Autumn on the Yosemite Valley floor runs on acorns. The California black oak, Quercus kelloggii, the Kellogg oak of the park's early naturalists, belongs to the lower montane forest the Park Service maps across the Valley and along the Wawona and Big Oak Flat Roads. The oaks are turning now, and the crop under them draws the bears and the birds.

The Park Service lists acorns as the black bear's favored fall food and says bears weigh the most in fall, when they gorge on them. Large males that summer in the backcountry come down to the Valley, Wawona and El Portal for the crop, so there are more bears near people in October than in July. The park's conditions page, updated September 25, says bears remain active in all areas of the park. The bear safety guide covers what that means for food storage at a campsite or a parked car.

The birds work the same trees. Acorn woodpeckers keep granary trees, dead pines drilled with hundreds of holes, each fitted with an acorn. Jays bury theirs one at a time in the ground, and that habit is part of why there are oaks at all: an acorn cached and forgotten is an acorn planted. The meat is bitter with tannin, which is why the Miwok leached acorn meal with water before cooking it, a practice the park's naturalist described step by step in October 1931.

The crop is not the same every year. Oaks bear heavily in some autumns and lightly in others, and the park's naturalists wrote down which kind of year each one was.

A black oak in a Valley meadow. Photo: Brocken Inaglory / Wikimedia Commons (CC BY-SA 4.0)

From the naturalists' notebooks

In September 1931 the ranger-naturalist Enid Michael walked the oak groves on the north side of the Valley and recorded a poor year: "There is a scanty crop of acorns on the Kellogg oaks this year, and no crop at all on the Chrysolepis oaks." The Chrysolepis oak is the canyon live oak, the evergreen one on the talus. Yosemite Nature Notes, Vol. 10 No. 9

A year later, in October 1932, Assistant Park Naturalist M. E. Beatty found the season in full swing: "our blue-fronted jays and woodpeckers are busy storing acorns for winter use. Bears are foraging for every available source of food supply." The blue-fronted jay is the Steller's jay. Vol. 11 No. 10

And in October 1939 Ranger-Naturalist Lowell Adams, writing about jays raiding the acorn stores of the Paiute basket maker Tabuce, drew the conclusion that still holds: "many of the acorns hidden by the jays are never found again and thus are allowed to sprout and grow." Vol. 18 No. 10

Ninety years on, the cast is the same: the same oaks, the same jays and woodpeckers, the same bears coming down to the Valley for the same food.

Also in season

The leaves are going too. In October 1932 Beatty recorded the black oaks "changing to yellows and browns," with the golden yellows "best represented in the quaking" aspen. The fall guide has where the color runs and when it usually peaks.

The bears in the oaks are the reason fall is the season to watch for them from a distance, and never to let one find a human meal. The wildlife viewing guide lists where and when to look, and how far back to stand.

Before you go

Glacier Point Road has been closed since September 23 for the Dome Fire, with no reopening date; the Four Mile and Panorama Trails remain open to hikers, as the Glacier Point guide explains. Smoke settles overnight in Wawona and the Valley, so check fire.airnow.gov before you drive in. The rest of October's closings are in the October edition.

Forwarded this? The letter is free at thetalusfieldjournal.com/newsletter. Know someone who would want it? Forward it.

Store the food, even in the Valley. Back next Sunday.