YELLOW-BELLIED SAPSUCKER 127 



ing 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 on- 

 coming 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 plen- 

 teously 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 oppo- 

 site 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, lei- 

 surely 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 lim.b, 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, 



Eaton (1914) notes that "during the migration it is evident that 

 the male birds arrive first, for during 15 years of continuous records 

 which I have kept with this object in view I have found that male 

 birds are the first to be seen each year and no females are seen for 

 several days after the first males arrive." 



Audubon (1842) records the following unique observation: 



While travelling I observed that they performed their migration by day, 

 in loose parties or families of six or seven individuals, flying at a great height, 



