BIRDS OF NANTUCKET
BIG BLACKHEAD?
by Kenneth Turner Blackshaw
Ihope that's not the skin condition on the person next to you in the elevator. Oooh - break out the Clearasil. But of course this is another bird nickname. Does 'big bluebill' sound better to you - perhaps the state flower of Texas? But no, that would be the 'bluebEll.' Our feathered friend is known by both these names.

Greater Scaup

This is a bird that can be tricky to identify but you need to remember what Edie Ray says: "G's are round and L's are pointy!" I'll just let you mentally munch on that as we proceed.

You can guess from the illustration that this week's bird is a duck. You can even guess that the boys are very different from the girls. This is a duck that is very common here every winter and flies a long way just to get here. Birders know it as the Greater Scaup (rhymes with 'stop'). They have a very close relative, the Lesser Scaup, that is also common here. You may think that size matters, but only to the birds. Since the sizes overlap, birders don't get much of a break.

The scientific name, Aythya marila, a charcoal waterbird, is kind of generic and boring, could describe many birds, some of them ducks! They are close relatives of other diving ducks like the Canvasback and the Redhead. The name 'scaup' is more interesting, relating to an old Scottish word for a bed of shellfish and actually has the same origin as the name for Nantucket's favorite shellfish, the scallop!

Greater Scaup nest on the tundra of northwestern Canada and Alaska. It is an abundant duck. Scientists have trouble distinguishing Greater from Lesser (more on that later, watch your Gs and Ls) so they estimate the total of both species together. There are over five million in the U.S. There are millions more in Europe and Asia, but those are all Greater Scaup over there. The Lesser Scaup is a strictly American species.

Scaup nest on the ground very near water. They weave the nest with grass stems and line it with feathers right from the mother's belly. Oftentimes they nest in colonies with many nests close together. Once the eggs are laid Mr. Scaup abandons his family and heads out into the salt water. There, like most ducks, he sheds all his flight feathers in his annual molt and spends several weeks unable to fly as he grows his new wings.

Mrs. Scaup spends a month and a half incubating her eggs and teaching her precocious young to catch insects, swim and dive. Diving is a key part of this species' existence. Almost all their food is secured this way and it is also how they hide when startled. They are unable to spring into the air like mallards. Instead they run along the water to take off into the wind.

Scaup start arriving on our island in October and become more abundant in November and December. A typical Christmas Bird Count will find over 500 and they've been observed on every count. One of the best places to find Greater Scaup is Sesachacha Pond on the east end of Nantucket. Typically there are several hundred of them bobbing up and down in the middle. It takes a spotting scope to really appreciate them. The males appear black on both ends and white in the middle. The females are solid chocolate brown with a white patch around the bill. Scaup, Greater and Lesser, are the only ducks you are likely to see that have a stripe down the wing in flight.

When I was learning my birds a lot was made of the 'fact' that Greater Scaup show a greenish gloss on their head and Lesser Scaup have a purplish gloss. This seems useful when gazing at a picture in a bird book but becomes very frustrating when staring at an actual bird since the sunlight must strike the bird's head just right to see any color at all.

David Sibley's new bird guide tells us that the whole color gloss thing really doesn't work at all. Depending on the way the light strikes the bird, you can see either color. Oh brother! Actually birders have been experiencing this paradox right along and thinking we were visually deficient or something.

The current best way to identify scaup goes back to Edie Ray's method in the beginning of this article. Greater Scaup have nice round heads and Lesser Scaup heads look pointy at the top. G's are round (for Greater) and L's are pointy (for Lesser). Even this doesn't always work, but it's the best we can do.

The other thing is that Greaters prefer salty water. If you see a scaup in Miacomet Pond for instance, it's likely to be a Lesser. You can work backwards on this trick as well. Since we see many Greater Scaup in Sachacha Pond that gives you a clue that Sachacha is a salty pond.

You can see these hardy diving ducks all through the winter. When the ponds freeze they head for the ocean. Most all of them are gone by the first of May as nature calls them a thousand miles or more to the northwest to lay their seven to 10 eggs and keep the scaup population thriving. Scaup live as long as 18 years so they log a lot of miles in their lifetimes. An old Greater Scaup must know the bottom of

Sesachacha Pond really well. I

George C. West creates illustrations for these articles. If you enjoy 'social' birding, join the Nantucket Bird Club at 8 a.m. Sundays in front of Nantucket High School for a two to three hour birding trip. Call 228-1693 for more information. To hear about rare birds, or to leave a bird report call the Massachusetts Audubon hot line at 1-781-259-8805. Ask Ken a question at: kenandcindy1@comcast.net