Late post, I know, but one of my field guides for the Pacific Northwest describes a symbiotic triangle of sorts between squirrels, fungi, and conifers. The fungi form a mycorrhizal relationship with the tree, with carbohydrates flowing from the tree to the fungus and water and soil minerals the fungus to the tree. Squirrels enter the equation by spreading seeds/spores in exchange for food. While they do eat many of the pine cones that they bury in caches, the ones they forget about are much more likely to germinate than those that never got buried in the first place. Squirrels cache mushrooms, too, getting spores on themselves in the process. These spores inevitably fall off during the squirrel’s travels, allowing some fungal spores to germinate far from their parent.