Here is some wonderful information about Wood Ducks from the NC Wildlife Website:

Beginning in the late 1800’s, wood duck populations plummeted due to over harvest, deforestation, and loss of wetland habitats. Many ornithologists believed the wood duck might go extinct by the early 20th century. In 1918, the Migratory Bird Treaty Act protected the wood duck from legal harvest in the United States and Canada. Since that time, the use of artificial nesting boxes, expanding beaver popula- tions, which create some of its favored wetland habitat, and restrictive harvests have contributed significantly to its remarkable comeback. Today, wood duck populations are stable throughout its range, despite continued losses of wetland habitat.

https://www.ncwildlife.org/Portals/0/Learning/documents/Profiles/Birds/Wood_Duck_Update_2018.pdf