The hen is solely responsible for incubating the eggs, a process that takes around 25 to 30 days. During this time, the nest may appear unattended, leading people to question if the duck has abandoned her clutch. Ducks do leave their eggs, but this behavior is a temporary absence necessary for the hen’s survival. These brief breaks are a natural part of the reproductive cycle and do not signal permanent desertion.
Temporary Absence Versus Permanent Abandonment
A temporary absence, known as an incubation recess, is characterized by a short duration and specific protective behaviors. The hen leaves the nest to feed, drink, and preen, activities necessary to maintain her body condition. These recesses occur one to three times daily, lasting between one and three hours.
A key sign that the hen plans to return is if the eggs are carefully covered with a layer of down and nesting material. This material, which the female plucks from her breast, insulates the clutch and helps conceal it from predators. True abandonment, conversely, is marked by a prolonged, unexplained absence of 24 hours or more, particularly if the eggs feel cold and are uncovered.
The probability of a hen permanently leaving a nest is not constant throughout the cycle. Abandonment is more likely during the egg-laying phase and the first week of incubation. Once incubation is underway, the hen has invested more energy into the clutch, making her less likely to abandon it unless a severe disturbance occurs.
The Physiology of Intermittent Incubation
The survival of duck embryos during the hen’s breaks is possible due to the resilience of the egg structure and the embryo’s ability to slow its development. The thick shell and the insulating down material help retain the heat transferred from the hen’s brood patch. This insulation prevents the internal temperature from dropping too quickly or too low.
When the egg temperature decreases, the metabolic rate of the developing embryo slows down, entering a state similar to developmental arrest. This mechanism allows the embryo to tolerate temporary periods of cooling without dying. Older embryos, those in the late stage of incubation (around 20 days or more), are robust and can sometimes survive for several days without parental incubation, although their development rate is reduced.
Primary Triggers for Nest Abandonment
Permanent nest abandonment is a response to a perceived threat that outweighs the hen’s investment in the clutch. High levels of human interference or repeated disturbance can cause a hen to abandon her eggs, especially if she is repeatedly flushed from the nest. When the hen is forced off, the likelihood of the eggs being discovered by a predator increases, posing a greater risk.
Predation events are another major trigger, particularly if a predator partially destroys the clutch. The hen may abandon the remaining eggs if she perceives the nest site to be too dangerous. Environmental factors also contribute to abandonment, such as flooding or extreme weather that damages the nest structure.
The decision to abandon is tied to the timing within the nesting season and the hen’s reproductive future. A hen is more likely to abandon an early clutch because she retains the energy and time to attempt a second, or “renest,” later in the season. As the reproductive window narrows, the hen’s commitment to the existing clutch increases.
Dealing With an Unattended Nest
The most appropriate course of action when finding an unattended duck nest is non-interference, as disturbing the area may cause a temporary absence to turn into a permanent one. Moving or interfering with a nest containing eggs or young is illegal for native species under the Migratory Bird Treaty Act. This federal law protects the birds, their eggs, and their nests from unauthorized disturbance.
If a nest is located in a high-traffic or vulnerable area, the best approach is to place a temporary barrier or sign nearby to alert people and keep the area undisturbed. Handling the eggs or attempting to move the nest is prohibited and often results in the hen not returning to the clutch. If the eggs are visibly damaged, or if the hen appears injured nearby, contact a licensed local wildlife rehabilitator for guidance.