Naturalist Notes

Flora and fauna to watch for this fall.

Acorn Woodpecker

Acorn Woodpecker

Red-capped, clown-faced flocks are easy to spot in oak woodlands. They live in big noisy groups; listen for their raucous, laugh-like calls. In fall they get busy, drilling holes and stashing acorns in trees, fence posts, and other wooden structures. A single tree may hold thousands of hidden morsels, serving as a communal food pantry through winter. The birds carefully tend stored food, making sure acorns are wedged tightly so other animals can’t snatch. They also practice cooperative breeding with all the adults working together to raise the young from a single nest. Add sightings of Melanerpes formicivorus to iNaturalist.

Bigleaf Maple

Maple tree leaves in fall colors

One of our few native trees to offer autumnal color, the deciduous leaves of bigleaf maple carpet woodland floors in shades of yellow and orange during the fall. Having the largest leaves of any maple, leaf widths of nearly two feet are possible but 6-12 inches are more common. Capable of crown-sprouting, these trees can quickly regenerate after fire. Although the sugar content is comparable, the taste differs from common maple syrup and therefore this species isn’t typically tapped for its sugary sap. Add sightings of Acer macrophyllum to iNaturalist.

California Black Oak

Black oak leaves, colorful in fall

Native oaks are woven deep into the life of California ecosystems. Owls, woodpeckers, and squirrels nest in the safety of oaks. Many wild mammals and birds survive the winter thanks to nutritious acorns. Black oak acorns are a favorite wild forage, and native Americans preferred black oak acorns when making meal. Black oaks also offer a luxurious display of fall color uncommon to the Bay area’s native trees. With thick bark, and a rich supply of nutrients stored in their roots, oaks have adapted to survive wildfire. Sadly, they are not resistant to sudden oak death, a pathogen exacerbated by climate change, that is claiming the lives of thousands of oaks across the state. Add your sightings of Quercus kelloggii to iNaturalist.

Columbian Black-tailed Deer

Columbian black-tailed deer standing in green grass

A subspecies of the mule deer (whose name refers to their large ears), Columbian black-tailed deer are especially common in neighborhoods during the dry months of fall where they take advantage of irrigated vegetation, providing humans with a front row seat to the breeding season or “rut”. In October or November males chase females and perform loud displays as they vie for dominance among other males by thrashing their antlers in shrubs and occasionally engaging in heated sparring. The victor will ultimately mate with the females in that area over the course of a couple weeks. This synchronized breeding results in each population’s fawns all being born within a day or two, ultimately minimizing the chances of predation on any individual fawn while they are small and vulnerable. Add sightings of Falco peregrinus to iNaturalist.

Pacific Common Seal

Harbor seals hauled out on rocks

Also known as Pacific harbor seals, these marine mammals have pretty spotted coats in a range of shades from silver to brown. They spend half their time in water, diving for seafood: sole, flounder, hake, cod, herring, or squid. Safe in the surf, they often stop to bob and fix curious eyes on shore dwellers. When they haul out on land, they prefer to be left alone, snoozing in groups as they recuperate from swimming and foraging. Although rare, mothers will sometimes leave a pup on the shore when they move off in search of a meal. If you spot a solitary youngster, leave the pup alone–mom will soon return. Any disturbance reduces the young one’s chance of survival. Add sightings Phoca vitulina to iNaturalist.

Pallid Bat

Pallid bats hanging in a cave

Primarily insectivores, pallid bats eat up to half their body weight in bugs each night, eating as they fly or even landing on the ground and chasing down prey on all fours. Antrozous pallidus uses echolocation much less than most other bats and often hunts by sight or by using their large ears to listen for the rustling of insect wings. In desert climes they have adapted to feed on cactus nectar, helping seasonal pollination. Add sightings of Antrozous pallidus to iNaturalist.

Pacific Poison Oak

Close up of shiny poison oak leaves

This common native plant, a member of the cashew family, defends itself against infection with an oily sap that causes a severe allergic reaction in humans. As problematic as the irritating chemical urushiol can be for people other animals, including deer and squirrels, love to eat the leaves. Squirrels, foxes, and woodrats nest in poison oak, and over fifty species of birds feed on the seasonal berries. Open space visitors should avoid contact with this plant, but they can feast their eyes on vibrant colors when the leaves turn in fall. Add sightings of Toxicodendron diversilobum to iNaturalist.

Peregrine Falcom

Peregrine falcon in flight

The name peregrine comes from the Latin peregrinus, “wanderer”, and true to its name, this long-distance migrant is also the world’s most widespread raptor. Northern breeders move south along the Pacific Flyway following the fall migrations of their prey species. When hunting, peregrines turn into feathered bullets, plummeting from great heights and reaching speeds of 250mph – making them the fastest animal on earth. Watch for their strong flight on pointed wings, cruising over wetlands and swooping down on flocks of ducks and shorebirds. Add sightings of Falco peregrinus to iNaturalist.

Sonoma Chipmunk

Sonoma chipmunk sitting on a post

This adorable rodent, marked by five black longitudinal stripes, is found in chaparral and forested areas of Marin and Sonoma counties. In fall they get busy, foraging during the day for seeds, fruits, and insects, stuffing their cheek pouches. They carry the treats back to snug underground dens, building a food cache to sustain them through winter hibernation. You can spot Neotamias sonomae perching on stumps, low tree limbs, and rocks, munching and keeping a watchful eye out for intruders. Add sightings of Neotamias sonomae to iNaturalist.

Western Forest Scorpion

Scorpion lurking in leaf debris

With the coming of fall rains, after spending the dry season underground, our most common scorpion moves to the soil’s surface where it spends the day hiding under logs or rocks. Active at night, these small arachnids hunt a variety of invertebrates which they immobilize with their pincers, sometimes bringing their tail over their head to insert their sharp stinger into the prey. Just below the stinger is the venom bulb. When it’s time to mate they engage in a complex courtship which involves the male and female waltzing face to face and pincers to pincers. Shy and nonaggressive, these woodland scorpions have a moderately painful sting but prefer to avoid humans. Add sightings of Uroctonus mordax to iNaturalist.