There is limited understanding of the influence of fire and vegetation structure on bird communities in dry oak (Quercus spp.) savannas of the Upper Midwest and whether bird communities in restored savanna habitats are similar to those in remnant savannas. During the 2001 and 2002 breeding seasons, we examined the relationship between bird communities and environmental variables, including vegetation characteristics and site prescribed-burn frequencies, across a habitat gradient in dry oak savannas in central Minnesota. The habitat gradient we studied went from: (1) prairie to (2) remnant oak savanna to (3) oak woodland undergoing savanna restoration via fire or mechanical removal of woody vegetation to (4) oak woodland. We conducted fixed-radius point counts (n = 120) within habitats with either prairie groundcover or predominately oak canopy. We described canopy and groundcover characteristics at a sub-sample (n = 28) of non-prairie points, and collected canopy and woody species richness data and prescribed-burn frequencies over the past 20 years for all points. Observed bird communities were most strongly correlated with canopy cover and burn frequency and, to a lesser extent, attributes of the shrub component. Most savanna points had bird communities that were distinct from those found at oak woodland or oak woodland points undergoing restoration via burning. Savanna points similar to oak woodland points were in areas managed by periodic cutting rather than burning. Remnant savanna bird communities were more strongly associated with prescribed burning than those in other habitat types, but it appeared that most oak woodlands that had undergone ≥ 20 years of prescribed burning remained ecologically distinct from remnant savannas. This suggests that some savannas that have converted to oak woodlands may exist in an alternative, or stable, ecological state even following extended restoration efforts.
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