Article, maps and image by Jim Woodford | RGS & AWS Forest Habitat Biologist – Wisconsin
In Wisconsin, ruffed grouse are distributed nearly statewide with highest densities found in the northern half of the state. In many areas, grouse abundance has been declining with observations in the southeastern part of the state considered uncommon. American woodcock are seasonal visitors to Wisconsin. They return in early spring, mate, lay eggs and raise young through the summer and migrate south in the fall. Statewide surveys for mating males in the spring have shown declines for both species that follow the same overall negative trend across acres of zero to 20-year-old forested lands in the state.
There are lands in Wisconsin where management has focused on creating and maintaining suitable habitat for ruffed grouse and woodcock, commonly called Ruffed Grouse Management Areas. These areas are located throughout the northern and central parts of the state on public lands, including county, state and federally managed lands with a few also on privately owned lands. Generally, foresters, biologists and hunters in Wisconsin assume these areas with management goals focused on promoting suitable habitat for grouse and woodcock contain the best habitat for these species. We set out to test this assumption by mapping these areas, inventorying the landcover and evaluating existing habitat conditions.
We found documentation that included web maps, property planning maps and scientific reports of public lands focusing on ruffed grouse and woodcock management in Wisconsin starting in the early 1960s and continuing to present day. So far, we have located and mapped 54 different areas covering over 220,000 acres on state lands. These properties range in size from 581 to 25,500 acres, and have been both formally and informally adopted or physically signed under various names, but usually are termed Ruffed Grouse Management Areas (RGMAs). Habitat management responsibilities for these properties varies with the ownership agency leading efforts in cooperation with partners including RGS & AWS.
To evaluate conditions, a habitat quality index was developed using forest stand metrics, including land cover type, forest stand age and size and patch interspersion at a 40-acre patch scale. Most of the metrics used were provided in forest and non-forest stand inventory data sets from the Wisconsin Department of Natural Resources (WDNR) for state and county lands and from the Chequamegon-Nicolet National Forest for federal lands. We used the forest and non-forest inventory datasets and assigned each patch a habitat landcover type and age that represented suitable habitat for grouse and woodcock. We used the following age classes: 0- to 5-year-old, 6- to 15-year-old, 16- to 25-year-old, 26- to 45-year-old, 45+-year-old and no age. Examples of no age habitat were mixed age forest types, grasslands and wetland shrubs. This then became the suitable habitat dataset that was the basis for creating the habitat quality index.
Patch interspersion is a somewhat complicated metric to quantify, but is an extremely important habitat metric to include in this type of evaluation. One way to think about patch interspersion is to consider it the nexus where multiple suitable habitat types or ages meet within an area or, more simply put, the center of a bicycle wheel where each spoke is a different suitable habitat type or age. To complete the analysis, we used the software program ArcMap® with a spatial analyst extension. This program works with files called shapefiles that are a combination of geospatial maps and databases. Shapefiles are the same “smart” maps used by commercial phone mapping applications like Onyx® and Avenza®.
Landcover across the RGMAs varied widely with aspen forest types covering 11% to 89% of individual properties. Upland brush and wetland shrublands covered 0% to 8% and permanent grasslands covered 0% to 2.3% of the RGMAs. To calculate the habitat quality index for each individual RGMA, all 40-acre patches within the boundary were summarized to calculate an overall habitat quality index. The habitat quality index we created can have a property summary score that ranges from a minimum of 0.0 to a maximum of 2.0. The RGMAs we scored ranged from a low of 0.42 to a high of 1.53.
So, what can you infer from this type of habitat quality index score? First, our project objectively evaluated habitat conditions across all known RGMAs on public lands in the state, which allows meaningful comparisons both within and between properties. Second, by design, the higher a property’s habitat quality index score is, the greater the habitat diversity and habitat quality for these bird species. Properties with scores greater than 1.0 appear in good shape while scores less than 1.0 could benefit from additional management concentration on stand size (look to reduce forest stands to under 25 acres) and stand age diversity (aim to establish regeneration practices on adjacent stands at least eight to 10 years apart). Third, as no RGMA score reached the maximum, there appears to be room for habitat improvement on all properties. To improve quality, we should review each stand type and age, compare these to adjacent stands and, finally, review those found throughout the property.
Being able to connect a property’s habitat index score to grouse, woodcock and other early successional bird numbers was not one of our project’s original goals. However, as we have rolled these results out to public land managers, it soon became a common request. Thus, in spring 2024, we began bird surveys for a group of RGMAs to make this additional comparison possible.
Work on this project was completed through a formal partnership between Wisconsin Department of Natural Resources and RGS & AWS. There are likely a few more RGMAs to find and map, and we’ll continue searching. In addition, public land agencies likely will look to focus their management on early successional forests and vegetation in new areas, so new RGMAs will undoubtedly be created in the future.
Jim Woodford is a forest habitat biologist for RGS & AWS located in Rhinelander, Wisconsin. He came to RGS & AWS after retiring from the Wisconsin Department of Natural Resources after a 27-year career as a conservation biologist. He resides in the Rhinelander area with his wife and German shorthaired pointer.
