In my experience of watching Hoodies and Woodies over the last four
years, I've found them to be equal opportunity exploiters of each
other (though the Woodies might have an advantage in this regard).
Both will lay eggs in a nest box occupied by the other species,
waiting until the hen briefly leaves during the day, then entering
the box and laying an egg. Often there are interspecies or
intraspecies fights between hens in the nest box. With incubation
times the same, the eggs hatch at the same time, and nestlings of
both species will jump out of the nest cavity together and join
whichever mother is available down on the lake. I have written about
this on Tweeters previously, if you would like to do a search.

Fawn Lake in Mason County, where I live, now has seven Wood Duck nest
boxes. Three are ones that I take care of. Currently there are two
pairs of Woodies and one pair of Hoodies actively investigating the
boxes and probably laying eggs. Yesterday I watched a female Woody
enter one box, and settle in the center of the box, rearranging wood
chips to fit her body using feet and bill. She stayed about ten
minutes--long enough to lay an eggs and bury it among the chips.

Lee Rentz, Shelton, WA
lee at leerentz.com