Your Interpretive Guide to the
Monrovia Hillside
wilderness Preserve
This interpretive guide to the Monrovia Hillside Wilderness Preserve was produced to educate the citizens of
Monrovia on the value of this special resource. Whatever need the preserve fills for you, hopefully, someday
you will want to know more about this ecosystem. This pamphlet is intended to be an introduction to the life in
the preserve. I am sure readers will be overwhelmed by the amount of information contained herein. However,
let me assure you that contributors who have written these essays started out just like you, having more desire
than knowledge. Only through time, observation, and study did they achieve their current status. You will find at
the end of this pamphlet a list of reference materials we recommend for additional study. For those individuals
wishing to learn more about this resource, we suggest starting with botany and plant identification. Beginning
with the plants is logical since the plants are the foundation for all other life, and they are the most accessible.
If you set a goal of a number of plant identifications at each visit, it won’t be long before you learn the plant
communities. From there you can graduate to birds, insects, and or reptiles.
You can spend the rest of your life exploring and never see everything, but I assure you each visit will be a
rewarding experience to both mind and body.
Glen Owens
873 Ridgeside DrIVE
< Cover photo: Cliff McLean
Map by Lin Kroll
by Bruce Carter, PhD
The Monrovia Hillside Wilderness Preserve is part of the San Gabriel Mountains,
an east-west trending range bounded on the north by the San Andreas Fault that
separates the Pacific and North American plates. Disruption within the broad plate
boundary zone has produced many other faults within and along the boundaries
of the San Gabriel Mountains. Originating to the south around the latitude of
San Diego, this fragment of ancient continental crust was faulted away from its
surroundings, displaced about 110 miles northward and rotated about 90 degrees
into its present position over the past ten to twenty million years.
The preserve occupies an unusual position intermediate between the high rugged
mountains on the north and the lower flatter outwash plain on the south. Both to the
west in Sierra Madre and beyond and farther east in Azusa and beyond, the steep
mountain front mostly rises abruptly above a single fault break separating it from
the valleys underlain by deposits of alluvium eroded from the adjacent mountains.
In contrast to the single fault elsewhere, the preserve is an area in which several
faults intersect.
The faults impacting the preserve
(which is shown in the center):
San Gabriel (A)
Sierra Madre (B)
Raymond Hill (C)
Clamshell-Sawpit (D)
Cucamonga (E)
The San Gabriel fault (an old trace of the San Andreas) runs along the East and
West forks of the San Gabriel River within the mountains. Within the preserve
the Sierra Madre, Raymond Hill and Clamshell-Sawpit faults each have multiple
branches, and together produce a broad zone of crushed and altered rocks that
weather to form an area of relatively low topographic relief intermediate between
the plain to the south and the mountains to the north. At depth, local fault breaks
block the subsurface percolation of groundwater, resulting in a number of springs
and forming a relatively well-watered area that supports a diverse vegetation
assemblage in the preserve.
Ancient rocks underlying most of the area consist of Mesozoic (about 100 million
years old) quartz diorite and a variety of older metamorphic rocks. The quartz
diorite is generally grey (weathering to more brown) and is thoroughly fractured
and altered particularly along fault zones. Metamorphic rocks include biotite gneiss
that is foliated and commonly layered and is interlayered with masses of light
colored gneissic granitic rock.
Sedimentary deposits of sand and gravel washed out of the mountains to the
north lie above the older basement rocks. These include coarse alluvium in
modern stream courses like Monrovia and Big Santa Anita Canyons as well as
older deposits uplifted above the modern stream courses. These deposits include
quaternary terrace deposits immediately above modern stream courses and the older
more reddish clay-bearing rocks of the San Dimas formation. These deposits can be
seen overlying older basement rocks to form a generally flat surface to the east in
Bradbury mesa.
Older stream terrace deposits occur perched above streambeds, at the mouths
of some of the larger canyons and less commonly on ridge tops. They are
unconsolidated massive to poorly bedded deposits with boulders and cobbles in a
sandy-pebbly matrix. Boulders are rounded, mostly fresh and locally reach eight to
ten feet in length, particularly in Monrovia and Sawpit Canyons.
Plant Communities and Flora
by Mickey Long
What is a “Plant Community”?
As you walk along the Lower Clamshell Road you are surrounded by
native vegetation that can be subdivided into local habitat based plant
communities. Botanists define these natural communities by identifying
specific plants that occur with each other due to similar adaptations to soil
types, topography, and precipitation. In other words, plants that like the
same conditions occur together.
Heart-leaved penstemon
Photo: Cliff McLean
The Monrovia hillsides in their natural condition represent high quality
vegetation and wildlife communities, and are dominated primarily by
four natural plant communities: chaparral, southern oak woodland,
coastal sage scrub and riparian. The chaparral is formed of a mix of
woody shrubs reaching twelve to fifteen feet in height and often forms
impenetrable thickets. Common plants here include laurel sumac
(Malosma laurina), toyon (Heteromeles arbutifolia), mountain mahogany
(Cercocarpus betuloides), elderberry (Sambucus nigra subsp. caerulea),
chamise (Adenostoma fasciculatum), scrub oak (Quercus berberidifolia),
hoary-leaf ceanothus (Ceanothus crassifolius), chaparral honeysuckle
(Lonicera subspicata), Whipple yucca (Hesperoyucca whipplei), heartleaved penstemon (Keckiella cordifolia), white sage (Salvia apiana), and
abundant poison oak (Toxicodendron diversilobum).
Stop and look down into Ruby Canyon and notice the lush and dense,
cover of trees and shrubs in the canyon bottom and on the northeast-facing
slope. Southern oak woodland and riparian communities dominate here
with stands of coast live oak (Quercus agrifolia), canyon or golden-cup
oak (Q. chrysolepis), and individual trees and small stands of western
sycamore (Platanus racemosa) and big-leaf maple (Acer macrophyllum)
in the upper portion of Ruby Canyon. Also common are hillside
gooseberry (Ribes californicum var. hesperidium), wild cucumber (Marah
macrocarpus) and dense poison oak.
