Least Bittern

Species Name: Ixobrychus exilis


Species Distribution in Massachusetts


Federal Rank: None

Massachusetts State Rank: Endangered

Habitat Description

Feshwater and brackish marshes where tall, dense vegetation grows, generally found in marshes of over 12.5 acres. They nest in dense vegetation close to water, normally alone but occasionally in loose colonies. In Massachusetts, Least Bitterns are often found at Plum Island and along the Sudbury River.

Threats to Survival

The introduction of invasive species such as Purple Loosestrife and the common reed that alter and degrade habitat are threats to the Least Bittern. Siltation due to erosion, insecticides and chemical pollution runoff, and wakes from boats or jet skis also threaten food sources and nesting areas for the Least Bittern.

Actions Recommended to Ensure Survival

Habitat management is critical for the survival of the Least Bittern. Wetlands that are managed for the Least Bittern should be large enough to provide a range of areas which are suitable for the Least Bittern in case of natural or invasive alterations of sediment, structure, or water levels. Changes in population status should also be monitored using Least Bittern playback calls to gather information on the population and to inspect habitat characteristics.