Friday, October 22, 2010
A good three hours into our bird walk on the beautiful sunny morning of October 9, as some folks were starting to worry whether they would ever get home, our group spotted a small diving duck out toward the center of Greenough Pond. Well, it looked like a duck and swam like a duck, but in fact it wasn’t a duck. It was a Pied-billed Grebe (we soon spotted a second one), which neither walks like a duck nor quacks like a duck.
The Pied-billed Grebe is a small waterbird, smaller than our smallest ducks, drab brown in color, with a puffy white rear end but little to speak of by way of a tail. Like other grebes, it has a longish, thin neck and a small head. Its common name refers to the prominent black patch on the pale bill, visible in the photo (taken in springtime), but not on the birds we saw at Greenough. The bill is only pied (meaning patches of different colors) when the bird is in breeding plumage; in fall and winter it is a plain light gray.
This bird lives on ponds, lakes and marshes, and feeds on the various forms of pond life – insects, crustaceans, fish, snails and frogs. It also sometimes eats feathers, apparently to cushion the stomach from sharp bones.
The scientific name is Podilymbus podiceps, both parts of the binomial derived from the Latin podicis for rump and pedis for foot, with the Greek kolymbos for diver worked into the genus name. “Rump-foot” refers to the placement of the feet way back at the rear end of the body. They are not webbed as such, but the toes have wide lobes on each side creating a similar effect. This combination of lobed toes with rear-end placement together with a sleek body and dense bones makes grebes excellently adapted for swimming underwater. The downside is that legs that far back are not much use for walking and, like loons, grebes have difficulty moving around on land. They are also fairly weak fliers and skitter along the water when taking off. Since they generally migrate at night, they are rarely seen out of water.
A really neat trick of the Pied-billed Grebe is its ability to submerge like a submarine when alarmed. By contracting its muscles and compressing its feathers, as well as exhaling, it can slowly sink down low in the water, leaving just its head visible. This can make it very hard to spot. Sometimes it completely submerges and resurfaces in the shelter of reeds.
The range of the Pied-billed Grebe covers the entire United States and extends up into southern Canada and down into South America. It is the most common species of grebe in North America, the only one found inland in the east. A couple of its relatives, Red-necked and Horned Grebes, can be found on our coastal waters in the winter. Natural Heritage lists the Pied-billed Grebe as endangered in Massachusetts. This refers to its breeding status, and the recent Mass Audubon Breeding Bird Atlas project, just like its predecessor 30 years ago, has only a handful of confirmed breeding records. The Sudbury River Valley was historically a breeding stronghold for this species, but their numbers declined drastically in the mid-20th century. A pair successfully nested at Great Meadows in Concord last year and I found a juvenile this last July on Fawn Lake in Bedford.
They are more common in migration, especially in the fall, but generally solitary, rarely seen in numbers. October and November are the months when you are most likely to find a Pied-billed Grebe in Carlisle. As well as Greenough Pond, I have also seen them on the pond by the Maple Street bridge.
Peterson Field Guide: Birds.
The Birder’s Handbook, Ehrlich, Dobkin and Wheye
Massachusetts Breeding Bird Atlas, Peterson and Meservey.
The Sibley Guide to Bird Life and Behavior. ∆
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