This is one of a series presented by the National Aviary, which works to inspire respect for nature through an appreciation of birds.

So, what looks like a duck and swims like a duck, but doesn’t quack like a duck? Well, it could still be a duck, because many species of ducks don’t quack (instead they whistle, purr, cluck or squeal), but it could also be a grebe, a loon, or a coot; duck-like water birds of a different feather.

Because all ducks and other water birds need open water to rest and feed, they generally fly just far enough south in fall so that they can reach places to spend the winter where open water doesn’t freeze over completely. Then, beginning in late February, as spring gains ground and frozen waters melt, these same birds reverse course and follow the thawing water bodies northward all the way back to their nesting grounds, which for many is the boreal forest and tundra of northern Canada.

Here in Western Pennsylvania, birders can glimpse the peak waterfowl migration for about a month in fall (November) and spring (March). On a good day afield, a birder can hope to see 25 species of waterfowl (which includes the ducks, geese, and swans), and several other species of water birds: Horned and pied-billed grebes, common loons and American coot. Loons have webbed feet similar to ducks, but grebes and the coots have very distinctive feet with no webbing in between their toes — instead they have broad fleshy lobes fringing each of their toes.

The American coot belongs to a family of birds called rails, not usually known for swimming, but rather for skulking through the dense reeds of a marsh. Coots, however, are more duck-like and are regularly seen (sometimes in very large numbers) on the open water along with migrating ducks. They are easily identified by their solid dark gray body and bright white bill. Although they will feed at the surface, and even on land adjacent to the water, they are excellent divers and get much of their food underwater.

Compared to surface feeding ducks, such as mallards and wood ducks, grebes, loons, and the so-called diving ducks all have their legs positioned at the rear end of their bodies, which is very adaptive for propelling them underwater, but not for springing up directly off the water to take flight. Consequently, unlike mallards which can take flight by springing directly up off the water, all diving water birds have to make a long paddling takeoff in order to get airborne.

One of the nice things about going waterfowl watching at this time of year is you can often see a lot of birds, and a lot of different kinds of birds, all in one or a few spots. But, because they often are swimming at a considerable distance from the shoreline, in order to see them well and identify them, a high power spotting scope usually is required.

If you think you might like to try waterfowl watching, I will be leading another all-day bus tour to several waterfowl migration hot spots north of Pittsburgh on Saturday, March 25, and I’ll have a spotting scope we can use to see all those interesting and beautiful water birds. For more information, and to register, go to https://www.aviary.org/special-events/wonderful-waterfowl .

First Published: March 15, 2017, 4:00 a.m.