Click on the images in the collage at right to see it enlarged.
David Marks is shown collecting data in
the field in the lower right. In the upper right is a map of the sites
where he collected the data for his research project. The bar graph shows
the differences in logistic regression models used to indicate which scale
is best at predicting the presence of species of Marsh Wren or Swamp Sparrows.
The best model for predicting the occurrence of the Marsh Wren is at the
25 m scale while the model combining all 3 landscape scales is the best
for the Swamp Sparrow. For both species, landscape model success increases
when the 3 scales are combined.
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 David Marks 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 including the EPA GLEI project with his advisor Dr. Robert Howe and a project investigating the effectiveness birth control measures to reduce populations Canada geese where he tracked radio collared nesting pairs near Green Bay, WI. He is also a Statistics Teaching Assistant for the Natural & Applied Sciences Dept.
His masters research involves trying to identify important ecological indicators for wetland bird species in the coastal Great Lakes wetlands. Although the relationships of birds to local habitat and larger-scale landscape variables have been the focus of many studies, surprisingly few investigations have focused on wetland systems, especially coastal wetlands. These wetlands are of particular concern because of the high degree of anthropogenic stress associated with coastal urbanization and residential development. Coastal ecosystems are highly dynamic in nature and the relationships between habitat and species distributions are often confounded by temporal change. Marks and his colleagues have studied the birds living within 63 coastal wetlands of the western Great Lakes region along Lake Michigan and Lake Huron during 2001 and 2002. Local habitat and landscape variables at these sites were quantified and associated with presence/absence of individual bird species. The local habitat variables were sampled by a relevé sampling method and landscape variables were analyzed using 7-band LandSat Thematic Mapper satellite images.
Results identify the most influential predictors for
several key species of wetland birds. For example, Marsh Wrens seem to
be making their site selections based at the local (25 m) scale, indicating
that the habitat within the wetlands is more important than the surrounding
landscape. They are most likely to be found in areas with high amounts
of cattail, water, and rushes. Swamp Sparrows seem to be making their
site selections based on the landscape scales and the larger local scale
(100 m). They are more generalist in their habitat selection within wetlands,
occupying areas with varying amounts of grass, cattails, and shrubs while
avoiding areas with high amounts of trees, bare ground, and open water.
In the poster that he is presenting at the Conservation Biology meeting
he will discuss the relative importance of using the different geographic
scales for describing the ecological condition of coastal wetland birds.
Land managers need to take this into account when designing protection
strategies for target species. Habitat at the local (<100 m) scale
might be critical for some species, while larger scale landscape features
might be important for others.
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 http://glei.nrri.umn.edu.
Funding was also provided by the Cofrin Center for Biodiversity through and endowment and contributions of the Cofrin family.
David Marks thanks David Bartholmai and the Wisconsin Breeding Bird Atlas for the photo of the Marsh Wren.
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