When fall arrives to coniferous forests throughout the western US, several species of pine, spruce, and fir potentially produce cones.
Engelmann spruce cones
I say potentially because many species don’t produce cones every year, or in some years they produce thousands of cones and in other years just a few cones. This presents a problem if you depend on cones as a food source as do many tree squirrel species and birds such as crossbills. Such an unpredictable food resource means that you have to make the most of what you get when you get it. Red squirrels are really good at this!
Red squirrels (Tamiasciurus hudsonicus) and Douglas squirrels (Tamiasciurus douglasii) are unique among squirrels because of their food storing behavior known as larder hoarding. These squirrels feed on cones in centralized locations where the cone scales build up into heaping piles.
red squirrel midden scale pile made primarily of ponderosa pine scales
These centralized scale piles are known as middens and basically act as refrigerators for squirrel food. Squirrels dig pits into the midden scale pile and ground surrounding the pile and store young cones that they have clipped from surrounding trees in these pits. The cool, moist microclimate of the scale pile prevents cones from opening up. This way, the seeds inside each cone are safely stored for later consumption.
Red squirrels are very particular about how each cone is placed into the midden, and this makes sense since squirrels are dependent on their cone stores for overwinter survival because they don’t
cached Douglas-fir cones carefully arranged by a red squirrel
hibernate. That’s why, throughout their range, you can observe red squirrels busily clipping cones this time of year and dashing off with them to store in their middens. Watch your head though – some cones, such as those from southwestern white pine trees (Pinus strobiformis), are quite large! When they crash to the forest floor it sounds like somebody slammed a car door shut.
For young red squirrels setting off on their own, the limited supply of cones both spatially and temporally imposes a limit on how long they can spend searching for a place to call home. They need to find a place to live in time to store enough cones before
Juvenile male red squirrel has found a good spot - even though the cones here (southwestern white pine) are as big as he is!
the cones dry out on the trees, open up, and lose all of their seeds. Once a good spot is found, young squirrels get busy clipping and storing. If they have chosen wisely, they will have enough food to survive the winter and a chance to reproduce the following year.
