Seeking location(s) of Natural Cavity Nesting Sites for Wood Ducks

Hello,  I've been asked to post the message below.
Barbara Duerksen

Richland County

Laura and Neil Rettig are working on a 3 hour film for Nat Geo about the
animals and birds of the Mississippi River, and are hoping to film wood duck
babies this spring. They are hoping to locate natural cavities that are
being used by wood ducks in southwestern Wisconsin.  

Please contact nrettig@mwt.net