Midden is an old word for garbage dump. Squirrel midden contains the remnants of pine cones and shells left behind as the squirrel seeks out the seeds enclosed in them. Sometimes squirrels use the middens themselves to burrow in and hide more food.
Sitting on their favorite branch, stump, or wherever, they pull the outside bits of the cone off, letting them fall to the ground below, and eat the seeds inside. The piles of left-over pine cone bits below are often easily found around a fir tree forest floor. They can get pretty big.
Squirrels also hide or store their food for the winter. They do not always remember where they have hidden some of the pine cones. Often you will see holes around the midden where they may or may not have had a successful search. Some of the forgotten ones may grow into pine trees.
Why store food? Squirrels do not hibernate, they remain active through out the winter. The extra caches of food can come in handy when supplies are low during the cold months.
It’s fun to walk along the trail and see “midden” left by the squirrels as they forage for the seeds in the pine cones. If you look closely, you can find many of these heaps of midden along the trails that you had never noticed before.