Response of breeding birds to shearing and burning in wetland brush ecosystems

Abstract

In the absence of wildfire, emergent wetlands in the American Midwest often succeed to a shrub/scrub wetland type. Management activities, including shearing and burning are typically used to remove shrub, resulting in a more open emergent wetland condition. We surveyed breeding birds in managed and unmanaged shrub/scrub wetlands in northeast Minnesota, USA, in 1996 and 1997 to examine breeding bird response to management type (burning and shearing) and time elapsed since management. In a comparison of 58 managed sites and 58 unmanaged sites in 1996, unmanaged sites had more (P<0.05) species and individuals than managed sites. In addition, 12 of 20, individual species tested differed significantly (P<0.05) in abundance between the groups. Species associated with emergent wetland type, like the Sedge Wren (Cistothorus platensis) and LeConte’s Sparrow (Ammodramus leconteii) were more, abundant (P<0.05) in managed sites, and species that require shrubs, such as the Alder Flycatcher (Empidonax alnorum) and Golden-winged Warbler (Vermivora chrysoptera) were more abundant (P<0.05) in unmanaged sites. Examination of the effects of management type on breeding birds by either burning, shearing, or, both treatments on sites surveyed in 1997 revealed results similar to comparisons of managed and unmanaged sites completed in 1996. In addition, breeding bird composition, was not different on sites that varied in time elapsed since management. In these latter comparisons, breeding bird species and community composition were similar among all managed sites but differed from the unmanaged sites.