Date of this Version
Fire Science Brief, Issue 9, June 2008
Roughly 25,000 acres of grassland in the National Wildlife Refuges of North Dakota and eastern Montana are treated every year with prescribed fi re, mostly on northern mixed-grass prairie. Although this shrinking ecosystem is fi readapted, there have been very few studies of the effects of prescribed fi re on wildlife, introduced and native plants, and wildlife-habitat relationships in this delicate ecosystem. For this project, researchers documented short- and long-term fi re effects on abundance, productivity, nest site selection and nest predation in migratory birds, especially grassland songbirds. They also measured the impacts of encroaching woody shrubs and trees on breeding populations of common bird species and the manner in which the historic fi re regime has shaped the type, distribution and structure of vegetation. Results indicate that native bird species are generally well adapted to frequent fi res. Any loss of breeding habitat in the fi rst post-fi re season is more than made up for by the subsequent renewal of grasses and reduction in fuel loads. Nest predation appears to be short term. Lack of periodic disturbance by fi re and grazing has allowed encroachment by trees, tall shrubs and invasive grasses, negatively impacting songbird breeding success and survival of native grasses. Informed use of prescribed fi re enhances nesting success and abundance of grassland birds, sustains the native vegetation they require, and is essential for perpetuation of threatened northern mixed-grass prairie landscapes.