Squirrels have got to be one of nature’s messiest animals. Today I parked my car near a long debris field under several Japanese Black Pines (Pinus thunbergii). The squirrels just throw the scales down after retrieving the seeds, making this huge mess on the ground below.

The squirrels that inhabit this parking lot are Eastern fox squirrels (Sciurus niger – top right) and are non-native to southern California. Its’ breeeding season for these squirrels. They tend to give birth twice a year, once in early spring and again in early fall with about 2-4 kits each time. These rodents and their little ones have caused a population boom in this parking lot, and they all eat the seeds found in these pinecones. There is a photo of the scales from the cone with the seeds stripped away (bottom right).

Different squirrels have different methods of peeling off the cone scales to get at the seeds. Here we have one pinecone stripped like a corn cob and another pinecone sliced in half to get to the seeds.   It looks like somebody got impatient and couldn’t wait to go one-by-one. The seeds are one of their primary food sources in this area. 

Pine trees produce both male and female pinecones, and naturally the female cones are the ones which produce the seeds, while the male pinecone produce pollen. There are two seeds on each scale and the squirrel must peel the scale of the cone to get at the seeds. In this picture (top right) you can see how a squirrel started to peel off the scales and for some reason never finished the snack. You can also see the two flat seeds at the base of the scale. Note that the scales are placed on the pinecone in a spiral formation. This arrangement allows for the even distribution of scales across the surface of the cone and provides plenty of room for the pinecone to open.

Pinecones respond to humidity in the air. When there is a high level of water in the air – like on cold or cloudy days- the female pinecones (bottom right) will close up. On hot and dry days they will open to expose the seeds to methods of dispersion like animals, wind or merely gravity. Besides hot summer days, fire is also another method of providing heat for pinecones to open and some species like the Jack pine (Pinus banksiana), and Table Mountain pine (Pinus pungens), require fire to open their cones.  This type of high-heat cone is called serotinous. Squirrels, however, don’t require the pinecone to open up in order to get their food. In fact, they seem to prefer gnawing at green pinecones since the seeds are still young and tender, and these little guys don’t seem to mind making a mess in the process of eating them!