BIRDS OF NANTUCKET
ASAW-BILL
by Kenneth Turner Blackshaw
You've heard of a 'sawbuck,' but what about a 'sawbill?' A sawbuck is a ten-dollar bill. Perhaps a sawbill is money? But remember - this is a bird column. This must refer to a bird's bill with teeth. This makes me think of the saying that chickens don't have teeth. And that in turn ties into the saying that something is as scarce as hen's teeth. Okay, Kenny - where are you going with this?

Hooded Merganser

We actually see three species of 'saw-bills' here on Nantucket. It turns out this is a nickname for a merganser, a type of duck. All mergansers have serrations along their bill that help them hold onto the fish they catch. The three we find here on Nantucket are the Common, Red-breasted, and the Hooded. The Hooded Merganser is our subject this week.

This was a very rare bird on our island when Edith Andrews was teaching me my birds back in the 1950s. Indeed it had only been found on Nantucket three times, and one of those times was way back in 1877. It appeared to be a rather stunning duck as it floated there with the other two mergansers in my Roger Tory Peterson field guide. The picture showed this marvelous white hood that could apparently be elevated straight up or retracted flat against the back of the head. What a sight to see! Alas, I had to wait years to finally see one.

The strange thing is that if you are starting out as a birder now, you can easily find Hooded Mergansers on most of the fresh water ponds and salt marshes on the island. They appeared first on a Christmas Bird Count in 1960 and have been found on every count since 1973. Now we typically find over a hundred, and in 2006 there were 229.

People frequently ask me if there are as many birds around as there used to be; birds like the Hooded Merganser make it difficult to answer that question. This species is doing very well, unlike our songbirds that winter in Central and South America. So some species are doing very well and others not. We don't always understand why.

One thing we note is that while Hooded Mergansers are thriving, their Red-breasted cousins are not. That species peaked in 1986 with over eight thousand at the Christmas Bird Count. The 2007 count only produced 852. I'll let you think about this while we learn more about Hooded Mergansers.

Of the three mergansers this is the only species unique to North America. Its scientific name is very different as well, Lophodytes cucullatus, translating to a hooded, crested diver. It is the only living species of the genus Lophodytes. Its solitary close relative Lophodytes floridan apparently was driven to extinction during the last ice age, perhaps a casualty of 'global cooling!'

I've mentioned the hood but what about the rest of the duck? The drakes are very smartly attired, black on the face and back, rusty on the flanks with a white chest. The females are very different, mainly gray to brown with a reddish, paddle-shaped crest at the back of the head - no hood! Both sexes have a long narrow bill with a hook at the end, and yes, little teeth along the edge of the upper mandible.

These are ducks that nest inside the trunks of trees. They like fresh water swamps and nest from Florida up into central Canada but not on Cape Cod or the islands. It's not unusual for them to produce a dozen chicks up in their tree penthouses and many of them jump 60 or 70 feet down to the ground well before they have any hope of flying. In some cases Mom has been seen carrying them down in her beak.

The Cree Indians of Saskatchewan call these birds 'Beaver Ducks'since they will occasionally nest in deserted beaver houses, entering and leaving the nest through an underwater passage.

Like the other mergansers, Hoodeds find their food under water, diving and swimming rapidly using both feet and wings. They have a specially developed nictitating membrane or third eyelid that is nearly transparent and functions like a diving goggle to improve their underwater vision. Their flight is direct and very rapid, hitting over 90 miles per hour.

Just a little more about how many Hooded Mergansers there may be. There are certainly more on Nantucket than there used to be. Aresearcher back in the 1970s estimated there were 76,000 but then it was pointed out that that many were actually shot by hunters every year! Now the estimate is 270 to 385 thousand Hooded Mergansers in North America.

On our fair island we expect to see them from early October until the end of April and find them common during the middle of that period. Good places to see them are all the ponds on the south side of the island as well as salt marshes like the Cricks and Folger's Marsh. Take a look at them in your bird book and I'm sure you'll want to pay

at least a sawbuck to see a saw-bill! 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.