M.S. in Conservation Biology and Sustainable Development, December 1998
The Wisconsin Small Mammal Survey:
a volunteer-based small mammal survey program for native grassland preserves in southern Wisconsin
The Wisconsin Small Mammal Survey (WSMS) represents
a primarily volunteer-based approach to small mammal inventory work that
has evolved through an ongoing collaboration between The Nature Conservancy
(TNC), Wisconsin Department of Natural Resources (DNR), United States Fish
and Wildlife Service (USFWS) and University of Wisconsin (UW). The primary
focus of this project was to establish a base-line inventory program for
grassland-associated small mammals in Southern Wisconsin and to assess
the habitat requirements and conservation status of species considered
of Special Concern in Wisconsin. Between 1995 and 1997, more than 100 volunteers
actively participated in 31 surveys conducted at 15 sites throughout Southern
Wisconsin. Volunteers took part in all aspects of fieldwork and proved
to be a crucial resource in implementing this survey program. To prepare
volunteers for survey work, training workshops were held before the start
of each field session in (a) small mammal identification skills and (b)
animal handling and trapping techniques.
Trapping efforts were carried out twice at each site to assess seasonal differences in small mammal abundance and species richness. The effects of fire-induced changes in habitat on small mammal abundance within dry and wet community types were also assessed. Lastly, the capture efficacy of three different types of trap were compared in order to provide guidelines for future survey efforts.
Five species of conservation interest were trapped in field surveys in Wisconsin: the pygmy shrew Sorex hoyi, arctic shrew Sorex arcticus, prairie vole Microtus ochrogaster, western harvest mouse Reithrodontomys megalotis and Franklin's ground squirrel Spermophilus franklinii. Of these species, M. ochrogaster and R. megalotis were captured only in dry upland sites, whereas S. hoyi was trapped only in wet, lowland habitat in the south-eastern portion of the state.
Data from this project and a companion study conducted by the Wisconsin DNR in the central sands are (R. Bautz, pers. comm.) are in the process of being combined with museum and other records to create a small mammal atlas database for Wisconsin (E. Spencer, Wisconsin Natural Heritage Program). At the inception of this project, the rarity of all eight small mammal species of Special Concern was ranked as unknown, requiring more information to determine whether they were imperiled in the state. In the light of findings from this study and other information compiled by the Natural Heritage program, the status of all eight species remains as Special Concern.
Despite the small size and isolation of many of the preserves included in this study, many sites appeared to be exceptionally species rich and capable of supporting at least one or more species of conservation concern. Differences in species composition and relative abundance between dry and wet community types highlight the importance of preserving a diversity of habitats. In addition, significant increases in small mammal abundance and changes in species composition between consecutive trapping sessions illustrates the importance of trapping more than once at a given site. Results from this study not only underline the importance of small grassland preserves to Wisconsin small mammals, but also illustrate the vast contribution that volunteers can make to practical inventory efforts.