Establishing effective harvest strategies for wood ducks is challenging because the species’ population size is difficult to estimate. Because of the great decline in numbers of wood ducks in the early 20th century, and ongoing difficulty with estimating their population size, daily bag limits have been conservative. In 1941, the first year that wood ducks could be hunted legally in the United States since 1918, one or two wood ducks per hunter per day were permitted in parts of the Atlantic and Mississippi flyways. Most states, though, did not allow legal hunting of wood ducks until 1959 because of possible population declines. For the next several decades and through the present, conservative one- to two-bird bag limits have prevailed. However, in some years and states, bag limits have been more liberal, such as a legal daily limit of seven wood ducks in the Pacific Flyway during the 1975-76 hunting season.
Harvest management of wood ducks remains relatively conservative in the United States. In 1995, the U.S. Fish and Wildlife Service (USFWS) developed a waterfowl harvest management system termed Adaptive Harvest Management (AHM). AHM has several goals, but basically it seeks to provide a more systematic approach to establishing waterfowl hunting regulations. Hunting seasons of 20, 30, 45, or 60 days are established based on numbers of breeding pairs of mallards and prairie wetland ponds counted each year in May. During much of the 1990s, when breeding pairs of ducks and pothole wetlands were high, 60-day duck seasons existed from 1997-1998 to 2002-2003. That many consecutive lengthy seasons had not occurred in the two eastern flyways since the 1950s.
Biologists have been curious about how the liberal duck seasons might be affecting wood duck populations. In 2002, waterfowl researchers H.W. Heusmann and John McDonald analyzed wood duck population and harvest data from the Atlantic and Mississippi flyways. They subdivided the two flyways into six regions, based on the latitude of an individual state (i.e., Minnesota, New York, and others considered “northern,” Pennsylvania, Iowa, and others were “middle,” and North Carolina, Tennessee, Arkansas, and those farther south were “southern”). The researchers also examined numbers of hunters, wood duck harvests, and banding data. They determined that total wood duck harvests increased in both flyways during the liberal 60-day hunting seasons. Although this might have been expected, it was interesting because the increased harvest of wood ducks probably benefited southern hunters more than northern hunters. This is because northern wood ducks migrate earlier in fall than some other waterfowl species, and many wood ducks were probably present in southern states for the duration of the 60-day seasons.
The next logical question asked by Heusmann and McDonald was whether the increased harvest harmed wood duck populations. They evaluated the BBS and other breeding surveys and concluded that the long-term (1966-2000) and more short-term (1980-2000) data indicated maintenance or growth of wood duck populations in the Atlantic and Pacific flyways. Information available from the 1997-2002 liberal seasons suggests “population leveling” or even a reversal of the population trend. However, despite an apparent changing trend, there does not appear to be any indication that liberal hunting seasons have harmed wood duck populations.
Regardless of future harvest strategies, regulations will remain rather conservative because of the lack of efficient large-scale methods to assess the population status of wood ducks.
Nest Box Programs
The 1930s marked the budding of the wildlife management profession. It also was the time when Dr. Bellrose and Arthur Hawkins initiated studies of wood ducks nesting in man-made nest structures (nest boxes) at Chautauqua National Wildlife Refuge in Illinois. Since then, nest box programs have been popular among biologists and conservation-minded private citizens for studying and propagating wood ducks.
Today, it is estimated that 300,000 wood duck nest boxes produce 100,000 ducklings annually in North America. The use of nest boxes varies among regions, and basically is influenced by the availability of suitable natural tree cavities, the proximity of wetlands valuable to wood ducks, and other factors. In 1994, Dr. Bellrose estimated that states such as Iowa, Missouri, Illinois, and Ohio contain 7 percent of the wetlands important to waterfowl in the Mississippi Flyway, but only 17 percent of that land comprised hardwood forest. Alternatively, northern states such as Michigan, Minnesota, and Wisconsin contain 41 percent of important wetlands in the Mississippi Flyway, but 31 percent of that landscape is covered by forest. Thus, the use of nest boxes generally is greater in mid-latitude or southern areas because of fewer natural tree cavities.
Regardless of geographic location, nest boxes that exist among quality brood habitats and that are properly maintained can increase local wood duck populations.
Basically, wood ducks need a cavity in which to nest, and an adjacent (one to three miles) wetland habitat that contains some trees, shrubs, or dense herbaceous vegetation that provides quantities of aquatic insects for ducklings. Generally, where such a substantial food base occurs and natural tree cavities are sparse, there may be significant use of nest boxes.