Abstract
In late June 2020 in western Montana we observed up to 10 Cedar Waxwings (Bombycilla cedrorum) feeding on tree sap at Red-naped Sapsucker (Sphyrapicus nuchalis) sap wells excavated on 2 limbs of a Water Birch (Betula occidentalis). These observations constitute (a) the 1st report of waxwings feeding at sap wells created by sapsuckers of any species; (b) the 1st report of waxwings feeding on tree sap in early summer; and (c) the 1st report of the consumption of birch sap by this waxwing species. The Cedar Waxwings may have sought tree sap because of the limited availability of early-summer sugary fruits at the time of our observations in combination with the presence of new clusters of sap wells created by at least 1 pair of sapsuckers near where the waxwings were beginning to breed. The prevalent sugars in birch sap (glucose, fructose) are also those most efficiently assimilated by Cedar Waxwings and may have contributed in attracting the waxwings to the sapsucker wells.
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