The midden is the animal's whole economy. A red squirrel cuts green conifer cones before they open, carries them to a central site and buries them in the accumulated debris of previous years. Inside that pile the humidity is high and stable, which prevents the cones from drying, opening and shedding seed, so the store stays viable for years rather than weeks.
Defence follows from concentration. A single point can be guarded, and the squirrel does so with a loud rattle call broadcast from perches around the territory boundary. Territories are held by individuals year-round rather than seasonally, and a vacant midden is a valuable inheritance that is contested quickly.
Long-term study of this species in the Yukon has produced some of the best data on wild mammal responses to variable food supply, including evidence that females increase reproductive output in anticipation of a spruce mast year, apparently cued before the seed itself is available.