Now turn to face the north and notice that the drier south-facing hillsides
above you have a less dense cover of more scattered shrubs. These
shrubs must be more drought tolerant. This is because the south-facing
slopes receive more direct sun and water evaporates more rapidly. The
deep canyons and north-facing slopes retain their moisture and support
the heavy cover of more moisture loving species. These moist, shaded
canyons have high value for resident and migrating wildlife such a birds,
in supplying cover, feeding and resting areas.
Poison oak
Photo: Cliff McLean
Along the walk, there are occasional openings on drier, more exposed
ridge lines and south-facing slopes, that support the scattered plants
that make up the coastal sage scrub community especially California
sagebrush, (Artemisia californica), flat-topped buckwheat (Eriogonum
fasciculatum), deerweed (Acmispon glaber) and lemonade berry (Rhus
integrifolia). These species, particularly buckwheat, deerweed, and black
sage (Salvia mellifera) become dominants as “pioneer plants” in sites
recovering from grading on old firebreaks or after fires.
Many introduced plantings and individual “volunteers” along your route
can be traced to an old nursery established in the next drainage to the
east or are remnants of earlier canyon establishments. There is a fairly
large stand of invasive non-native tree of heaven (Ailanthus altissima)
on the northern slope near the road crossing and numerous introduced
plantings [e.g., Spanish broom (Spartium junceum), century plant (Agave
americana) and jasmine (Jasminum mesnyi)].
Bush monkeyflower
Photo: Cliff McLean
Arabian pea
Photo: Cliff McLean
Other plants fairly commonly observed along the route within the other
plant communities include coastal wood fern (Dryopteris arguta), coffee
fern (Pellaea andromedifolia), foothill needlegrass (Nasella lepida—
few), melic grass (Melica imperfecta), bush monkeyflower (Mimulus
aurantiacus), four lupine species (Lupinus bicolor, L. truncatus, L.
hirsutissimus, L. sparsiflorus) and chia (Salvia columbariae).
Near your feet, along the roadsides are many common, introduced or
“weedy” native species scattered along the route. These plants, often
referred to as a ruderal community, are mostly annual species that arrived
with the first Europeans to California and have spread into such disturbed
soils as road edges. They include grasses like slender wild oat (Avena
barbata), red brome (Bromus madritensis subsp. rubens), ripgut grass
(Bromus diandrus), fescue (Vulpia myuros), smilo grass (Piptatherum
miliaceum), and others like filaree (Erodium cicutarium), cliff dandelion
(Malacothrix saxatilis), gray mustard (Hirschfeldia incana) and tree
tobacco (Nicotiana glauca). A few of these same plants have been
identified from seeds in adobe bricks in the first missions in Southern
California, so we know they arrived as early as the 1770s. One invasive
plant of concern is the Arabian pea (Bituminaria bituminosa) which has
spread along the Clamshell Road edges and crowds out native vegetation.
Rare Plant Species
The hillsides contain some plants of limited distribution in southern
California, including one federally Endangered species, and several
sensitive species.
Braunton’s milk-vetch
Photo:: Mickey Long
Monrovia’s signature rare plant, Braunton’s milk-vetch (Astragalus
brauntonii), a federally-designated endangered species, is a stout perennial
shrub in the pea family (Fabaceae) and occurs in brushy places, along
fire breaks and road cuts in the chaparral and coastal sage scrub. Its
distribution is in low hills bordering the plain of Los Angeles from the
Santa Monica Mountains to the San Gabriel and Santa Ana Mountains
between 50 and 1650 feet elevation. Within its range the species is
historically rare and is restricted to few localities, a number of which have
been destroyed and the species extirpated. The shrub produces pale lilaccolored flowers between March and July, followed by wooly pea pods, and
Braunton’s milk-vetch
Photo: Cliff McLean
is relatively common during early successional stages after fire and then
slowly declines, remaining as a seedbank until the next fire or disturbance.
There are several historical and current populations of Braunton’s milkvetch in the foothills of Monrovia. One population currently known from
along the Clamshell roadbed and road cuts consists, during good rain
years, of up to 1600 plants, some mature and many seedlings.
San Gabriel Mountains leather oak
Photo: Mickey Long
Watch along the road for a low, shrubby oak, the San Gabriel Mountains
leather oak (Quercus durata var. gabrielensis). This scrub oak variety,
a small evergreen shrub three to nine feet tall, is a California Native
Plant Society (CNPS) sensitive taxon and is known only from the San
Gabriel Mountains between about 1370 and 3000 feet and is considered
threatened by urbanization. Here on the hillsides, numerous individuals of
this scrub oak occur on slopes with mixed chaparral and oak woodlands in
both Lower Clamshell and Ruby Canyon drainages.
Another oak, found here at its northernmost geographic distribution,
becoming increasingly rare in our area but found as individuals along the
road, is Engelmann oak (Quercus engelmannii). This tree, a deciduous
oak, fifteen to fifty feet tall, occurs from Los Angeles and Riverside
Counties south through San Diego County and northern Baja California,
Mexico. This sensitive species (CNPS), is threatened by development and
repeated fires.
Plummer’s mariposa lily
Photo: Rick Fisher
In late spring through summer, beautiful lavender and maroon flowers
of Plummer’s mariposa lily (Calochortus plummerae) may be seen
on narrow one and one-half to two-foot stalks that come up each year
from an underground bulb. An uncommon plant species, significantly
reduced by development, this lily is known only from foothills and lower
mountain slopes, from Ventura and Los Angeles Counties through Orange,
Riverside and San Bernardino Counties.
Wildlife in the Preserve
by Kim Bosell
The Hillside Wilderness Preserve is an ecotone (a transition area where
two communities meet and integrate) called the urban fringe. With the
vast Angeles National Forest to the back and the resource-rich urban
development to the front, this area is a hot spot for wildlife homesteading
and travel. Wildlife survival is based on the ability to find and access food,
water and shelter. The urban fringe offers alternate water resources in a
dry year, yummy tasting fruit trees and ornamental plants found in urban
landscaping, as well as pet food and tempting human garbage. The forest
offers an easily accessible habitat for dispersing offspring, natural food
sources and provides cover for covert movement from east to west across
the city. These factors increase the abundance of wildlife that will occur
here, just as it would in a completely natural ecotone. Increased resources
(natural or unnatural) mean a higher diversity of species that will utilize
an area. This high diversity of wildlife species is an important reason to
educate yourself on how to respect and protect all the creatures that make
use of the Hillside Wilderness Preserve.
