Nature Lab

Wetland Management

Deciphering the Habitat Needs of Secretive Marsh Birds

Because they lurk deep in the weeds and reeds of wetlands, bitterns and rails are difficult to spot and study — hence they are called “secretive marsh birds” (SMBs). In the Mississippi Flyway, where many SMBs are species of conservation concern, an interagency group of Canadian and U.S. biologists (including MDC staff and others from Missouri) is working on how to best conserve them.

To assess how SMBs use habitat throughout the flyway, this group collaborated with University of Missouri researchers on a meta-analysis. “A meta-analysis,” explains postdoctoral researcher Kristen Malone, “combines results from other studies to generate broader results.” Malone read more than 1,000 studies on SMBs to find data for this analysis.

SMBs breed, migrate, and winter in different portions of the flyway. Thus, this flyway-scale study is important, says U.S. Geological Survey researcher Lisa Webb, “so that wetland management can be better coordinated throughout the flyway as opposed to being done on a state-by-state basis.”

Study results indicate that SMBs need wetlands that have “robust, emergent vegetation” — plants like cattails and bulrushes — and they are more likely to be found in wetlands that have other wetlands nearby. Wetlands in urban areas harbor fewer SMBs. Malone explains that the study also “highlighted gaps in our knowledge about these species. The biggest gap is lack of information during the nonbreeding season.” Filling this gap would enhance conservation of SMBs throughout their lifecycle.

Webb says a second phase of the project is now underway “to understand how wetland management practices can influence habitat for marsh birds. Results from the study can help identify areas where tweaks in management practices could improve conditions for marsh birds.”

Marsh Bird Habitat Study at a Glance

People:

Mississippi Flyway’s Nongame Bird Technical Section (biologists from 14 states and three Canadian provinces) and University of Missouri researchers

Study species:

• American bittern
• least bittern
• sora
• Virginia rail
• king rail
• yellow rail

Numbers show studies per state or province with data used in the meta-analysis of marsh bird habitat in the Mississippi Flyway. 85% of the studies took place during the breeding season, 15% during migration, and none during winter.

The complete study is published in Avian Conservation and Ecology, Vol. 16 (2), Article 12. doi.org/10.5751/ACE-01924-160212