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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
(608) 231-9544 TTY/TDD

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Forest Disturbance Processes

Effects of savanna and woodland restoration on bats and birds in the central hardwood region

[photo:] A managed savanna site in the Missouri Ozarks

Research Issue

Savanna and woodland habitats historically covered a large portion of the Midwest and were the dominant habitats in the Ozark Plateau in the early 1800s.  Before European settlement, oak savanna covered 11-13 million hectares in the Midwest from Texas to Michigan but only 2,607 hectares remained in 1985.  Agricultural plowing, fire suppression and forest succession eliminated most oak savannas.  Fire historically maintained these open habitats by thinning the understory, reducing woody vegetation, and creating large openings in the canopy for sunlight to reach the ground.  This increased sunlight encourages floristic diversity with a dense ground flora consisting of grasses, sedges, and other composites.  Current efforts to restore savannas and woodlands use prescribed fire as the main management tool although managers often use additional mechanical treatments consisting of selective tree removal to reduce tree density.  There is great interest in restoring savanna and woodlands because of their former abundance on the landscape and high floristic diversity.  However, there is not good knowledge of the effects of restoration on wildlife or of potential conflicts with management for forest species of conservation concern.

Our Research

We are determining the effects of savanna and woodland restoration and management on migrant and resident birds and bats through several studies.  The general approach is to contrast use by birds or bats of savanna and woodland sites that have been restored and are actively managed with prescribed fire to those with no recent management and that have succeeded to more closed canopy forest. These studies include:  1) An exploratory study of bird abundance on sites in Missouri, Arkansas and Tennessee;  2) An intensive study of breeding and wintering bird density and vegetation structure in managed and non-managed savannas and woodlands in the Missouri Ozarks; 3) Reproductive success of songbirds in managed savannas and woodlands in Missouri; 4) Abundance and resource selection by brown-headed nuthatches (Sitta pusilla) in pine savannas and woodlands in Arkansas; and 5) Site occupancy by bats and effects of vegetation structure in the Missouri Ozarks.   

Research Results

[image:] Some species, such as the Summer Tanager (left), were more abundant in managed savannas and woodlands, whereas other species, such as the Acadian flycatcher (right), were more abundant on non-managed sites that had succeeded to closed canopy forest.

In our exploratory study across Missouri, Arkansas, and Tennessee, we conducted 260 bird surveys at managed sites and 244 at control sites.  Blue-winged warbler, Eastern towhee , Eastern wood-pewee, field sparrow, prairie warbler, and summer tanager were more abundant in managed sites; whereas Acadian flycatcher and worm-eating warbler were more abundant in non-managed sites.  Abundance of blue-winged warbler, field sparrow, and prairie warbler decreased with canopy cover while Eastern towhee and summer tanager reached their greatest abundance in intermediate canopy cover.  Eastern wood-pewee and prairie warbler were the most abundant breeding birds with 0.22 and 0.15 singing males/ha, respectively.  Savannas and woodlands provide habitat for a diverse mix of grassland-shrub and canopy nesting birds that are of high conservation concern.  Work on the other studies is ongoing.

Research Participants

Principal Investigators

  • Sybill Amelon, US Forest Service- Northern Research Station Research Wildlife Biologist
  • Frank R Thompson III, US Forest Service- Northern Research Station Research Wildlife Biologist

Research Partners

Last Modified: 03/01/2012