EFFECTS OF MOWING AND BURNING ON SHRUBLAND AND GRASSLAND BIRDS ON NANTUCKET ISLAND, MASSACHUSETTS

Throughout the United States, declines in breeding populations of grassland and shrubland birds have prompted conservation agencies and organizations to manage and restore early-successional habitats. These habitats support a variety of birds, some of which have been classified as generalists; thus, often these birds are thought to be less affected by habitat manipulation. More information, however, is needed on the response of early-successional generalists to habitat management, because conservation agencies are increasing their focus on the regional preservation and management of common species. On Nantucket Island, Massachusetts, the goal of the Partnership for Harrier Habitat Preservation (PHHP) has been to restore more than 373 ha of grassland for the island's population of Northern Harriers (Circus cyaneus). This management program has entailed methods such as prescribed burning and mowing (e.g., brushcutting) to restore and maintain grassland habitat. Over a 3-year period, we found that songbird response to burning and mowing varied among species, depending on subtle habitat preferences and the intensity and type of management. In shrublands, Eastern Towhee (Pipilo erythrophthalmus) and Common Yellowthroat (Geothlypis trichas) abundance declined in mowed areas but were unaffected by prescribed burning. In grasslands, Savannah Sparrow (Passerculus sandwichensis) abundance showed no response to either burning or mowing, whereas Song Sparrows (Melospiza melodia) preferred unmanaged grasslands. In shrublands, mowing was the most effective method for restoring grassland habitat, whereas prescribed burning had little effect on abundances of shrubland birds and vegetation structure. In grasslands, both mowing and burning were successful in restricting shrubland encroachment and maintaining grassland habitat.