Oaks and Wildlife
Oaks provide food, homes and shelter for animals, both large and small. Hundreds of vertebrates and thousands of insects are associated with the oak woodlands of California.
Many creatures make meals of acorns and oak leaves. Bears, muledeer, and about two dozen species of birds eat acorns. Scrub jay, magpies, wood ducks, wild turkeys, mountain quail, flickers and acorn woodpeckers all depend on oaks for food. Insects also feed on leaves, twigs, acorns, bark and wood of oak trees. Many of these six-legged creatures become meals themselves. Warblers, vireos and orioles are among the many insectivorous birds that feed in oaks.
Animals help oak trees by planting their seeds. Left above ground, acorns dry out and fail to grow. Squirrels and scrub jays hide acorns for later consumption. Well-hidden seeds are protected from freezing and drying. Many of these seeds grow into new trees.
Some animals depend on oaks to keep them safe from predators, while others use the trees as a home. Barn owls, wood ducks and many other cavity-nesting birds make their homes in oaks. In winter, ring-tail cats and squirrels sleep in oak tree cavities; in summer, squirrels make nests in oaks. Bees build beehives in hollowed-out oak trunks.
You may find galls on oaks, especially during summer and fall. These interesting formations are developed when the insect eggs (usually from a wasp) are inserted into oak leaves or branches. Oak tissue serves as an “insect nursery” by growing around the eggs. These coverings protect larval and adult forms. Most research shows that galls do not harm the oaks in any way.
Other creatures, such as spiders and centipedes, can be found on oak bark or hiding beneath it. Nematodes (tiny round worms) and earthworms live within the root system. Look in the leaf litter at the base of the tree to find slugs, snails, wood lice, beetles, millipedes, centipedes, caterpillars, earwigs, ants and spiders.
Oaks continue to be useful to wildlife even after they die. Salamanders, worms, snails, termites and ants live in decomposing logs and help turn wood into humus, which enriches soil.
An oak tree is truly a “community” of living organisms. Loss of oak habitat has a big impact on the survival of many types of wildlife.