Quality Time with Mergansers

I was scouting cut corn fields on a tip that migrating snow geese were stopping to feed and rest. It was 19 degrees with a 20 mph wind, so road hunting from the warmth of my truck seemed to be the best strategy.

I didn’t see snow geese but spotted a pair of hooded mergansers on a tiny, roadside  pond. Hooded mergansers are small, fast-flying diving ducks that are wary and intolerant  of disturbance. The pond, probably installed for erosion control, was no more than 50 feet across and rimmed with small trees and brush. Most small ponds in the area were frozen, so I assumed it was spring fed and healthy. Somehow I managed to ease the truck off the road and reach a vantage point without pushing the mergansers off the water. After a few minutes they settled and resumed normal activity, treating me to an hour-long demonstration on the feeding behavior of a pair of hooded mergansers.

Hooded mergansers; the male has just surfaced from a feeding dive.

In the spring, small ponds, swamps and rivers in wooded areas are preferred habitat for breeding pairs of hooded mergansers. Trees are an important habitat feature because this species, like wood ducks, nests in tree cavities. The recommended dimensions for an artificial nest box shed light on the nature of these cavities: roughly 24” high x 11” wide, with an oval-shaped  entrance hole about 4” wide x 3” high.

Brilliant black and white markings and chestnut flanks distinguish the colorful male. The white crest on his head, which he expands when courting, is an outstanding identifying feature for a bird on the water, even at long distances.

The female is drab but has the typical merganser silhouette: a distinct crest and long, slender bill.

Hen that just popped to the surface after a feeding dive

Mergansers are diving ducks. Strong, fast swimmers with long, slender, serrated bills, they are well-adapted for underwater fishing. The dive is abrupt and fast, lasting 5 to 10 seconds. 

While submerged, they search for small fish, frogs, crayfish and small aquatic organisms. In this case, aquatic vegetation on their bills and a worm-like invertebrate (?) caught by the hen suggest that they were foraging at the bottom of the pond.

When feeding, the pair was usually in close proximity to one another. I’m not sure why the hen became aggressive toward the drake, but I believe she was being a bit greedy over the subsurface food supply rather than fending off an unwanted suitor.

The weather failed to improve and the mergansers drifted toward cover near shore. I decided to let them be, grateful for the unexpected quality time and opportunity to observe the behavior of a pair of elusive wild ducks.

All photos by NB Hunter

 

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