"Those are not true teeth, like ours, to chew with. You know a good many very different things are called teeth—those on a rake, for example, or a comb, or a cog-wheel. A Duck's teeth are horny like the skin that covers its whole beak, and act like strainers. When a Duck dabbles in the water, as you have all seen tame ones do, the water that gets into its mouth runs out at the sides between the teeth, but whatever food there is in the mouthful of water gets caught in the teeth, and can then be swallowed."
"Please tell us," continued Rap, "how many different kinds of Ducks there are in our country?"
"About forty," answered the Doctor; "but I shall not trouble you to learn more than a few of the common ones. They all belong to one family, which also contains the Geese and Swans. They are divided into three groups—Fishing Ducks, River or Fresh-water Ducks, and Sea Ducks.
"The Fishing Ducks are great swimmers and divers, living chiefly on the fish they catch by chasing them under water. Their beaks are narrow, hooked, and sharply toothed, which makes it easy for them to hold their slippery prey. But this oily food makes their flesh so rank that none of them is fit food for House People. They are all called Mergansers, and we have in this country four different species.
"The River Ducks are those that we see mostly in the spring and fall migrations; they have the handsomest plumage and the most delicate flesh. They feed along shallow rivers, ponds, and lakes, after the manner of barnyard Ducks—for the Mallard is one of them, and tame Ducks are domesticated Mallards, as I told you. In feeding, they bob head downward in the water with their tails straight up in the air, to find the roots, seeds, insects, small shell-fish, and other things they like to eat. They build very good nests, usually on the ground, and warmly lined with their own down, which the parent plucks from her breast to cover the eggs. The color of the eggs is always greenish, gray, drab, or buff, never with any spots. Most River Ducks nest in the far North, but there are some exceptions. The Wood Duck that Rap saw by the lake is one of these exceptions, and has the most beautiful plumage of all our Ducks. It does not build its nest on the ground, like most others of its family, but in a tree hole, like an Owl or a Woodpecker."
"How can the little Ducks get down to the ground—do their wings grow strong very soon?" asked Nat.
"You have seen that most birds come from the egg quite naked, and stay in the nest till their feathers grow, like Canaries and all other song birds, while others are hatched all covered with down, the same as Chickens are. The young of those living in open exposed places, such as sea and shore birds, are thickly clothed with down when hatched. Such downy plumage is not exactly like the feathers that sprout after a while, but it answers the same purpose; for the little things could not run about or swim if they were naked, you know."
"Yes, Ducklings are all downy; for I remember those that came out in June up at the Farm were, and their tiny little wings were as cunning and cute as could be," said Dodo.