Red-tailed hawk
Photo: Lou Orr
Wildlife that exist in the urban fringe can be categorized any number of
ways. The most valuable information is knowing what wildlife is active
within the habitat at any given time and what wildlife you are most likely
to come across while visiting the area. Wildlife activity is broken up into
daytime use (diurnal animals), nighttime use (nocturnal animals) and those
most active at dawn and dusk but may also be active into the day or night
(crepuscular animals).
When visiting the Hillside Wilderness Preserve during the day, you are
likely to see a few of the seventy-seven resident and migratory bird
species recorded during field studies. Species such as the red-tailed
hawk, turkey vulture, western scrub-jay, Anna’s hummingbird, mourning
dove, black phoebe, northern mockingbird, wrentit and house finch are
commonly observed. Other frequently seen diurnal animals within the
Hillside Wilderness Preserve include the western fence lizard, alligator
lizard, side-blotched lizard, western newt, darkling beetle, pale swallowtail
butterfly, California sister butterfly, common hairstreak butterfly, western
gray squirrel and California ground squirrel. Some wildlife, although
active, choose to live in a less obvious fashion by keeping out of sight and
moving only when not threatened. These would include the western skink,
horned lizard, striped racer, California kingsnake, western whiptail lizard
and tarantula. Rarely seen diurnal wildlife include patch-nosed snake,
ringneck snake and California mountain kingsnake.
Buck and doe
Photo: Kim Bosell
As dusk approaches the landscape, commonly seen wildlife such as
the mule deer, Audubon’s cottontail rabbit, California mouse and brush
mouse become active and head out to feed. Crepuscular animals may also
be active in bright moonlight or during the day when food is abundant.
Although rarely seen, the mountain lion, bobcat, black bear and coyote
typically use this active time for hunting and foraging. They can, however,
be active in both daytime and nighttime if spooked from a resting spot, if
a meal becomes available, are enticed by mating season or if it becomes
necessary for safe movement.
Photo: Chuck Haznedl
Gray fox
Photo: Kim Bosell
Photo: Chuck Haznedl
Nocturnal wildlife has adapted night vision, hearing and advanced
sense of smell in order to find food and survive in the dark. You may
have an opportunity to see an owl or bat cross the night sky but most
nocturnal wildlife is seldom seen. Nocturnal wildlife found in the Hillside
Wilderness Preserve are great horned owl, barn owl, big brown bat,
western pipistrelle, Pacific kangaroo rat, big-eared woodrat, gray fox,
raccoon, Virginia opossum, striped skunk, Pacific treefrog, California
treefrog, and legless lizard. The ringtail cat, a beautiful raccoon relative, is
rarely seen and is usually active only in the early morning hours in order
to reduce competition for food and to evade predators.
Several species of wildlife can be potentially dangerous. Rattlesnakes
carry a powerful weapon called venom. There are biting and stinging
insects such as black flies and yellow jackets. There are also large
carnivores such as the mountain lion and black bear that roam the area.
Of course, the most hazardous species wandering the Hillside Wilderness
Preserve is the human species. It is important to always be alert when
hiking. Wildlife will defend themselves if startled or if they feel
threatened. If you respect their space, never approach and keep a healthy
distance, you may have an incredible wildlife encounter as you observe
animal behavior in the natural habitat.
If you are attempting to locate wildlife on your hike, here are some tips:
• Stay on the trail and hike as quietly as possible
• Be alert to small noises which may indicate movement
• Watch well ahead for sign of movement, tracks, nests or holes
• Take your time
• Move slowly and sit in one place for awhile
The Country Rat
Pacific rattlesnake
Photo: Terry Keller
Ever wondered why there are seemingly random piles of sticks, leafy
branches, cactus, and a variety of other materials piled four feet high and
four feet wide in the preserve? These piles are woodrat homes, often used
by several generations. The random piling is designed to trick and confuse
predators with multiple layers to dig through, several entrances and exits,
bits of sage used to conceal the woodrat odor and cactus spines lining the
openings. The woodrat is also known for its hording mentality, picking up
and bringing back any interesting object it may come across, causing it to
commonly be referred to as the pack rat.
Western pipistrelle bat
Photo: Chuck Haznedl
Up to sixteen species of bats are flying over the hills at night through
spring and summer. Although these nocturnal creatures go almost
completely unnoticed they can easily be seen feeding as the sun sets. Not
only are they the only type of mammal that fly, these amazing mammals
provide a great benefit to humans. The only type of mammal that They
are capable of catching and eating over 600 mosquitoes in an hour,
reducing disease risks such as west nile virus, encephalitis, dengue fever
and malaria. They also play an important role in the pollination and seed
dispersal for many plants.
What can you learn from that scat?
One thing we know for sure, is that all wildlife must eliminate waste
leaving behind evidence of their passage in the form of fecal piles, called
scat. With a closer look one may see plant or fruit seeds, remnants of
insects or grasses, or animal hair and/or bone. Scat can tell us what type
of animal it was by its shape and size or how long ago it came through by
its moisture content. Scientific scat analysis tells us that 80% of a coyote’s
diet is vegetation and over 95% of a black bear’s diet is vegetation and
insects. So they are carnivores by opportunity only.
The smartest cat
Photo: Terry Terrell
Actually the smartest cat is not a cat at all but commonly called a miner’s
cat based on its historic affinity to the early miner’s cabins. Its true name is
a ringtail, considered clever for its adaptable and sneaky nature. Ringtails
reduce competition and are seldom seen by humans by choosing to feed in
the early morning hours. They take advantage of their excellent climbing
ability to move through shrubs and trees raiding bird nests. About the
size of a gray squirrel, with large eyes adapted for night vision it moves
through open areas with its long banded tail up over its back confusing
nighttime hunters such as the great horned owl.
