The Wild Side of Mount Washington

by Julian P. Donahue

Here in the mountainous West, “Mount” Washington is a presumptuous appellation for what is no more than a pimple on the landscape. At a maximum elevation of 940 feet above sea level (at the water tanks near the Mt. Washington Elementary School), Mt. Washington is nearly three times higher than the highest point in the state of Florida (345 feet), but it is dwarfed by the San Gabriel Mountains that dominate our northern horizon, and absolutely humbled by California’s own Mt. McKinley, at 14,494 feet the highest point in the Lower 48.

Mt. Washington used to be much shorter in stature than it is now. So short, in fact, that it was nothing more than layers of sand and silt 2,000 feet deep on the bottom of an Upper Miocene sea between five and 10 million years ago! At that time the trees growing near the sea included oaks, sycamores, and maples (modern relatives of which are still here or nearby), plus trees characteristic of the present subtropical coastal lowlands of the southeastern United States, such as magnolia, bald cypress, and tupelo—and even avocados. A lot has changed since then. Calcium carbonate cemented the seabed into rock, and the rock layers were twisted, bent, folded, fractured, and thrust well above sea level, becoming part of what geologists now term the Puente Formation of rocks. These same rocks form the Elysian Hills to the south and the Montecito Hills/Debs Park to the east.

Weathering processes (wind, rain, gravity, plants, organic acids) wore down the top of Mt. Washington, sending some of it into adjacent valleys and turning the remaining surface into soil. People who live on a hillside lot, particularly those who experienced the 1969 Rainbow Canyon landslide, have first-hand knowledge that gravity is still hard at work trying to send Mt. Washington back into the sea from which it came.

The Mt. Washington rocks now at or near the surface of the soil are mostly sandstone (medium to coarse grained, light brown to gray in color), with some shale on the northwestern side of the hill (finer grained with silica, light gray in color). Fossil Foraminifera (calcium-shelled single-celled marine organisms), the source of chalk in many places, have been found here, and may in fact be the cause of the chalky deposits exposed by gardeners and excavators. Our sandstone is poorly cemented and can sometimes be fairly soft, particularly when wet, making it more prone to weathering and sliding. Few larger fossils have been found on Mt. Washington, but pieces of a baleen whale were found not too long ago between Quail and Pheasant Drives.

Zip 90065. Five miles from the heart of the nation’s second largest city and flanked by freeways on three sides, Mount Washington is a veritable wilderness compared to the more densely populated “flatland” areas that surround it. While level areas can be relatively biologically uniform and monotonous, hills have changes in elevation and topography, resulting in different angles of exposure to the sun, different drainages and moisture, different air movement patterns, different temperatures, and even different climates (called “microclimates” on a small, local scale). Gardeners on north-facing slopes may despair at growing plants that gardeners on south-facing slopes cultivate with ease—and vice versa.

Mt. Washington’s native habitats—yes, we still have some left—work on the same principle that gardeners have discovered. Habitats are usually defined by the plants that characterize them, and certain animals are associated with each major kind of habitat. (You expect to find bears in forests, for example, rather than in grasslands.) Because of Mt. Washington’s location midway between coast and desert, and because of our varied topography, we have not one plant community, or habitat, but a mosaic of no less than four different plant communities, sometimes distinct, sometimes blending from one to another: walnut woodlands, mixed chaparral, mixed chaparral-oak woodland transition, and coastal sage scrub. While some plants are more or less restricted to a single plant community, others occur in more than one. Our toyon and lemonadeberry, for example, are characteristic of both mixed chaparral-oak woodland transition and coastal sage scrub. Mt. Washington has some of the best remaining stands of Southern California black walnut, a tree that happens to prefer the same habitat as humans; this is another conflict where the final score has too often been Humans 1, Walnuts 0.

As Mt. Washington evolved from a weekend retreat to prime real estate for permanent homes, the natural environment has changed dramatically, not always for the worst. The bad news is that native trees and “brush” must be cleared for constructing a home. Even worse, at least for the wildlife, is that even more trees and brush must be cleared for great distances from streets and homes in order to protect structures from wildfires. The negative environmental impact of a single house thus extends hundreds of feet from the house itself. Animals that absolutely require chaparral, Mt. Washington’s most common kind of “brush” habitat, simply die out and disappear as their habitat is destroyed. Wrentits, chaparral birds unique to the west coast, have probably completely disappeared from Mt. Washington in the last decade, and other chaparral birds appear to be on the decline: Bewick’s wrens, house wrens, and spotted towhees. Birds that nest in tree cavities, such as western screech owls, Nuttall’s woodpeckers, and downy woodpeckers, decline as their trees are removed.

