Avian Use of Vertical Strata and Plantings in Farmstead Shelterbelts

Abstract

Use of 3 vertical strata and 13 genera of trees and shrubs by 28 bird species was examined during a 2-year study of 7 farmstead shelterbelts in Dakota County, Minnesota. Similar use of strata occasionally occurred between bird species, but similarities in use of plantings were not found. The majority (60.7%) of the bird species was most often sighted in the ground stratum. Genera of plantings preferred by the avian community included Picea, Populus, Acer, Lonicera, and Ulmus. Bird species best adapted to shelterbelts appeared to be generalists in strata and planting use. Inclusion of the 5 preferred genera of trees and shrubs in new shelterbelts or in old shelterbelts in need of renovation would benefit a variety of bird species in intensively farmed regions. This management practice would increase vegetative complexity in a vertical dimension, enabling coexisting bird species to partition space more effectively in these spatially restricted habitats. J. WILDL. MANAGE. 46(1):50-60 Farmstead shelterbelts are planted primarily to provide year-round protection to humans, domestic animals, homes, and buildings from the effects of high winds, windchills, and snowdrifts, thereby reducing costs of fuel, feed, maintenance, and labor associated with farm operations (Smith and Scholten 1980). These manmade habitats are also important to many bird species that depend on woody habitats as sources of food and cover in intensively farmed regions (Orendurff 1941, Martin 1978). As a consequence of larger farms, increased mechanization, planting of extensive fields in fewer types of crops (principally corn and soybeans), and other recent agricultural trends, farmstead shelterbelts and other wooded habitats often comprise only 3% or less of the total area (Griffith 1976). Moreover, farmstead shelterbelts are generally less than 1 ha in size, and vegetative composition may vary considerably among shelterbelts because landowners can select from a variety of d ciduous and coniferous trees and shrubs when planting new or renovating existing shelterbelts (Smith and Scholten 1980). Thus, an understanding of the m nner by which avian species exploit space in these spatially restricted, manmade habitats is essential for the proper management of birds in the Great Plains