The Carlisle Mosquito Online

Friday, March 14, 2008


Biodiversity Corner - Hooded Merganser

One hundred and five years ago today, on March 14, 1903, President Theodore Roosevelt

(Photo by Katherine Hubbard)

designated Pelican Island in Florida as the first “Federal Bird Reservation.” The purpose was to protect the birds (mainly pelicans, herons, and egrets) from plume hunters. The tiny island (three acres) was the first unit in what became the National Wildlife Refuge system which today has over 93 million acres. The Hooded Merganser seems an appropriate topic at this wet time of year and in recognition of the bird reservation anniversary.

Name. The Hooded Merganser is Lophodytes cucullatus. The Common Merganser and the Red-breasted Merganser are close relatives but both are in the genus Mergus. The name “Merganser” comes from the Latin words mergus meaning diver and anser meaning goose. The Mergansers are indeed divers as opposed to dabblers like the mallard or the wood duck. The “goose” part of the name seems a little off the mark but swans, geese and ducks are all in the same family, the Anatidae, so the naming logic is not stretched so thin as to break. Mergansers are sometimes also called saw-bills or fish-ducks.

When and where seen. Tom Brownrigg alerted me to the Hooded Mergansers at the Greenough Pond. He saw a pair on the east side of the Maple Street bridge on March 6 around 1 p.m. I had a look on March 9 and saw two pairs near the road and a small flock (maybe ten) on a protected cove in the broader part of the pond. They were still there on March 10 in the company of a pair of Canada Geese and a pair of beavers. Hooded Mergansers are migratory ducks. They tend to spend the winter much further south and west of here and return north of here in the spring for breeding. Carlisle is in the narrow band where the borders of the winter and summer ranges overlap but so far the ducks are not known to over-winter here or to nest here – although last summer there was a single nesting pair in Concord at the Great Meadows National Wildlife Refuge. The male Hooded Merganser in his breeding plumage is a strikingly handsome bird worth seeing and this is the time of year when your chances are best – late winter or early spring when the ice is just breaking.

Distinguishing characteristics. The Hooded Merganser is most easily recognized this time of year by the very distinctive “hood” or crest of the male. When the hood is up, it gives the head an almost circular shape – as in the photo. The white patch on the side of the face, sharply outlined in black, is so brightly white it reflects the light and makes it fairly easy to spot these birds out on a pond without binoculars. With binoculars you can see the other distinctive black and white markings and the tawny sides.

Hooded Mergansers are known affectionately by birders as Hoodies – and I can’t think of hoodies without (unfortunately) thinking of the Belichick bird. If you parse the word “Belichick,” you come up with something like a “beautiful little bird,” which I guess is fine since we call a duck a goose. While the Belichick hoodie is drab and dingy and suitable for solitary brooding, the Merganser hoodie is pristine and elegant and suitable for enticing females for breeding. Female Hooded Mergansers are grayish-brown with hoods of a cinnamon-brown color. The hoods are not as dense as those of the male and when raised they are a soft pinkish brown and look like a spiky punk hair-do. Hooded Mergansers are relatively small ducks – about 18 inches from tip of bill to tip of tail.

Adaptations for diving. These ducks are expert divers. They have evolved in a way that allows them to modify the refractive properties of their eyes for better underwater vision and thereby improve their ability to find prey animals like small fish, frogs, and invertebrates. They also have a third eyelid, called a nictating membrane, which is transparent and protects the eye during swimming – rather like goggles.

References. Cornell Lab of Ornithology at (search on “hooded merganser”); National Geographic Field Guide to the Birds of North America; The Sibley Guide to Birds, David Allen Sibley. ∆

Please feel free to write the Biodiversity Corner on some species you have seen recently – or tell me what you are seeing. The only requirements are that the subject exists in the wild and was seen in Carlisle. Send a note to

© 2008 The Carlisle Mosquito