Donald Nutchey, age 10, of Iroquois Falls, Ont., Canada for his question:

DO BIRDS SING OR WHISTLE?

When you whistle a merry tune, you use your lips, tongue and teeth. A bird has no lips and no teeth yet he can whistle as well as you can. He also can warble and trill like a glee club singer. Some birds prefer to whistle, others prefer to warble songs and a few can copy human words. But they make all these sounds in their own way.

A bird has a voice box down his throat, somewhat like the human voice box. As he breathes, puffs of air vibrate small flaps of skin to form the sounds. The sounds are shaped and molded inside his mouth to form whistles, notes or words. Usually he opens his beak to let out the sound but sometimes he sings or whistles with his mouth closed.