Nests are hard to find , located in dense, tall vegetation. Greenwings prefer very shallow water or exposed mud flats to feed on seeds or mollusks. I am not aware of how to seperate them, and these are not distinguished in hunting regs. Bluewings concentrate their breeding range in US and Canadian prairie pothole region. We are on the very edge of their breeding range and a few broods have been counted in Maine.
Bluewings have very complex southward fall migration.
Some actually fly north before flying south. 50,000 or so migrate through New England. These migrate early, before the duck season opens, so only a few hundred harvested in Maine. Most however winter in Mexico and South America. Make very long non-stop flights over ocean.