Bear necessities
Black bear
Photo: Keith Johnson
The black bear is one of the largest predators in the preserve area with the
males weighing in at an average of 400 pounds and females 250 pounds.
Its preferred meal consists of avocados, loquats, berries, grasses, ants,
termites and bee larvae. The black bear is an opportunistic feeder and will
most often choose sitting and feeding at a fruit tree or shrub loaded with
berries versus chasing down another animal. Although not an aggressive
animal, they should be respected and always given their space. Never
approach; let the bear know you are there by talking and back away
slowly, signaling that you are no threat. Do not turn your back or run.
Staying fit
You may come across a sleek little lizard working out in the hot sun on a
rock as you approach. Why is he doing push-ups? Well he either thinks
you’re a threat or someone to impress. This display is used to defend
territory from competing males or to attract females. The push-ups are
performed to show the beautiful blue colors located on the chin and belly.
This western fence lizard gets it common name from its preference for
elevated perching area such as a fence.
Western fence lizard
Photo: Lou Orr
Bird Brain
It has time and again been noted that corvids are very smart birds. Crows
and ravens have been shown to mimic sounds including human voices and
utilize their surrounding to assist feeding such as dropping hard shelled
food on rocks or dropping seeds in the street to be run over. But a true
representation of their intelligence is the act of anting. When encountering
ants, a crow will often flatten itself on the ground with its wings extended.
Then standing again it will pick and tuck the ants into its plumage. In
defense the ants secrete a formic acid that repels bird lice in the feathers.
The ants may also feed on feather mites another parasite that can destroy
feathers. An amazing example of mutually beneficial connections.
Changing of the guard
Gray squirrel
Photo: Keith Johnson
The gray squirrel is the local native tree squirrel species that historically
would have been found throughout the Monrovia area. The introduction of
the eastern fox squirrel in 1907 and the spread of the species, coinciding
with years of drought and susceptibility to mange have put the two species
in competition for food and space. With both species being arboreal and
comparable in size, food habits, and nesting preferences we have seen the
changing of the guard in the urban areas of the city. But where the habitat
remains with dense cover, bountiful oaks and limited development the
gray squirrel populations still hold on.
Insects and Their Relatives
by Steven R Kutcher, MA
The Monrovia Hillside Wilderness Preserve has plants and environmental
conditions similar to those of other coastal foothill locations. Part of this
area was once a plant nursery. And non-native plants have been introduced
in the area. Insects of the Monrovia Foothill Wilderness Preserve are easy
to find if you know where to look.
Arthropods (jointed leg) are a group of invertebrate animals that are
characterized by an exoskeleton made of chitin and have a segmented
body to which jointed appendages are articulated in pairs. Arthropods
include insects (e.g., butterfly, ant, and beetles having six legs); arachnids
(e.g., spider, tick, and mites having two body parts and eight legs);
crustaceans, e.g., sowbug (“wood lice”), pill bug, and amphipod (two body
parts and ten to fourteen legs); and millipedes and centipedes both having
two body parts and more than thirty legs.
Variable checkerspot
Photo: Paul Levine
Scarlet skimmer dragonfly
Photo: Paul Levine
Male vivid dancer
Photo: Emile Fiesler
Arthropod species and numbers are influenced by their habitats, seasons,
weather conditions, plant species, time of day, and migration patterns.
The preserve contains introduced plants that influence various insect
populations. Facultative insects (insects that feed on a variety of food
sources) will use introduced plants as a food source. Microhabitats are
places where insects can be found. Most insects may remain unnoticed
because of their small size and their ability to be hidden from view. Hikers
seem to be aware of annoying insects (see Nuisancearthropods below).
An excellent reference to the identification of arthropods is the book
Insects of the Los Angeles Basin by Dr. Charles Hogue, 1993. The
majority of observed arthropods will be large. Examples of larger insects
are butterflies, dragonflies, and ground dwelling beetles. The first insects
observed are usually associated with flowers or plants, flying insects, or
species walking on the ground. Many native perennial plants are adapted
to be green all year long. Host specific insects include the yucca moth
which are found only on yucca and the monarch butterfly. The caterpillar
will only be found on or near their host plant milkweed (Asclepias sp.).
Grasshoppers are general feeders and will be found on a variety of plants.
Some common or distinctive arthropods likely to be found during year in
the Monrovia preserve will include the following:
First arthropods to appear in late winter and early spring: Insects can be
found throughout the year. Some of the first insects to appear with new
plant growth are crane flies (Tipulidae) sometimes known as mosquito
hawks (they cannot bite), march flies (Bibionidae), orange-tip butterfly
(with orange tips on their white wings). Some insects like the cabbage white
butterfly (an introduced species) may be found during most of the year.
Continued on page 14
The official map of the preserve
from the City of Monrovia
The creators of this brochure
are not responsible for any
Flowers and arthropods
Carpenter bee
Photo: Paul Levine
Many insects visit flowers for a source of nectar, pollen, a protective
place, or to locate a mate. The type of flower influences which insects
will be attracted to it. Some common nectar feeders are the European
honey bee (Apis mellifera [not a native insect]), carpenter bees (are about
one inch long, the females are colored black while males are goldenyellow colored), bumble bees (they are colored black with yellow bands),
and burrowing bees (make round holes in the ground). There are many
members of the pea family including introduced Spanish broom and the
Arabian pea that support and encourage bee populations. A variety of
wasps also visit flowers. Flies that visit flowers include: bee flies, hover
flies (Syrphidae), tachinid flies (Tachinidae which are generally parasitic
on insects). Butterflies (see Common butterflies), moths like noctuid and
geometrid moths will fly at night and occasionally day flying moths like
the tobacco hornworm may be seen. Many small arthropods, especially
beetle and spider species, can be found on flower umbels like ceanothus
or blue elderberry. Thrips are found on many types of flowers and can be
seen by tapping the flower on a sheet of white paper.