The relatively good news is that residents have planted an urban forest comprised of a remarkable variety of trees and shrubs. Most of these are “exotic” species (that is, not native to here), such as towering pines and deodars, that have greatly modified the original habitat, creating more variety in the original landscape that favors certain adaptable animals that like big trees and can tolerate people, such as great-horned owls, common ravens, red-shouldered hawks, and band-tailed pigeons. Other native birds that thrive in our suburban environment include northern mockingbirds, western scrub-jays, and house finches.

There are important reasons for the emphasis on “native” habitat. Plant species are simply not interchangeable. Our native animals have evolved in intimate association with our native plants. For example, most of our native insects will only eat native plants. Gardeners may heave a sigh of relief upon hearing this, but it is a life or death matter for the other native animals—insects lie at the bottom of the food chain that supports most other species of our native animals, from western fence lizards and spiders to many species of birds, striped skunks, and coyotes.

Mt. Washington’s most conspicuous native insects include at least 29 species of butterflies, including four species of swallowtail butterflies, gulf fritillaries, marine blues, and an occasional monarch. The exotic cabbage butterfly is on the wing every month of the year. Butterfly gardeners intentionally plant larval foodplants and nectar sources to encourage our native butterflies. Jerusalem crickets, fearsome but harmless subterranean dwellers, are well known to residents but quite astonishing to easterners, where these unique insects do not occur. Carpenter bees (often mistaken for the much less common bumblebee) and yellow jackets are conspicuous summer residents. Many other species of insects occur here, ranging from dragonflies and mayflies to true bugs and beetles, but most of them escape the notice of casual observers.

We also have our share of pest insects. Pests, whether insects or weeds, are usually exotic species that arrived here in the absence of the usual controls that kept their populations in check in their homeland (the “three Ps”: parasites, pathogens, and predators), and ours are no exception. They include pantry moths, houseflies, Argentine ants, and giant whiteflies. Honeybees are also exotic, widely propagated for their pollination services, but they become pests when they decide to set up a colony in your home or sting someone who is allergic to their venom. Although our mosquitoes are probably native species, they can be bothersome pests and can transmit serious diseases, including West Nile Virus, so residents must be vigilant about eliminating their breeding places.

Our “herptile” fauna (reptiles and amphibians) is quite depauperate. We have only two species of lizards, two species of snakes (none venomous), no turtles or tortoises, and one uncommon salamander. We have no native frogs because we have no natural water sources on the hill. The coast horned lizard (“horned toad”) used to occur here, but has apparently been extirpated. Horned lizards have declined elsewhere, perhaps in response to habitat destruction but, even more likely, because the exotic Argentine ant has eliminated the native ant species on which the horned lizard fed—alas, horned lizards apparently don’t like to eat Argentine ants, an abundant and bothersome pest.

In the bird department, however, Mt. Washington has an abundance of 108 species recorded so far, either on the ground or flying overhead. The seasonal rhythm of birds is rather dramatic and easily observed. Resident birds, these that breed here and occur throughout the year, in addition to those mentioned earlier, include mourning doves, California towhees, California thrashers (another brush-lover), phainopeplas, Anna’s and Allen’s hummingbirds, bushtits, and lesser goldfinches. (Exotic residents include house sparrows, rock doves or common “pigeons,” and European starlings. In recent years nutmeg mannikins, natives of Asia that breed in the Los Angeles River, have been regular visitors at Mt. Washington bird feeders. Yellow-chevroned parakeets may show up at any time, particularly to feed on the fruits of floss-silk trees.)

In the spring our summer residents arrive from the tropics; after breeding here they return south in the fall. The summer residents include the colorful hooded oriole and black-headed grosbeak, and the brood-parasitic brown-headed cowbird (it lays its eggs in the nests of other birds).

