Jim Malder, age 14, of Brackenridge, Pa., for his question:

Which bird flies the fastest?

The fastest four footed land animals can outdistance the fastest swimmers. All of them are slowpokes compared with the fastest flying birds. The various speeds of the entire animal kingdom range from inches to hundreds of miles per hour (m.p.h.). And naturally each of the more than a million species must move fast enough to capture his food  and also to escape most of his famished foes.

Clocking the top speed of a bird is not as easy as one might suppose. Most of their fast flights are over short distances, and who knows when a bird is doing his best? Clocking migrating birds must be done by widely separated observers—who must allow time out for the flight stopovers. Flocks of canvasback ducks migrate at average speeds of 70 m.p.h. hour and the handsome Canada geese attain 60 miles.

Obviously flocks of birds do not reach their top speeds during their long migratory flights. The fastest birds are loners, who must pursue fast prey in order to survive. Some years ago, it was thought that the fastest flying bird was the Indian swift, who must swoop around at high speed to catch his dinner of fast flying insects. His top speed was found to be somewhat faster than 100 m.p.h.

At that time, the runner up was thought to be the peregrine falcon, alias the duck hawk. His top speed is attained as he swoops like a dive bomber down on his fast¬flying prey. His plummeting plunge was clocked at 100 m.p.h.

However, certain bird experts were not satisfied with this estimate and quite recently some very sophisticated experiments were conducted to verify the facts. We now know that the downward plunge of the peregrine can be at least 250 m.p.h.  and probably faster. So far as we know, no other flying bird can match this fantastic speed.

The handsome peregrines, large and small, are freckled falcons with mighty claws, keen eyes and hooked beaks. They are, of course, birds of prey who must be faster than their fast moving victims. Our native duck hawk peregrine is a 15 in. to 19 in. bird who pounces on ducks, known to be fast fliers and artful dodgers.

The mighty flying muscles of the average peregrine enable him to maintain a fast, steady speed during the strongest gale. But his greatest speeds are reached when he folds his great wings to his sides and plunges downward like a streamlined missile.

How he breathes during his plunge was a mystery until scientists investigated the insides of his nostrils. Each has a small rod ending in a pair of fins. These built in gadgets filter the rushing air into small swirling currents.