Arthropods on plants
Sonoran bumble bee
Photo: Emile Fiesler
Spittle bug
Photo: Paul Levine
Arthropods have a close association with plants. They are found on all
parts of plants including roots. Larger common plant dwelling arthropods
are: True bugs (Heteroptera), harlequin bug, box elder bug also found on
the ground, plant bugs, stink bugs (Pentatomidae), ambush bugs, and their
relatives aphids and fulgorid bugs. Cicadas are much easier to hear than
see (the sound is sometimes mistaken for that of a rattlesnake). Lace bugs
are found on shrubs and sycamore trees. Spittlebugs are found on shrubs
(e.g., California sagebrush, Artemisia sp.). Beetles include: lady bugs (lady
beetles or ladybird beetles) are often red but some are also colored black
and gray. Longhorn beetles (Cerambycidae), leaf beetles (Chrysomelidae)
and a number of other small beetle species will be found on plants
especially if there are small flowers in a cluster or umbel. These can be
seen by tapping the flower cluster on a sheet of white paper. Caterpillars
include: genista broom moth caterpillars on genista broom, inchworms
(Geometridae), Checkerspot caterpillars on sticky-monkey flower
(Scrophulariaceae) and a variety of other plants. Careful observation may
reveal lacewings, grasshoppers, katydids, tree crickets and the praying
mantis all of which are camouflaged on plants.
Small insects
Many arthropods are overlooked because they are generally a quarterinch or less. These arthropods include: aphids, wasp parasites, white flies,
thrips, scale insects, gall wasps, psyllids, springtails, mites, lacewings,
deer flies, (horse flies are rare), small beetles (many families), and gnats.
Nocturnal insects
Moths, especially Noctuidae (millers), Geometridae (inchworms),
Arctiidae (tiger moths), and many other small species of moths. Many
species of beetles are active at night including: june bugs, ground beetles,
weevils, longhorn beetles (Cerambycidae), and soldier beetles. Other
nocturnal insects include crickets, tree cricket, cockroaches, ichneumon
wasps, and have nocturnal activity behavior patterns. Many species are
attracted to lights when the moon is half-full or less.
Common butterflies
Longhorn beetle
Photo: Paul Levine
Butterflies will be found on or near flowers. They generally fly in the sun
and along trails and open spaces. Some species rise with air currents to
the top of a hill. This behavior is called “hill topping.” Some common
butterflies are: Cabbage white (not native), the common white, the marbled
white, dusky wing skipper, other species of skippers, pale swallowtail,
tiger swallowtail, cloudless sulfur, and the chalcedon checkerspot. The
California sister and Lorquin’s admiral are associated with oaks and will
perch on branches. Other butterflies include: the ringlet, Euphydra (marine
blue), pigmy blue, west coast lady, painted lady, buckeye, mourning cloak
and occasionally the dainty white.
Ground dwelling arthropods
Lorquin’s admiral
Photo: Paul Levine
Velvet ant
Photo: Emile Fiesler
Carpenter ant
Photo: Emile Fiesler
Parasites and predators found on the ground include: spider hunting wasps
(sphecid wasps), cuckoo wasp, tarantula hawk, and velvet ants. The male
velvet ant is a wasp that has wings and is pale brown in color. The females
have no wings and have white or red and black fuzzy hair covering
their body. Velvet ants crawl on the ground in search of burrowing bees
to parasitize. Ants are important on the preserve and they include: the
harvester ant, field ant (Formica francoeuri), velvety tree ant (Liometopum
occidentale) and carpenter ants.
Conspicuous insects found on the ground include darkling beetles,
wooly darkling beetle, iron clad beetle, and other types of tenebrionid
beetles, ground beetle (Carabidae), the band-wing grasshopper, ant lion,
and the bee fly. Crustaceans like the pill bug, sow bug, and amphipod
require higher humidity and are close to contact with moist soil. Spiders,
mites and small beetles may be found in decaying organic matter and in
association with fungi. The Jerusalem cricket (Stenopelmatus fuscus) is
native to Southern California and may be found in moist areas under rocks
and fallen logs, as can earwigs, silverfish, bristletail, sowbug, pillbug,
amphipod, native cockroach species, centipede, and millipedes.
Flies and Gnats
Midges, and small flies may fly around your face and eyes. Common flies
are the flesh flies, blue bottle flies, muscid flies, robber flies, no-see-ums,
canyon flies, deer flies, syrphid flies (hover flies), tachinid flies, and phorid
flies. Gnats will cluster in flying groups at dusk.
Bees and Wasps
Tarantula hawk wasp
Photo: Paul Levine
Yellow jacket, Polistes wasp, cuckoo wasp (with metallic green colors),
sphecid wasps (mud dauber, sand wasp), spider wasps (tarantula hawk,
[Pompillidae]), small parasitic species of wasps (many families), sweat
bees (Halictidae), leaf cutting bees (Megachilidae), true bees (European
honey bee, bumble bee (Apidae), and the carpenter bee (Anthophoridae)
are associated with flowers.
Aquatic associations
A cluster of yellow jackets
Photo: Lou Orr
Black and yellow argiope spider
Photo: Emile Fiesler
Any water pooling in canyon areas will attract aquatic insects including:
dragonflies, damselflies, dobsonfly, mayfly, stoneflies, as well as a number
of aquatic beetles. Butterflies, bees, and wasps will drink water at mud
Some common spiders include: Jumping spiders, identified by two large
eyes (Salticidae); funnel weavers or grass spider makes funnel web
(Agelenidae); wolf spider, which have two large eyes and are found on
the ground (Lycosidae); orb web spiders (Araneidae), tehriidiid spider,
and cobweb spiders (Theridiidae). Cobweb weavers make their webs
in places like dead stumps or places that are not disturbed. Crab spiders
(Thomisidae) are often found in flowers or flower heads and can change
colors to match the color of the flower. There are also many small ground
dwelling arthropod species found among fallen leaves and ground cover.
Occasionally the green lynx spider (Oxyopidae) is spotted on a green
plant. Spiders can digest their own silk. At the end of the season spider
webs appear to be more numerous on vegetation. In the fall native male
tarantulas may be observed searching for a mate. They are brown or
brownish black, not aggressive, and need not be feared. Scorpions are
present but rarely seen and are nocturnal.
