It’s hard to picture a duck flying straight into a cavity in a tree, but there are several species of waterfowl that do just that in order to incubate their eggs in a relatively safe location. The female Hooded Merganser selects a nesting site in a living or dead tree cavity or in a handmade nest box. Once mating and egg-laying has occurred, the male disappears, leaving his mate to raise and care for their offspring.
Within 24 hours of her eggs hatching, the female calls to her young from the cavity opening or from the water below, encouraging them to leap up to the opening and hurl themselves out into the world. The entire brood departs the nest within a couple of minutes. As soon as they hit the water, the precocial young ducks are swimming, diving and feeding on water boatmen, backswimmers, diving beetles and other aquatic invertebrates.
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A blind is a wondrous thing, allowing you to observe natural behavior in a natural setting. Having watched beavers for over 50 years, I thought I had seen most of what there is to see regarding Beaver behavior, but this particular morning I was witness to a new activity, namely a game of tag.
The resident Beaver spent the better part of half an hour chasing ducks around its pond. A pair of Mallards were subjected to this annoyance first. When approached, the Mallards would swim away together, with the drake quacking loudly, but obviously weren’t put out too much by this game as they tolerated it for about ten minutes before taking off (undoubtedly in search of a more serene body of water).
No sooner had the Mallards left than a pair of Hooded Mergansers arrived. The Beaver greeted the newcomers and proceeded to chase them around and around the pond, occasionally catching up to them, and then restarting the game all over again. Eventually the mergansers, too, departed, leaving the Beaver king/queen of his/her castle. (Thanks to Mike Keating for photo op.)
Keep your eye out for increasing numbers of Hooded Mergansers (Lophodytes cucullatus) on open lakes, ponds and rivers. Although these birds can be found in most of New England year-round (some overwinter as far north as ice permits), much of the population overwinters in the Southeast. Hooded Merganser migration northwards begins particularly early in the spring — they often arrive on breeding grounds within days of ice out. (Photo: Hooded Merganser pair, female in foreground)
Before Hooded Mergansers seek out their nesting cavities in snags and stumps they engage in extensive courtship displays. Males tend to outdo females when it comes to these displays. As the accompanying photograph illustrates, courtship occurs in small groups consisting of at least one female and several males. Males engage in many more types of displays than females. The extent of female courtship consists mainly of head-bobbing and head-pumping. Male displays include crest-raising, head-throws with turn-the-back-of-the-head, head-pumping, head-shaking, upward-stretch, upward-stretch with wing-flap and ritualized (repeated) drinking.
Head-throws (see male in foreground of photo) are the most elaborate display. With crest raised, males bring their head abruptly backward touching their back. A rolling frog-like crraaa-crrrooooo call is given as the head is returned to the upright position and turned away from the intended female. This call sounds so much like a frog that the first time I observed courting Hooded Mergansers I thought it was pure coincidence that I was watching male mergansers display while Leopard Frogs were simultaneously giving their snore-like call. In actuality, the displays as well as the vocal accompaniment were being produced by the mergansers. (Note that one female Hooded Merganser appears not to be all that impressed.)
Hooded mergansers are present in most of the Northeast year round where there is open water, but many move south and southwest in winter. Some actually migrate north to spend winters in the Great Lakes and southern Canada. Their numbers swell in March and April, when migrants are passing through as well as returning. Often within days of when the ice goes out, this smallest (and arguably the most beautiful) of the three North American merganser species appears.
The courtship ritual of hooded mergansers takes place in groups of one or more females and several males. The males raise their crests, expanding the white patch, and engage in behavior known as head-throwing. They jerk their heads backwards until it touches their backs, while giving a frog-like croak. Females court by bobbing their heads and giving a hoarse quack.
Female breeding hooded mergansers select suitable cavities in both live and dead trees in which to nest. Stumps and snags near or in forested wetlands are their preferred nesting sites. Nest boxes are also used by this species, with those over or near water being the most sought after. After a month or a little more, the eggs hatch and downy, day-old chicks jump to the water (or ground) below, in response to their mother’s vocal urging.
Hooded Merganser ducklings typically leap from their cavity nests in trees within twenty-four hours of hatching. Long claws on their feet aid them in climbing up to the opening of the cavity in order to join their mother who is calling from below. The ducklings feed themselves (aquatic insects and invertebrates) from day one, and are capable of shallow dives as soon as they leave their nest. The mother (who has been their sole caretaker since she started incubating the eggs) often moves her brood downstream to larger lakes, rivers and bays from smaller streams and ponds near the nest site. Eventually she leaves her young, anywhere from a month or two after they hatch, often before they can fly.
Although most of New England has Hooded Mergansers year round, we see them most frequently in the spring and fall, when Canadian-nesting individuals are migrating north. They stop to re-fuel in wetlands where they are well adapted for capturing and eating fish, insects and crayfish. The nature of the changes their eye lenses can make, coupled with the high degree of transparency of the membrane that covers their eyes under water give them superior vision under water. Their success in holding onto the struggling prey they capture is greatly increased by the serrated edges of their slender bill. (Photo: female Hooded Merganser)