Some of the most important questions that the Marsh Monitoring Program will help answer relate to what habitat types are most important for supporting amphibians and marsh birds throughout the Great Lakes basin. One way of looking at this is to ask "If we surveyed a set of new marshes using the MMP protocol, what would we expect to find?" Below are a few examples of how this approach can be applied to assessing the habitat needs of two marsh bird species, and how species habitat requirements need to be built into the bigger picture of marsh management.

Black Tern

The Black Tern population is believed to have undergone a significant continental decline since 1966 and is therefore considered a species of conservation concern in both the U.S. and Canada. Loss and degradation of wetlands used during breeding, migration and on the wintering grounds are all potential causes of Black Tern population declines.

But what is it that Black Terns really need in terms of breeding habitat? And how do these habitat requirements differ across the species' range?

Virginia Rail

Because they are so secretive, we don't yet know very much about population trends of Virginia Rails.

Managing Landscapes for Diversity

One of the challenges of wetland managers and conservationists is to encourage the development of landscapes that contain habitats appropriate for a wide range of species.

Marshes managed for Black Terns would need to be fairly large wetlands and contain significant hemi-marsh areas. Although the hemi-marsh often supports the greatest species diversity, the patterns observed in Virginia Rail presence is a good reminder that different habitat conditions are required by different species. Only when we have a full understanding of what these habitat needs and tolerances are can we effectively manage our landscapes for all marsh nesting species. We call this "holistic management."

Identifying how landscapes should be managed for wetland dependent species also requires an understanding of wetland dynamics. Wetlands are never static systems. They do change over time, primarily because of changes in water level.

In a naturally functioning system, water levels in a wetland are allowed to fluctuate, seasonally and annually. In response, the composition and density of wetland plants change through the dry and wet periods. At any one time, wetlands with different basin shapes and amounts of water input would differ in their vegetational patterns. In a well-functioning landscape, some wetlands would be in the hemi-marsh stage while others would contain higher or lower proportions of emergent vegetation and open water. Black Terns and several other species would be present in many of the larger wetlands with extensive hemi-marsh areas. Virginia Rails and some other species would occupy those areas having dense emergent vegetation.

Answering the questions necessary to manage and conserve wetlands holistically requires some thoughtful investigation. With support from Environment Canada and the U.S. Environmental Protection Agency, hundreds of MMP volunteers are building the scientific information base needed to help identify the habitat requirements of a wide range of wildlife species over a broad geographic area. Their efforts are already making an important contribution to conservation, which will increase over time.