After the summer residents depart the winter visitors arrive: dapper white-crowned sparrows, the less common fox and Lincoln’s sparrows, dark-eyed juncos, cedar waxwings, hermit thrushes, and yellow-rumped warblers. Additional species sometime show up in the winter, including mountain chickadees, white-breasted nuthatches, and ruby-crowned kinglets. Northern flickers are more common at this time, but we have no definite evidence that they are year-round residents.

Finally, there are the passage migrants, birds that pass through the area in the spring and fall on their way to and from their breeding grounds. They are most colorful in the spring, when they are in full breeding plumage, and include several warblers (Townsend’s, Wilson’s, hermit, orange-crowned, Nashville, yellow, black-throated gray), rufous hummingbirds, Swainson’s thrush, Vaux’s and white-throated swifts, and several species of swallows (although cliff swallows remain to nest on bridges near the Los Angeles River).

Mammals complete our inventory of Mt. Washington animals, and we have some nice ones—and some not so nice. Once again, the not-so-nice ones are exotic, introduced pest species: the house mouse, brown (Norway) and roof (black) rats, fox squirrels, and opossums. The omnivorous opossum, native the eastern U.S., was intentionally introduced to California in 1910, perhaps as an alternative source of food. The fox squirrel, also native to the eastern U.S., was also introduced intentionally, perhaps because easterners missed its presence in park settings. Fox squirrels first appeared in Mt. Washington in the mid 1970s, most likely spreading from adjacent populations in the San Fernando Valley, and since then has become a resident pest, although a cute one: besides eating bird eggs and cultivated fruit it chews through and damages cable and telephone wires.

Some of our native mammals can be occasional pests (a pest is simply an animal or plant that competes for something that we humans want). Broad-footed moles and Botta’s Pocket Gophers are beneficial as natural aerators of the soil, but when they perform these activities in our gardens they become pests. Striped skunks are treasured by some, while others do not enjoy it when a skunk decides to take up residence in their basement. Dog owners also become curiously upset when their canine tangles with Mr. Skunk.

Raccoons, robust creatures with a “bandit” mask, are delightful residents of Mt. Washington. When these inquisitive and intelligent creatures decide to raid a koi pond or wash muddy objects in a swimming pool, however, their nocturnal visits may not be welcomed with great relish. Rabbits and California ground squirrels are curiously absent from Mt. Washington—perhaps feral cats and coyotes have eliminated them.

Coyotes are the top predator on Mt. Washington, and their presence demonstrates how close to nature we really are. They cling to existence in our parks and wilder canyons, where they feed mostly on our abundant rodent population (rats, mice, gophers). But the “lost dog” and “lost cat” posters that spring up on neighborhood utility poles are sad reminders that coyotes also occasionally snatch unwary and unguarded pets. The eerie and chilling howls of coyotes at night give one the sense of truly living in a wilderness, while seeing one of these nimble wild dogs in the daylight is a startling experience that triggers mixed emotions: delight at seeing a truly wild creature, fear that it will attack something we cherish, wonder about what it will do next, a sense of relief when it disappears harmlessly into the brush, and amazement that we live in the city of Los Angeles and have experiences like this.

With knowledge about our natural environment comes the ability to understand how its complexity enriches our lives and enhances the reason many of us moved to Mount Washington in the first place: to be close to nature. How well we accept our role as stewards of the environment will determine how much of Mount Washington’s natural world we retain.

Sources:
Lamar, Donald L. 1970. Geology of the Elysian Park-Repetto Hills Area, Los Angeles County, California. Calif. Div. Mines & Geology, Special Report 101. 45 p., 2 maps.

Mount, Jack D. 1969. Sedimentologic and paleoenvironment study of a portion of the Puente Formation, Los Angeles, California. Bull. Southern Calif. Paleontological Soc. 1(8): 1-6.

Mount, Jack D. 1970. A late Miocene flora from the Puente formation of Southern California [abstract]. Bull. Southern Calif. Paleontological Soc. 2(9): 11.

Rundel , Philip W. and Robert Gustafson. 2005. Introduction to the Plant Life of Southern California: Coast to Foothills. California Natural History Guides 85. Berkeley: University of California Press.
Topographic map of Mount Washington: http://www.topozone.com