Warm days, gold and crimson foliage, and migratory animals mark fall in Muir Woods. Sonoma chipmunks prepare for hibernation by foraging through the woods for seeds, nuts, and berries, then storing the food in small holes covered with dirt and leaves. Throughout the season, convergent ladybugs cluster on understory plants after flying here in early summer to escape inland heat; near the creek they gather in dense clusters, conserve body heat, and emit a foul smelling odor to ward off predators while they rest. In early spring they wake up, mate, and return inland to lay their eggs. Fall foliage drops to the canyon floor like raindrops as poison oak turns flaming red, maple leaves change from green to mustard, and California bay-laurel leaves turn lemon yellow. These leaves also provide nutrients for the forest and its animals: big-leaf maples nourish black-tailed deer with calcium and potassium, water striders feed on decomposing leaves in Redwood Creek, and migratory and resident birds fuel up on ripened poison oak, huckleberry fruits, tan oak acorns, and cow parsnip seeds. October marks the end of the dry season, when fires are a natural occurrence in the forest; they release nutrients tied up in the soil, burn weak trees that compete for light in the canopy, clear piled up debris in the understory, kill insects or disease that can harm a forest, and create the bare mineral soil needed for redwood seeds to grow and for new growth to regenerate the forest. In September, ladybugs cluster, fall color is at its height, and the year is warmest; in October, berries, buckeyes, and acorns ripen and fire season arrives; in November, migrating birds are active and the rainy season begins.