The Relations of Breeding Yellow-Bellied Sapsuckers to Wounded Birches and Other Trees

Abstract

WHILE I was studying Yellow-bellied Sapsuckers (Sphyrapicus varius) on their breeding grounds in central New Hampshire (Kilham, 1953, 1956, 1962), it became apparent to me that birch trees (Betula) were often used as sources of sap when young were in the nest or had emerged to become part of a family group. The species involved were the white (B. papyrifera), yellow (B. lutea, var. alleghaniensis), and gray (B. populifolia) birches. Sapsuckers also feed on a variety of other trees (McAtee, 1911). Regardless of the trees utilized, however, it is not always obvious why they concentrate on a single tree here and there, leaving many others untouched. In the summers of 1962 and 1963, I found three areas well suited to study of this problem. One, Area A, centered on groups of white birches growing along a dirt road (Figure 1), where snow plows and undercutting of banks had produced both injuries and weakening. This area was the territory of Pair A. Areas B and C were occupied by seven other pairs of sapsuckers and consisted of woodlands where hundreds of unwanted or weed trees had been girdled as part of a forestry management program.