CONTRIBUTED BY WINSOR MARRETT TYLER _Spring._--It is spring in the Transition Zone when in April the yellow-bellied sapsucker passes through on the way from its winter quarters to its breeding ground in the Canadian Zone. If spring is tardy most of the trees may be leafless, but many of them have blossomed, and the sap is running. At this season the sapsucker is light-hearted and jaunty compared to the sober, quiet bird that visited us the autumn before. The breeding season is near at hand, and if two birds meet they often engage in a sort of game, a precursory courtship, wherein one bird flies at the other in a playful attack; the other eludes the rush of the oncoming bird by a sudden, last-minute retreat--winding around the branch on which it rests, or sliding off into the air. In these pursuits in and out among the branches we are impressed by the agility and grace of the birds and by the easy way they direct their course through the air. They do not appear to impel themselves by strength of wing alone, but, especially in their slanting descents, they let the force of gravity pull them swiftly along, and then, by the impetus of the speed attained, glide upward to a perch. They seem to swing from branch to branch with little effort, slowly opening and closing their wings to guide them on their way. As we watch them we are reminded of trapeze artists in the circus. But the new sap is running, and the birds quickly tap the supply by drilling into the bark of their favorite trees and drink of the sap as it flows freely from the wounds. Every spring the birds come to a sturdy yellow birch tree on the Boston Public Garden, a species of tree with which they must be familiar on their breeding grounds in the north. The sap flows plenteously in mid-April from the many punctures that the birds make; it wets a large portion of the trunk of the tree and often drips to the ground from the branches. The birds stand clear of the tree as they feed at the sap wells with only the feet and the tip of the tail touching the bark. The tail is braced against the trunk at an angle of about 45°, and the feet reach far forward to grasp the bark opposite the bend of the wing. I have never seen a sapsucker crouch against this wet bark as a downy woodpecker commonly does when digging out a grub--like a cat hunched up lapping a saucer of milk. When a bird wishes to move to a point below where it is perched, it jumps from the tree and floats in the air, then turning, with its wings held out somewhat, dives head-downward, drifting in an easy, leisurely manner as if moving under water; then, just before alighting, it rights itself. If you come too near, the sapsucker scrambles around to the rear of the limb, and if you step close up to the tree, the bird starts away in free, sweeping curves, like a skater over the ice, the white in the wing flashing out.