Observations were made on Tamiasciurus hudsonicus in mature Picea glauca forest during 2 years of cone crop failure. For the first winter an adequate supply of old Spruce cones cached in previous years was available. The second crop failure brought about a 67% drop in the squirrel population, the remaining squirrels feeding primarily on Spruce buds during the winter. Spruce seed, when available, is the major constituent of the diet, while in its absence mushrooms are utilized in summer and Spruce buds in winter. Feeding trials with captive squirrels showed that about 194 old Spruce cones per day were necessary to sustain one squirrel-ca. 35% more than cones from the current year's crop. Three squirrels survived for 8 days on a diet of White Spruce buds only. Excavation of middens revealed up to 8500 old, cached cones per midden, despite a crop failure. Squirrels may cut and cache 12, 000-16, 000 cones in a normal to heavy cone crop year, the excess accruing annually, eventually creating a supply sufficient to maintain the squirrels through a winter following a cone crop failure. KEYWORDS: Picea glauca injury, squirrels, Squirrels feeding habits.