Birder’s Notebook: Red-breasted Merganser
Red-breasted mergansers always surprise me. Every summer as broods of pintail, harlequin, teal, wigeon, shoveler and scaup ducklings appear on our ponds and waterways I fret —what has happened to the mergansers?
This summer was no exception. Then, much to my delight, in late July and early August, as other ducklings were close to fledging, large merganser families appeared. Just as they always do.
These dramatic, saw-billed, diving-ducks with flamboyant crests are late nesters with a long incubation period, so it is normal for their ducklings to show up late on the scene.
Red-breasted mergansers are found in arctic and subarctic regions throughout the world where they breed in cool northern waters with abundant small fish.
In early to mid-May, the first spring migrants typically arrive in our region where they are a common and widespread breeder along ponds and waterways throughout much of the Seward Peninsula and southern Norton Sound.
Impressive courtship rituals begin in marine waters and continue on inland nesting grounds. They put on quite a show, often with one or more males simultaneously courting a single female.
Males shake their crested heads and “salute” and “curtsy” to the female of their choice, often initially getting a chilly reception of total disinterest or even a sharp jab from the “saw-bill” of their desired mate.
If a male is successful, eventually, the female shows her acceptance by holding her head high with her bill pointed downward, rapidly bobbing her neck and head up and down. A monogamous bond is usually formed for the breeding season.
Red-breasted mergansers are gregarious birds and are not territorial. They may nest in association with other birds of their own or different species. After exploring the nesting area for up to three weeks, the female selects a nest site on the ground, near water, well concealed by vegetation.
The female scrapes a shallow depression in the ground and forms a nest cup with grasses and vegetation from the immediate area. She adds down that she plucks from her belly to insulate the nest, thus forming a brood patch.
Egg laying on the Seward Peninsula peaks during the second and third weeks of June. An average of nine eggs is laid, but up to 13 eggs have been reported. An egg is laid every day and a half and incubation begins when all eggs have been laid.
Incubation is done entirely by the female. Males leave the breeding ground as soon as incubation begins, moving to coastal or inland waters where they join groups of failednesters or non-breeders for the molt.
During incubation, the female frequently moves and turns the eggs, covering them when she leaves the nest to feed. If she is startled or feels threatened, she will slink away from the nest, flapping her wings before flying, thus drawing attention away from the nest.
Incubation lasts about 29 days. In our region, hatch typically occurs the last week of July or the first week of August. The chicks are down-covered and ready to leave the nest less than 24 hours after hatch. They are able to feed themselves as soon as the female leads them to the water.
Initially the female broods the young to keep them warm, leads them to suitable feeding areas, keeps the brood together and warns and protects them from predators.
The young fledge in late September or early October, 60 to 65 days after hatch.
Red-breasted mergansers in our region feed on small fish, crustaceans and aquatic insects. Sticklebacks are particularly important for small ducklings.
Mergansers are often seen snorkeling along the surface with eyes submerged as they search underwater for prey. They dive to capture food, grabbing it with their serrated bill that is adapted to snatch and hold slippery fish.
Flocks of adults and ducklings will fish cooperatively, swimming in a line formation, beating the surface of the water with their wings to herd fish into position where they can dive and catch them.
Mergansers have a high metabolic rate that makes them well adapted to life in cold water and climates. However, they must consume many calories to fuel their fast metabolism. Adults must eat 25 to 30 fish per day. Ducklings, in their first 20 days after hatch, need to consume 74 to 85 percent of their body weight every day.
Typical of diving birds, redbreasted mergansers are awkward on land and seldom walk. Their legs are located far back on the body so their feet can propel them efficiently when swimming and diving.
Although takeoff requires a run over the water, red-breasted mergansers are strong fliers with rapid wing beats. They are one of the fastest ducks on the wing, clocking speeds of up to 81 miles-per-hour!
The mergansers that breed in our region typically winter in near-shore, marine waters of southern and southeast Alaska and along the Alaska Peninsula and the Aleutian Chain. A few are occasionally seen in the Bering Sea. Many remain in our region until freeze-up. In fact, in recent years, a few have even showed up for
Nome’s Christmas Bird Count.
At this time, the red-breasted merganser’s widespread, circumpolar distribution and abundance make them a species of low conservation concern.
With that, plus having now written about the merganser’s lateseason nesting habits, perhaps next July I won’t worry when all the other ducks show up with ducklings in tow and merganser families are nowhere to be found. They will come.