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

Gut contents of 138 northern flying squirrels (Glaucomys sabrinus) and 75 r ed squirrels (Tamiasciurus hudsonicus), which had been trapped from Novembe r to February in the boreal forest of northeastern Alberta, were examined t o determine which fungi were consumed as food during the winter months in t his habitat. Spores of epigeous Boletales, Russulaceae, and Cortinariaceae were most frequent and numerous. Hypogeous ascomycetes (unidentified specie s of Elaphomyces and Tuber) and basidiomycetes (unidentified species of Gau tieria, 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 sporoc arps of unidentified species of the Hymenochaetales, Diatrypaceae, Xylariac eae, and Bankeraceae. The spores of some rust fungi (e.g., Phragmidium fusi forme) along with the conidia (e.g., Helicoma sp.) and ascospores of microf ungi (e.g., Sordariaceae) were also detected. Lichen tissues were absent, a nd this contrasts with previous suggestions that lichens are a winter food of sciurids in regions with substantial snowfall. A parallel analysis of 11 0 faecal pellets from northern flying squirrels collected in the same area from June to August confirms that fungi are important in its summer diet.