Fungi in the winter diets of northern flying squirrels and red squirrels in the boreal mixedwood forest of northeastern Alberta

Abstract

Gut contents of 138 northern flying squirrels (Glaucomys sabrinus) and 75 red squirrels (Tamiasciurus hudsonicus), which had been trapped from November to February in the boreal forest of northeastern Alberta, were examined to determine which fungi were consumed as food during the winter months in this habitat. Spores of epigeous Boletales, Russulaceae, and Cortinariaceae were most frequent and numerous. Hypogeous ascomycetes (unidentified species of Elaphomyces and Tuber) and basidiomycetes (unidentified species of Gautieria, Hymenogaster, Hysterangium, and Rhizopogon) were sometimes present in substantial amounts but were not as frequent as the remains of epigeous fungi. Guts sometimes contained remains of the tough or carbonaceous sporocarps of unidentified species of the Hymenochaetales, Diatrypaceae, Xylariaceae, and Bankeraceae. The spores of some rust fungi (e.g., Phragmidium fusiforme) along with the conidia (e.g., Helicoma sp.) and ascospores of microfungi (e.g., Sordariaceae) were also detected. Lichen tissues were absent, and this contrasts with previous suggestions that lichens are a winter food of sciurids in regions with substantial snowfall. A parallel analysis of 110 faecal pellets from northern flying squirrels collected in the same area from June to August confirms that fungi are important in its summer diet.Key words: Glaucomys sabrinus, Tamiasciurus hudsonicus, fungi, mycophagy, Sciuridae.