John Moan, age 13, of Coventry, Rhode Island, for his question:

What are crossbills?

Now is the time to come to the aid of all our native birds. And getting to know them is a good place to begin. For example, you may have seen a troupe of crossbills and mistaken them for cheerful little sparrows. By nature they are gentle and rather shy    and they flit from perch to perch too fast for close inspection. Most likely you did not get a chance to notice that they are called crossbills because they have crossed bills.

The crossbill belongs to the finch family Fringillidae, along with 125 species of canaries and song sparrows, grosbeaks and buntings    plus, of course, the colorful assortment of pretty little finches. All these charming perching birds have strong stubby bills, just right for eating tough small seeds. The crossbill goes one better. The two halves of his sturdy bill are slightly curved but the upper beak tips down and the lower beak tips up. When his mouth is closed the two tips cross over.

This unusual bill is a splendid pincers and scissors type tool    just right to cope with the crossbill's favorite food. He spends most of his time in tall, dense conifer forests of pine, larch and spruce. Here the seeds come packaged in tough woody cones    but the crossbill can open them up and peck out the goodies with no trouble at all. His menu also includes a few bugs and small berries.

Two crossbill species make their homes in North America. The females of both species wear olive tones of green and yellow that blend with the thick conifer foliage where they build their nests. The male red crossbill wears rusty red plumage, tinged with browns on his tail and wings. The male white winged crossbill wears the same rusty reds and dusky browns, plus flashy splashes of white on his wings and chest. He also has a white bar at the top of his remarkable bill    and a black pair of pirate moustaches sketched under his eyes.

Crossbills enjoy the company of their friends and relatives and usually live in smallish flocks. Their seed supplies vary from place to place and crossbills are born travelers. But unlike most traveling birds they ignore the seasons. Summer and winter, spring and fall find them flying north or south, east or west. A flock of red or white winged crossbills may arrive in Rhode Island at any time of the year. After a short stay, they may decide to take off in easy stages for Alaska, Idaho or the Carolinas.

However, these jet set birds take time out to give the very best care to their growing children. As a rule, their nests are in the lofty branches of tall conifers. They are neat, sturdy little baskets woven from twigs, grasses and rootlets and softly lined with bits of hair. The four to six blue eggs have a rash of brown freckles at one end. Mrs. Crossbill sits patiently on the precious eggs, blending invisibly with the sunny and shady speckles of the thick foliage. Mr. Crossbill brings food and serves her meals all through the waiting period.