Red squirrels occupy northern boreal coniferous forests abundant with conifer seeds, fungi, and interlocking canopies. This limits them to mountain ranges on the southern and eastern boundaries of their range. Red squirrels differ from other tree squirrels by their deep reddish color, territorial behavior, and their smaller body size. They are less than 30% the size of grey squirrels (Sciurus carolinensis).Red squirrels are primarily diurnal, but on occasion exhibit nocturnal activity. During the spring and summer they are most active in the morning and afternoon, but as fall approaches they become highly active all day in preparation for the food shortages associated with winter. In the winter, red squirrels peak their activity around midday to take advantage of warmer temperatures. Throughout most of their range, and especially in coniferous forests, both male and female squirrels vigorously defend exclusive territories from competitors. Red squirrels have well-developed and extremely acute senses of smell, sight, and hearing. They are well known for their ability to communicate by calls. Red squirrels are primarily granivorous, but they are also opportunistic omnivores in the absence of mast foods. Primary diet items vary with habitat and include the seeds of conifers and other tree types.
Source: Tamiasciurus hudsonicus Red Squirrel, Animal Diversity Web, University of Michigan Museum of Zoology