When all the birds had disappeared except the vireos, I went in search of a new sap orchard. I soon found a clump of red maples containing two trees that had been tapped by woodpeckers. The belt of punctures on both trees was nearly a foot in width, but the woodpeckers did not show up during my three hours' tarry.
This woodpecker, the yellow-bellied (Sphyropicus varius), does not nest on the Cape, so had doubtless departed in migration, but three humming-birds were fighting for the sap-buckets, and a red squirrel settled matters by driving the hummers from one tree to the other.
YELLOW-BELLIED WOODPECKER.
The red squirrel was a new feature in a woodpecker's sap orchard. He did not cling to one spot, as squirrels do when tapping for themselves, but instead moved rapidly around the tree, thrusting his tongue into the drills for the sweet sap. I suppose the squirrel owned the territory where the maple-trees grew, and was more than willing that the woodpeckers should tap the trees for his benefit.
The drills made by the woodpecker extended through the outside bark and into the cambium layer. From my observation with a good glass, during several seasons, I found that the woodpeckers were after the elaborated sap that descends from the leaves, through the inner bark, and did not extend the drills into the wood where they would reach the crude sap flowing up from the roots. The wisdom of this procedure was evident. The elaborated sap is far richer in nutriment than the crude sap, and the woodpeckers knew more about the growth of trees than many human beings, so worked understandingly.
Each drill is made deep enough to hold about two drops of sap. The upper drills are the only ones to afford sap, which proves that it is certainly the elaborated sap flowing down from the leaves that the birds get.
I had read in works on ornithology that the woodpeckers tapped trees so that the sap would attract insects upon which they could feed. Also that the birds were after the soft bark, or cambium layer, for food.
While the woodpeckers do catch a fly now and then, it is evident, even to a careless observer, that it is the sap that is sought. I have seen them eat small pieces of the cambium layer, but I think they did so because the soft bark was soaked with sweet sap.
The three humming-birds made that little sunny glade in the forest as lively as a Mexican fandango. The two males were jealous of each other, and both birds seemed desperately in love with the demure maid. She attended strictly to business by drinking from the sap-buckets left unguarded by the red squirrel. The male hummers spent most of the time dancing in the air. They took turns in madly pursuing each other; the pursued never turned tail, but flew backward with a swiftness that was marvellous. The buzzing of their wings and their shrill cries furnished the music for the wild dance.