The Wood Duck (Aix sponsa) is one of North America’s most visually striking waterfowl, recognizable by the male’s iridescent plumage and crested head. These ducks are unique cavity nesters, relying on natural tree hollows or specialized boxes for their nests, typically near water. This reliance on sheltered nest sites complicates the answer to how many eggs they lay. Understanding the true number requires separating the single female’s biological output from the collective results sometimes found in a shared nesting space.
The Standard Wood Duck Clutch
The true clutch size, representing the reproductive effort of a single female Wood Duck, is consistent and biologically determined. A typical clutch ranges from 9 to 14 eggs, with many nests averaging about 12. The female lays a single egg each day, usually in the early morning, until the clutch is complete.
The eggs are creamy white or tan and have a slightly elliptical shape. Once the eggs are laid, the hen begins incubation, ensuring the entire group hatches synchronously. This standard number reflects the maximum number of ducklings a single female can physically cover and successfully raise.
The Unique Practice of Dump Nesting
The straightforward biological count is often increased by “dump nesting,” or intraspecific brood parasitism. This practice involves one female laying her eggs in the active nest of another female of the same species. This occurs most frequently where suitable nesting sites are visible or placed close together, such as in managed nest box projects.
The result of multiple females contributing to a single nest is an inflated egg count, often reaching 20, 30, or over 40 eggs. In extreme cases, nests have been documented containing as many as 58 eggs. Females that engage in this behavior are often younger or those unable to secure their own nest site.
These super-clutches rarely lead to successful outcomes for all the eggs involved. The primary female can only effectively heat and turn the eggs she can cover, meaning eggs on the periphery often fail to develop. Overly large clutches may also cause the primary hen to abandon the nest, resulting in a very low hatch rate.
Nesting Environment and Incubation
Wood Ducks rely on pre-existing cavities in large trees, typically located over or near water. The female lines the cavity with down feathers plucked from her breast to create a soft, insulated nest. Artificial nest boxes, which mimic these natural hollows, are important tools for population management.
Once eggs are laid, the female begins incubation, which lasts approximately 28 to 37 days. During this period, the male departs and plays no further role in raising the young. The hen leaves the nest only twice daily, once in the morning and once in the evening, to feed for short periods.
After the ducklings hatch, they remain in the tree cavity for about 24 hours. The female then descends to the base of the tree and calls to the brood. Responding to her call, the ducklings use their sharp claws to climb to the entrance hole and leap to the ground, sometimes dropping from heights of 60 feet or more, before following their mother to the water.