Nuisance arthropods
Photo: Steven R. Kutcher
Ticks attach to bushes and will be easily dislodged and attach themselves
onto a mammals passing by. Always do a “tick check” after hiking. Check
all areas of your clothes especially below your waist when you look for
ticks. If you find a tick on your clothes you can brush it off. Have someone
look for ticks in the areas you cannot easily see and look again when you
get home. Other Arthropods that may be a nuisance include the canyon
fly, buffalo gnat, mosquitoes, deer flies, mites, and yellow jackets. Some
of these insects will investigate a person’s odors, food, bright colors,
perfume, sweat, and moisture.
Enjoy the Monrovia preserve! There are some wonderful native species
of arthropods to enjoy in Monrovia. Arthropods are good indicators of
biodiversity in the preserve. Greater species diversity means a healthy habitat
and provides pollinators and a food source for many other creatures. There is
much you can learn by taking the time to watch an insect.
Human Interaction
by Christopher Nyerges
It’s the year 850. It will still be a long time before
the Spanish move into upper California and begin
establishing missions, which was one of the factors
leading to the demise of the traditional native way of
life in this area.
Standing up in the hills north of what will one day be
called Monrovia, there are no freeways in the valley
below. No supermarkets, no hardware stores, no
hospitals, no fast food restaurants. Just a vast expanse
of oak and grass woodlands. Along the streams way
to the south, you might notice rising smoke along
some the riverside village sites. You were born here,
you were trained here, you live here. Everything you
need can be obtained from the land, and just about
everything you need is found in this section of land
called the Monrovia Hillside Preserve.
Though there is no evidence that there were Indian
village sites or encampments in the area called the
Monrovia Hillside Wilderness Preserve, this site
provided many of the most basic plants that were used
in the everyday life of the Native Americans who
once exclusively resided here. Let’s take a look at the
richness of this land from a traditional native’s point
of view.
Acorns matured from the various oak trees every
autumn, and families would collect as much as they
could for the winter. It would not be uncommon to
collect a ton of acorns to be used until they were
available again in a year. Due to the use of fire, acorns
in the old days were said to last longer in storage—
fire hardened the shells and killed off some of the
bugs that eat the acorns.
To use for food, the acorns would be shelled, and then
ground on rocks into a meal. Water would be poured
over the meal until all the tannic acid was removed.
The most common method of consumption in the old
days would be to add to stews as a thickener or gravy.
Black walnuts were collected in the fall, and
their meat was eaten. It takes a rock to break open
the native black walnuts. Sometimes, the green fruit
was picked early, crushed, and tossed into ponds and
streams to stun the fish. Also, the half shell of the
acorn would be kept and used in a game like dice.
Cattails were a valuable plant for food, shelter,
weaving, and even medicine. In the springtime, the
yellow pollen at the top of each green flower spike
was shaken out into a container and collected. The
yellow pollen is sweet and was added to various
dishes. It is also very fine, and could be used as
a talcum for babies. The young green spike was
eaten, as were the young shoots that arise from the
rhizhome. The long slender leaves of the cattail were
useful in making some baskets and other woven
items. It doesn’t have high tensile strength, but is
useful for a number of craft items. Even the halfdomed homes, typically made of willow or mulefat
frames, were covered thatch-like, in bundles of the
cattail leaves. Even the flower stalk was sometimes
used for arrow shafts.
Toyon tree fruits in winter with its orange-red little
fruits. These were collected and would be dried and
ground into a flour to be added to other dishes. They
were also just dried and eaten. Sometimes they’d be
boiled, and the water became a sweet beverage with a
hint of sour. Good straight shoots of toyon were used
for arrow shafts.
Manzanita fruit was used in several ways. The
ripe fruit can be eaten as a nibble, and the seed spit
out. More often, the fruits would be ground into stone
grinders, the seed removed, and the flour-like fruit
portion would be used to make beverages, or added
to acorn flour (and other dishes) to add flavor, and an
aspic-like quality.
Wild grapes were generally sour, and were
improved by drying or cooking. They were used
by the local natives. The leaves also were probably
cooked and eaten.
Buckwheat is a widespread characteristic plant
of the chaparral, with its rosemary-like leaves and the
balls of white flower clusters that turn brown in the
fall. The brown flower clusters were collected, ground
somewhat after removing stems, and used to make hot
porridge, in which acorns and other meats and greens
would be added. This would have been a desirable
food, since it required no leaching like the acorn, and
it was easy to collect.
Chia is an annual member of the mint family that
springs up with the winter rains, and goes to seed
by early summer. The seeds were collected and then
made into drinks, or ground into flour and added
to other foods. The native chia, also called golden
chia, is the high-protein seed that Indian runners and
traders of the desert region used for their protein.
Yucca, though thought of primarily as a fiber
source, provided several good food sources. When
the plant is in its final year, it sends up a large
flower stalk. The immature stalk, as it arises, has the
appearance of a large asparagus. This stalk was eaten
when young, usually dried, sometimes made into
flour, and eaten later. Though it could be eaten raw, it
is best if cooked. The flowers that appear on the stalk
were eaten in olden times, as they still are in parts of
Mexico and Guatemala. Though there are many ways
to eat them, they were typically made into a soup, or
flour was added and they were cooked into paddies.
The yucca fruits—following the flowers—were
picked while they were still white inside, and then
baked in the coals of a fire. These were particularly
prized, and had the flavor of squash. If the fruits were
allowed to mature, flat black seeds develop, which
were used in olden time as one of the many seeds to
be ground into flour.
Cherry trees ripen in July and August, and were
enjoyed in the old days just as people today enjoy
cherries. However, the flesh of wild cherries is thin—
especially in dry years—and with a hint of bitterness.
But the main food from the cherry would have been
the inside of the seed, what today is called the “pit.”
This was shelled, and cooked, and then used with
other seeds and flour to make a variety of dishes.
Native Americans in
the San Gabriel Valley
Painting: Joseph Holbrook
Courtesy City of Duarte
Bracken fern is an easily recognized edible fern
that is found in the shadier sections of the preserve.
In the old days, as today, the newly emerging tender
tips of spring are snapped off and eaten, usually when
cooked first.
weeks, the fibre is more readily extracted.Then the
fine fibre is twined, and it is from these twines that
netting has been made.
