as European buckthorn, multiflora rose, Russian olive, and black locust. Removal or thinning of hedgerows is one of the best actions a landowner can take to improve conditions for grassland birds. By removing hedgerows, like the one seen below, landowners can dramatically increase the size of the grasslands.
Thatch, the litter left over after grasses have been mowed, is used by grassland birds to build their nests. Three or four inches are ideal.Thatch also provides cover for voles and moles and is thus beneficial for grassland raptors, such as the state-endangered short-eared owl and the state-threatened northern harrier, which survive the winter by preying on these small mammals. Thatch returns nutrients to the soil, but excessive amounts of thatch can smother the growth of new grasses.
Invasive species can present a management challenge in grasslands. Ample light and productive soils provide good growing conditions for pioneer species. For example, in Jefferson County, a Landowner Incentive Program grant recipient is waging an annual battle with pale-swallowwort, a highly-invasive plant native to Europe. Carefully-timed mowing and herbicidal use have reduced the height and reproductive potential of this plant. After several years of management, grasses have begun competing with and shading this invasive plant.
Although it does not nest in grasses, the American kestrel, our smallest falcon, forages for insects and small rodents in grasslands and nests in cavities in dead and dying trees often found on the edges of grasslands. Since 2011, DEC has been working with landowners, the Peregrine Fund's American Kestrel Partnership, and the Capital District chapter of the National Audubon Society to build, install, and monitor nest boxes for American kestrels. You can learn more about kestrels and the American Kestrel Partnership, including how to build, install, and monitor your own kestrel box, on our website. You can find recommendations for managing grassland habitat on the "Best Management Practices for Grassland Birds" page.