2011 Field Diary Excerpt

While monitoring inside the bird boxes for eggs and nesting birds, we came across a Hooded Merganser (Lophodytes cucullatus) in a Wood Duck box near a marsh. We had previously seen a male of this species in the area and we were hoping they would decide to nest here. Although most mergansers are fairly tolerant of disturbances while in their nest, we didn’t want to agitate her more than necessary and we weren’t sure if she was on eggs yet or not. Hooded Mergansers incubate their eggs for an average of 33 days, but we had no way of knowing when (or even if) her eggs were laid. They are known to lay eggs as early as February and as late as June, however, once the eggs hatch, the ducklings are only in the nest for approximately 24 hours.

The Hooded Merganser (Lophodytes cucullatus) is a year-round resident of the area. The female of the species selects the nest site as early as the summer before her breeding attempt and prefers to use the same nest box as the previous year. If this brood is successful, it is highly probable that this merganser will nest here again next year. Only the female constructs and maintains the nest; however, no new nesting material is added. The feathers seen surrounding the nest bowl were plucked from the female’s belly to create her brood patch and add to the insulation in the nest. The female will incubate her eggs, for approximately 33 days.  Once hatched, the ducklings will leave the nest within 24 hours. The female will check for predators, and then call to the ducklings from the water below. The ducklings can feed themselves and dive for food from the first day after leaving the nest. The male merganser abandons the female and young after the initial incubation process begins and all brooding and raising is completed by the female. The young will leave their mother after approximately 30 days.

The Hooded Merganser (Lophodytes cucullatus)  had a partially successful brood and the ducklings hatched. A couple of the nestlings can be seen with their mother in the photographs. Once the babies were strong enough, the mother left the nest and called to them from the ground below. The ducklings continued to jump up and down until they found the opening and jumped down to their mother, waiting below.

Hooded Merganser nests are often parasitized by both their own species and other species. Wood Ducks and other Mergansers will sometimes lay their eggs in the nest of a Hooded Merganser and leave the eggs for that mother to care for.