Elder berries have long been used for food. They
can be dried for future use, and then (fresh or dried)
can be made into beverages, and a variety of desserttype items.
Sometimes various plant poisons were used to stun
fish, such as crushed green walnuts, soaproot, or
yucca. There are many other plants that had been used
in the old days to stun fish, but at least we know that
these three could be found on the Monrovia Hillside
Preserve property.
Bows made from willow, or ash or elder. Typically,
a very straight shoot would be selected and dried.
Once dried, it would be slowly carved down with a
sharpened rock to produce what is called a self-bow.
Sandstone-type rocks would be used to sand it down
to the final shape and final smoothness.
Arrow shafts made from mulefat or willow and other
suitable woods. These were made by cutting many of
the shafts, bundling them, and letting them dry. When
dry, they’d be final-straightened, nocked, fletched, and
the tip would be sharpened. Many times a fore-shaft
of some harder wood would be secured to the tip.
In the old days, nets were typically used to take fish,
and the netting would be made from yucca and other
suitable fibers. Once the yucca leaves have been
either gently pounded or allowed to rot in water a few
Medicine was as complex in the old traditions as
is modern medicine, and perhaps even more so. It
involved the knowledge of herbal uses of plants, the
insight of the psychologist, the spiritual attunement
of the priest, and modern doctor’s knowledge of the
human body and physiology. Many herbs were used,
alone or in combination with others, for healing.
Other methods included fasting, sweating, water, and
rest. Some of the common medicinal plants found in
the preserve included the following: willow, mugwort,
sage, cherry.
Soap plants that have been used in the old days are
found on the property. A soap plant is any plant that
contains a high enough volume of saponins so that
when rubbed with water and agitated, a soapy froth
develops which is used for cleansing. Here are the
soap plants that are found on the preserve.
Amole soaproot is a bulbous plant with long
linear and wavy leaves. The bulb is dug up and the
layer of outer fibers removed. The bulb—or a section
of it—would be crushed, mixed with water, and then
agitated between the hands to create a thick soap. It
was an excellent soap for most uses.
Yucca’s fresh leaves were another good soap plant.
The green leaves would be shredded, wet, and then
agitated in a container with water, or between the
hands, to produce a frothy green soap.
Ceanothus, or the wild lilac, is a beautiful
chaparral bush (or tree) when it flowers in the spring.
Then, this rather ordinary inconspicuous bush can be
sighted for some distance with its white or lavender
flowers. In the old days, the buds, flowers, and fruits
of the mountain lilac could all be used for soap.
They could be simply mixed with water and rubbed
between the hands to produce a very mildly fragrant
soap. And the soap wouldn’t be available only in the
spring. The fruits can be dried for years, and then
ground up to a powder, mixed with water, and still
made into a fine soap.
Wild cucumber is a sprawling vine that covers
whatever native vegetation that happens to be nearby.
The plant produces these green, oval-shaped fruits,
approximately the size of a small tennis ball, covered
with spines. As the fruits mature, and dry up, a lufflike structure remains. This was once used just as the
modern luffa is used, for cleaning the skin as well as
other items in need of a cleaning.
While the native people who lived in the valley below
could have found all the materials they needed for
fire-making near their village sites and along the
rivers and streams, all these plants are also found
within the Monrovia Hillside Wilderness Preserve.
For the hand drill, a straight piece of mulefat was
used. It would be about as thick as a modern pencil
and maybe eighteen inches long. The hearth—the flat
piece of wood onto which the drill would be pressed
and spun—was typically cut from a piece of willow.
Shredded elder bark and the dried leaves of mugwort
provided sufficient tinder to get the ember produced
from the hand drill into a flame. Sometimes, large
tinder bundles were made in order to transport a coal
from camp to camp. This was made from a large
cigar-shaped bundle of mugwort or elder bark, which
could smolder for hours.
Many everyday items were made by weaving and
twining fibers of plants that were long, flexible, and
of even thickness. Some of the objects made this way
would include baskets, carrying bags, nets, sandals,
articles of clothing, etc.
When we’re speaking of baskets, the stiffer stems
would become the spokes (warp) of the basket—such
as basketbush plant, poison oak, thin willows (often
split), mulefat, and buckwheat stems. More flexible
leaves would be the weavers, such as cattail, or yucca,
and any of the others as well, when properly prepared.
Within the range of the preserve, there are many
plants that would have been used in the old days for
weaving such objects.
Most paints and pigments that are collected in nature
tend not to last long when painted on rocks, or
surfaces exposed to the elements. Even paintings on
bows or bark generally do not last long. In the old
days, the seeds of wild cucumber were crushed and
mixed with the various plant or mineral pigments to
make paints that would survive the elements.
NOTE: The reader should never eat any plants until
they have been positively identified. The information
given here is insufficient for identification, and the
reader must pursue classes or books on ethnobotany,
such as Gregory Tilford’s Edible and Medicinal
Plants of the West (1997) or my Guide to Wild Foods
and Useful Plants (1999). Also, it may not always be
legal to pick plants, so always get permission first.
by Alice Griselle
The history of the Monrovia Hillside Wilderness Preserve spans over three decades
and involves thousands of advocates that played an important role in its formation.
A detailed account could fill a book and read like a novel. The following is a brief
history to give the reader a sense of the effort and time that created this lovely place
for all to enjoy.
In the 1980s, precipitating events that ultimately influenced the creation of the
Hillside Preserve were the development of Gold Hills with fifty-four lots and the
submittal of a preliminary subdivision plan for additional lots on the San Lorenzo
Nursery Property in Cloverleaf Canyon. Additionally, a 130-acre Lux Arboretum
property in the Cloverleaf Canyon area was donated to the city which was significant
acreage to start a preserve area.
The pressure to develop the hillsides became of concern to the City of Monrovia and
the city council appointed a group of hillside property owners and residents to the
hillside advisory committee. For the next ten years, the committee worked diligently
with the consulting firm of Planning Associates to develop a comprehensive plan
to sensitively provide for development in the hillsides. Specific plans were created
for the Cloverleaf Canyon, Norumbega, and Madison Avenue areas with specific lot
locations and sizes, restrictive contour grading conditions, and sightline restrictions.
