Fire ecology in northern sedge meadows: Factors influencing yellow rails and other birds at Seney National Wildlife Refuge
The yellow rail is a focal species of concern associated with shallowly flooded emergent wetlands, most commonly sedge meadows. Yellow rail populations are believed to be limited by loss or degradation of wetland habitat due to drainage, altered hydrology, and fire suppression, factors which have resulted in encroachment of shrubs and change in vegetative cover in many sedge meadows. Fire suppression and altered hydrology often have resulted in the encroachment of tall shrubs and trees into open sedge meadow peatlands, altering vegetation structure and community composition and in turn the bird community. Seney National Wildlife Refuge, located in the upper peninsula of Michigan, has extensive sedge meadows and an active fire program, and has been the site of historic yellow rail studies. During 2007-2010, I investigated the distribution and response of yellow rails and other birds and vegetation response to spring and summer burns. The goal of this study is to improve our knowledge about the effects of prescribed burning on the distribution, abundance, and habitat use of bird species of special interest (yellow rails, Le Conte’s sparrow, and sedge wren) in sedge meadows, as related to changes in vegetation community and structure. Objectives of the study were 1) evaluate effects of prescribed burning and hydrology on plant community, cover, and structure; 2) describe occurrence and distribution of yellow rails and relate to habitat characteristics; and 3) describe occurrence and distribution of Le Conte’s sparrow, sedge wrens, and other birds and relate to habitat characteristics. Field crews conducted nocturnal surveys for yellow rails and morning surveys for other breeding birds on experimental blocks as well as in other sedge meadows in the refuge. Areas surveyed include a variety of water and shrub conditions, ranging from very open sedge meadows with greater depths of spring flooding and low shrub cover, to areas with heavy cover of speckled alder, bog birch, and tamarack and minimal spring flooding. Detailed vegetation data were collected on 8, 1-ha experimental blocks, 4 of which were burned in 2008. Results of the yellow rail component of the study have been published; analyses of vegetation data and bird community data are ongoing.