From Our President: Oak Trees Play Important Roles
Posted on Tuesday, July 1st, 2014
We have several large Oregon White Oaks on our property. During midsummer, as the high sun filters through the leaf canopy, the oaks create cool, shady spots where we can sit and enjoy the summer afternoons. These trees are always filled with birds. The oaks provide good nest sites, and we have seen Purple Finches, Cedar Waxwings, American Robins, and Warbling Vireos nesting in them. One year, we found a juvenile waxwing on the ground under an oak tree. It tried to get up on the fence but could not yet fly, and it was vulnerable on the ground. We put it up on a lower branch of the oak tree and the parents continued to feed it; we hope it survived.
Many other birds forage in the oaks throughout the year. The chickadees and mixed flocks of kinglets and warblers move through the trees as they migrate, and the chickadees also gather moss for their nests from the oak limbs. We have a pair of Black-capped Chickadees in a nest box this year, and the adults feed their young every day with insects gleaned from the oaks. Of course, the acorns are great food for jays, Band-tailed Pigeons, and woodpeckers.
A pair of Downy Woodpeckers have a nest in an old ash snag nearby, so we often hear a tap-tap-tap as the birds forage for insects in the oaks. These large trees host successive hatchings of various insects that the birds in our area depend on for food. One June morning, I saw swallows sweeping under the oaks right off our deck. I went outside to see what they were after and watched as small green larvae dropped on tiny filaments out of the oak branches. The swallows were capturing the larvae as they dropped, and the birds systematically worked the area under the trees while the insects tried to fulfill their life cycle.
Before European American settlement, oak savannas were a primary ecosystem in the Willamette Valley. The loss of the big oak trees to agriculture and human habitation and the encroachment of Douglas-fir trees has harmed the survival of many bird species that depend on the oaks for year-round food and shelter. Declines in numbers of Lewis’s Woodpeckers and White-breasted Nuthatches have been linked to the loss of oak woodland habitat. We consider our big oaks an important part of the neighborhood, which would be drastically changed if the oaks were not there. The trees are beautiful as well as essential for the ecosystem. I think of them as old friends or family members who need my care and attention, but who will also (I hope) outlive me!