The planning commission hearings to consider the specific plan were contentious and
lasted for many months.
As a result of the difficult and numerous planning commission meetings that went
far into the night, two conservancies had been formed to advocate for limited
development or outright purchase of the hillsides. Starting in January 2000, the
city council held a series of public hearings. On March 16, 2000, the city council
approved Land Plan “C Modified.” Land Plan “C Modified” covered the properties
contained in the original cloverleaf canyon specific plan and those added by
subsequent amendment to the specific plan area, the Madison Avenue and Norumbega
specific plans.
The city council unanimously voted to place several related hillside measures on
a special election ballot which were referred to as Measures A and B. Measure
A ratified the city council’s decision to maintain the lowest possible density by
establishing development densities and zoning definitions for properties that could
be purchased and held as undeveloped open space. Measure B authorized a special
tax to generate $10 million over thirty years (through the annual revenue stream or
as a bonded lump sum) to purchase land zoned as “Hillside Wilderness Preserve”
and “Hillside Recreation Area” as permanent open space, and $80,000 per year of on
going property tax revenue for future maintenance of the areas.
The Measures A & B Committee worked to educate the voters on the importance
of the preservation of the hillsides. The voters overwhelmingly passed Measures A
(84%) and B (77%) at the July 11, 2000, election. The election did three things: (1)
Approved a new “Wilderness Preserve” and “Hillside Recreation” general plan and
zoning classifications; (2) Approved a parcel tax to acquire hillside open space; and,
(3) Ratified the city council’s March 16, 2000, approvals of Plan “C Modified” for the
hillside areas.
In August, the city council appointed a wilderness preserve steering committee
to develop an open space acquisition plan to direct and prioritize acquisition of
properties. The process for the purchase of the properties provided considerable
opportunities for public input with forty-eight committee meetings. From 2002 to
2009, eleven transactions for purchase of properties were completed with city bond
and state grant monies. The total expenditures were $25,000,000 of which $9,000,000
came from the city and the balance was funded by the state. These properties were
added to the hillside properties that were already owned by the city such as the
Arboretum property and formed the 1,416-acre project area. Purchase of the hillside
properties by the city prevented over one hundred homes and associated streets and
utilities from being constructed.
The Monrovia Community Services Commission was designated as the advisory
body to oversee the stewardship of the project area, protect important natural
resources, and where appropriate, recommend passive recreation opportunities.
The state grants require that the city preserve and protect all natural resources in
perpetuity and provide for walking, hiking and bird watching opportunities. A trail
committee was appointed by the community services commission to advise them on
historic trails and potential trails. A resource management plan was commissioned
and followed a framework of core values and goals established by the community and
approved by the community services commission in 2005. The community services
commission conducted meetings from August 2006 to September 2008 to discuss
public access alternatives and resource management strategies. On January 20, 2009,
the city council adopted the resource management plan. Subsequently, the use of
a mitigated negative declaration for approving the resource management plan was
legally challenged and the city then completed an environmental impact report which
was ratified by the city council.
With the resource management plan in place and funding from Measure B, the
community services department and community services commission continue to
guide the implementation of a trail network.
All cited materials are available at the Eaton Canyon Nature Center
1750 N. Altadena Dr., Pasadena, CA 91107 • (626) 398-5420
Sharp, R. & Glazner, A. (1993). Geology Underfoot in Southern California. Missoula, Montana;
Mountain Press Publishing Company.
Bornstein, C. & Fross, D. & O’Brien, B. (2005). California Native Plants for the Garden. Los Olivos,
California; Cachuma Press.
Dole J. & Rose, B. (1996). Shrubs & Trees of the Southern California Chaparral & Mountains, An
Amateur Botanist’s Identification Manual. North Hills, California; Footloose Press.
McLean, G & McLean, C. (2008). Plants of the San Gabriel Mountains: Foothills and Canyons,
Interpretive Guide on CD for PC and Mac. Los Angeles, California; Nature at Hand.
McLean, G & McLean, C. (2003). Common Plants of Eaton Canyon and San Gabriel Foothills, Field
Guide on CD. Los Angeles, California; Nature at Hand.
Insects and Arthropods
Heath, F. (2004). An Introduction to Southern California Butterflies. Missoula, Montana; Mountain
Press Publishing Company.
Hogue, C. (1993). Insects of the Los Angeles Basin. Los Angeles, California; Natural History Museum
of Los Angeles County.
Clarke, H. (1989). An Introduction to Southern California Birds. Missoula, Montana; Mountain Press
Publishing Company.
Garrett, K & Dunn, J. & Small, B. (2012). Birds of Southern California. Olympia, Washington; R.W.
Morse Company.
Reptiles and Amphibians
Stebbins, R. & McGinnis S. (2012). Field Guide to Amphibians and Reptiles of California, Revised
Edition. London England; University of California Press.
Jameson, Jr., E.W. & Peters, H. (2004). Mammals of California, Revised Edition. London, England;
University of California Press.
History, Native Americans and Environmental Awareness
Campbell, P. (2007). Earth Pigments and Paint of the California Indians, Meaning and Technology.
Los Angeles, California; Paul Douglas Campbell, Publisher.
Lightfoot, K. & Parrish, O. (2009). California Indians and Their Environment, An Introduction.
London, England; University of California Press.
Lowry, J. (2006). The Tracker’s Field Guide. Guilford, Connecticut; The Globe Pequot Press.
Nyerges, C. (2006). How to Survive Anywhere: A Guide for Urban, Suburban, Rural, and Wilderness
Environments. Mechanicsburg, Pennsylvania; Stackpole Books.
Created by the
Monrovia Hillside Wilderness Preserve
Interpretive Committee
Kim Bosell
Bruce Carter
Alice Griselle
Steven R Kutcher
Mickey Long
Christopher Nyerges
Glen Owens
Steve Pokrajac
Gary Wallace
Designed by Jeff Lapides of First Water Design
Photo: Mickey Long
Your Interpretive Guide to the
Monrovia Hillside
wilderness Preserve
Monrovia, California