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Click on the images in the collage at right to see enlargements.


D. Marks research .

The bar graph shows the differences in logistic regression models used to indicate which scale is best at predicting the presence of 3 species of anurans (frogs) at different scales (distances in the landscape) and among landscape types. The graph shows the statistical fit of the logitic modelat different landscape scales (distances).

map of sampling locations. graph of relative success of models of habitat predictors. gray tree frog. Spring peeper. Green frog.

UW Green Bay graduate students Julie Gibson, Brad Herrick, David Marks, and Steve Price presented the results of their masters thesis research at the Society for Conservation Biology Meeting being held in Duluth, MN this week. Each week in July we will feature the research of these students who have worked for and done research at the Cofrin Center for Biodiversity. Their research has been supported by a donations by the Cofrin family and helps us preserve the biodiversity of birds, wetlands, and amphibians in the Northern Great Lakes region.

This week we feature the research of Steve Price who received his undergraduate degree in Environmental Science at UW Green Bay and and is now completing a masters degree in Environmental Science and Policy with an emphasis in Ecosystem Studies this summer. He has worked on a number of research projects involving amphibians including the EPA GLEI project with his advisor Dr. Robert Howe. His research on four- toed salamanders (Hemidactylium scutatum) has resulted in publications in Herpetological Review.

Price's research quantified the effects of habitat composition and scale on the distribution of anuran species in 63 coastal wetlands of the western Great Lakes region. Amphibians have been widely employed as indicators of habitat quality, however the local distribution of amphibians is greatly influenced by habitat factors. Amphibian habitat can be measured at different scales of space and time creating fundamental challenges for identifying critical habitat factors. However, although the coastal Great Lakes coastal environment is an important habitat for amphibians, few studies have focused on amphibian-habitat relationships in coastal areas.

Anuran-calling surveys and habitat variables were collected at both local and landscape scales during 2002 and 2003. Stepwise logistic regression was used to create models for spring peepers (Pseudacris crucifer), eastern gray treefrogs (Hyla versicolor) and green frogs (Rana clamitans ) at each scale. Results from the logistic regression and a statistical comparison of the models (McFaddens’s R2) emphasize that habitat predictors for anurans depend on scale and differ between species. Green frogs, gray treefrogs and spring peepers are influenced by a wide variety of cover types at multiple scales in coastal areas. All species seem to be influenced primarily by vegetation cover types at larger landscape scales. Green frog occupancy seems to be related to factors acting at large spatial scales (3 km), while spring peeper occupancy is influenced by the relative amount of urban, treed, and agricultural areas within 500 m of a wetland. Gray treefrog occupancy seems to be positively associated the relative area of forest within 500 and 1000 m and negatively influenced by anthropogenic cover types (urban and agricultural) at the 3000 m scale. All species display a negative association with anthropogenic habitat cover types, such as lawn, urban areas and fragmented habitats. Since anurans are influenced by habitat cover types at different scales surrounding coastal wetlands, different species may be useful biological indicators for different stressors in the environment.

This study was funded as part of the Great Lakes Environmental Indicators (GLEI) project, directed by scientists at the Natural Resources Research Institute at the University of Minnesota Duluth. The GLEI project is a cooperative effort among scientists from eight universities around the Great Lakes, Minnesota Sea Grant, and the US EPA's Mid-Continent Ecology Division in Duluth, Minnesota, and Grosse Ile, Michigan. For more information about the GLEI project, refer to the website available at

Funding was also provided by the Cofrin Center for Biodiversity through and endowment and contributions of the Cofrin family.

Amphibian publications by S. Price

Price, S. J. 2003. Sea Turtles. Encyclopedia of World Environmental History. Berkshire Publishing Group, New Barrington, MA..

Price, S. J. and J. M. Jaskula. 2002. Hemidactylium scutatum. Record Size. Herpetological Review. 33(4):298.

Price, S. J. 2000. Geographic Distribution. Hemidactylium scutatum. Herpetological Review. 31(4):249.

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Last updated on May 9, 2014