According to my dictionary, midden means 1) a refuse heap or 2) a small pile (seeds, bones, leaves for example) gathered by a rodent. A chickaree, or Douglas’ tree squirrel, (Tamiasciurus douglasii) makes both types of midden.
Fall is harvest time for the chickaree. Walking through forests during the fall I hear the constant chatter of this dynamic little mammal as it gathers conifer cones, acorns and other nuts, and mushrooms for the winter. These are gathered and tucked away in tree hollows, under logs or in rock crevices for future use during the winter. These small piles of food are called middens.
Chickarees have a very small territory or home ground, often consisting of only a few trees. The home territory of a chickaree is marked by a refuse heap midden. A chickaree will sit on a log, stump or hillock and tear the scales off of conifer cones to reach the seeds. Starting at the bottom of the cone, it will remove the scales one at a time until only the cone core remains. Returning to the same spot to eat, the chickaree eventually builds up a large accumulation of cone scales over a period of several years. This midden, or refuse pile, can reach several square yards in area and often begins to decompose beneath the top layers of fresh scales.
The refuse midden can also become a “storage” midden. Chickarees will hide their winter cache in the midden heap of old cone scales or scatter cones on the top of the midden heap thus creating a midden in or on a midden. (Could not resist!)
Chickarees also create smaller middens or refuse piles when they feast on cones away from their primary midden. Even without hearing the scolding notes and calls of the chickaree, sighting a cone scale midden alerts one to the presence of chickarees.
These middens and chickaree pictures were taken near the Lower Campground at Ash Creek and near the Merrill Campground at Eagle Lake, both in Lassen County CA, and near Manzanita Lake in Lassen Volcanic National Park.