[Wikipedia] Ecology: Pinus flexilis is an important source of food for several species, including red squirrels and Clark's nutcrackers, the latter being an important distributor of seeds.[14][7] There is evidence that limber pines co-evolved with Clark's nutcrackers, which are the primary dispersers of the seeds.[15][14][16] In a relic, low elevation population, seeds are also dispersed by small rodents.[17] American black bears and grizzly bears may raid squirrel caches for limber pine nuts.[7] Squirrels, Northern flickers, and mountain bluebirds often nest in the trees. There is some evidence that P. flexilis has a symbiotic relationship with nitrogen-fixing bacteria that inhabit the needles.[18] (link added by Mary Ann Machi)