SIU graduate student John Denton completes measurements of a tree cavity potentially suitable for nesting wood ducks and hooded mergansers. FWS photo by Greg Soulliere

Staff from the Upper Mississippi River and Great Lakes Region Joint Venture (JV) are working with partners from Southern Illinois University (SIU) and Refuges to test the assumption that cavity-nesting ducks (wood ducks, hooded mergansers, and common goldeneyes) are not limited by nest sites in the region. 

For over 70 years, the practice of placing artificial nest sites for these duck species has been a standard management technique to increase populations.  However, scientists working with the JV have questioned the importance of next boxes for ducks considering the expansion and maturation of forest (and likely production of natural tree cavities).  The loss of quality brood-rearing wetlands is probably a higher habitat conservation priority, but information is lacking to make informed management decisions.

The nest-cavity research project is being funded by the JV, and JV Staff are also assisting with field work.  Four study sites will be surveyed during the next two years, including three FWS refuges (Muskatatuck, Shiawassee, and Mingo) and a large state area in central Wisconsin (Mead Wildlife Area). 

Duck nest cavities were examined at these locations 20-40 years ago, making them excellent sites to revisit and determine change in cavity density.  In addition to climbing trees and measuring tree cavity dimensions and suitability for nesting, information is also being collected from smaller (non-cavity) trees on sample plots. 

Using information collected by field crews, forest inventory data from the U.S. Forest Service, and duck habitat models developed by FWS staff, the abundance and distribution of potential breeding habitat for cavity-nesting ducks will be predicted decades into the future, providing a valuable tool for conservation planning in Region 3.