Natural history notes on wood ducks
Wood duck houses also are an important rite of spring across the country, and Outdoor News readers look forward to the annual Wood Duck Challenge each March.
What follows are some important facts about wood ducks to accompany the graphical feature shown on the right.
Wood ducks are half the size of mallards. They are uniquely equipped to fly through a tangle of branches to reach their nest site in a tree cavity: They have the largest eyes of any duck, a broad wing for maneuvering, aided by a tail that is long and wide. They also are the “track stars” of the duck world, with legs near the center of their body. This helps when searching the forest floor for acorns.
Woodies are classed as perching ducks for good reason
Their highly developed hind toes and claws allow them to grasp and perch on branches. They mainly dabble and tip for food, but I’ve watched them dive for acorns that had fallen in a lake from an overhanging oak branch.
The wood duck occurs naturally only in North America. See its specific range in graphic at left.
Again, the wood duck is unique. Frank Bellrose, who spent his professional life researching wood ducks, has estimated that overall, only about two-thirds of woodies migrate to and from northern breeding grounds.
Folks living south of North Carolina, Tennessee, and the middle of Arkansas often refer to woodies as summer ducks, since their local hens stick around to lay their eggs at home. Migratory woodies need open water with aquatic invertebrates as they head north. So, as days lengthen, they follow the receding ice line until they arrive at their traditional natal ponds.
Nesting behavior (as related to recovery from their low population levels in the early 20th Century)
Habitat destruction and unregulated hunting coincided with European settlement of North America. By the time hunting restrictions were enacted in the early 1900s, wood duck populations had fallen to dangerously low levels. With statutory protection in place, their unusual ability to propagate and adapt allowed woodies to make a remarkable recovery. Examples:
- Wood ducks will use and nest near a wider range of wetlands than any other duck species, including irrigation ditches and wastewater lagoons.
- They are the only North American waterfowl species to regularly raise two broods a year (in the southern portion of their large breeding range, which includes the Gulf states and California).
- A single hen lays an average of 12 eggs, one egg a day. However, clutch size is often even larger, due to the fact that a huge percentage of clutches in natural cavities and boxes are compound (laid by more than one hen but incubated by one). This is normal wood duck nesting behavior, and overall is a positive factor in production. Hatches of 17 to 20-plus ducklings are common in established units.
- Philopatry is the instinct that drives a hen to home back to a natural cavity or box used in a previous season – or drives a juvenile hen to return to where she was hatched. Incubating woodie hens, banded in a box, have been documented using the same box successfully for nine years in a row.
- Among duck species that nest in tree cavities, the woodie has been the most successful in adapting to artificial nest boxes, and this has helped them recover. Further, boxes easily can be made safe from mammalian predators by mounting them on poles with predator guards – in contrast to nests in natural cavities or boxes on trees. (See Outdoor News – Wood Duck Challenge)
Incubation, hatch, and jump: Full-time incubation averages 30 days. In-box cameras with microphones have allowed the hens to teach observers many things:
- Hens begin talking to their clutch even before the ducklings begin to carve their “exit trapdoor” (cap) in the fat end of the egg.
- Hens take two breaks a day – morning and evening – to eat and drink.
- Once hatching begins, the hen becomes a cheerleader, chattering at the eggs. The ducklings must get out of the egg by themselves.
- Hatching of a clutch is usually complete in less than six hours. The ducklings will jump the next day. They are not fed in the box.
- The drake plays no part in the jump or brood rearing.
Aquatic invertebrates have been shown to make up 75 percent of a duckling’s diet during the first two weeks of life. Tight attachment to the hen begins to loosen at about three weeks. Ducklings start their own self-taught flight school when they’re about 60 days old.
In early autumn, wood ducks from nearby locales begin gathering and staging in traditional roost sites at night. Wood ducks pair up early, and courting behavior may begin in the roosts prior to migration.
Hunting and harvest
Because of the wood duck’s secretive nesting habitat, biologists understand that it is difficult to accurately estimate wood duck numbers by flying transects and conducting ground counts. Therefore, it has been the tradition to be extra conservative when setting daily harvest limits. The Wood Duck Society supports that tradition. It remains to be seen whether the now-universal adoption of a three-bird daily limit will negatively affect the population of breeding hens. As fellow duck hunters, we suggest that choosing the drake should always be the unwritten rule for conservationists when hunting wood ducks.
Wood Duck Society
For more information, visit The Wood Duck Society’s website.