Pinnacles National Park

Pinnacles National Park

Natural World

The rolling chaparral and dramatic rock faces of Pinnacles National Monument inspire loyalty in visitors, from picnickers to rock-climbers, and from stargazers to cave explorers. Pinnacles is visually stunning, as anyone who has seen the smooth orb of the moon glide from behind the crags of the High Peaks can attest, or who has watched the flashing black and white wings of acorn woodpeckers as they tuck acorns into the thick bark of gray pines. This striking beauty is attributable, in part, to the Monument's geologic formations, showcase chaparral habitat, finely intergraded ecosystems, and protected native plant and animal diversity. Another special Pinnacles quality is its proximity to millions of people. We invite you to come and visit this corner of the National Park Service: Pinnacles National Monument.

Established in 1908 to preserve the incongruent and beautiful rock formations for which Pinnacles is named, the Monument originally protected only 2,060 acres. It now encompasses about 26,000 acres in the southern portion of the Gabilan Mountains, one of a series of parallel northwest-trending ridges and valleys that make up the Central Coast Range.

Pinnacles National Monument, located near the San Andreas Fault along the boundary of the Pacific Plate and the North American Plate, is an excellent example of tectonic plate movement. The Pinnacles Rocks are believed to be part of the Neenach Volcano that occurred 23 million years ago near present-day Lancaster, California, some 195 miles (314 km) southeast. The giant San Andreas Fault split the volcano and the Pacific Plate crept north, carrying the Pinnacles. The work of water and wind on these erodible volcanic rocks has formed the unusual rock structures seen today.

Fault action and earthquakes also account for the talus caves that are another Pinnacles attraction. Deep, narrow gorges or shear fractures were transformed into caves when huge boulders toppled from above, and wedged in the fractures before reaching the ground. These boulders became the ceilings of the talus caves that now entice not only people, but also several kinds of bats.

The topography of Pinnacles is not all spire and crag, however. Elevations range from 824 feet along South Chalone Creek to 3,304 feet atop North Chalone Peak, and much of the Monument consists of rolling hills.

Pinnacles has a Mediterranean climate of hot, dry summers and cool winters with moderate rainfall. Although the Monument is only 40 miles from the Pacific Ocean, the Santa Lucia Mountains to the west strongly modify the ocean influence before it reaches inland to Pinnacles. Consequently, while on the coast summer temperatures might be a fairly steady 60 degrees Fahrenheit, at Pinnacles the temperature can swing from 50 degrees at night to 100 degrees in the day. Similarly, due to the absence of the ocean's warming effect, winter temperatures at Pinnacles often drop below freezing while coastal temperatures remain moderate. Average rainfall is 16 inches per year, falling mostly from January through March. Snow occurs in small amounts at higher elevations almost every year between mid-December and January.

Weather profoundly influences vegetation, and broadleaf chaparral is one of the vegetation types adapted to the Monument's summer heat and drought, as well as to the daily temperature extremes. Composing about 80% of the Monument's vegetation, the chaparral ecosystem is not one thing, but many, with subtly varied vegetation composition quilted together over the land. Along with chaparral, there are woodland, riparian, grassland, and rock and scree habitats here, all also subtly intergraded. It is the variability of Pinnacles' topography, weather and microclimate, and the location of the Monument at the edge of intersecting ecosystem zones, that allows for the diverse vegetation and intricate mix of habitats found here. These diverse habitats in turn support a rich fauna - especially of birds, reptiles and bees. According to Western scientific knowledge, Pinnacles' 400 bee species represent the highest bee diversity per unit area of any place on earth.

Pinnacles is a refuge for species representative of the central California coast not only because of the many ecological niches here, but also because of its long-term protected status. The bottom line of the soils and vegetation has been protected, maintaining a relatively high proportion of native plants. In fact, chaparral vegetation at Pinnacles is a showcase example of this ecosystem that elsewhere up and down coastal California has largely been extirpated or is losing ground before urban expansion. In turn, many populations of native animals have the habitat they need, and have survived here. In the case of large predators with big ranges, however, adjacent land management practices have altered the wildlife habitat, eradicating populations such as bears and wolves, and making it difficult to sustain others, such as mountain lions and coyotes. Nevertheless, Pinnacles has relatively abundant populations of wildlife, which contributed to Pinnacles National Monument becoming one of three current release sites in the United States for the California condor, which last flew over the Monument in the 1980's.

Visitors are drawn to Pinnacles for other reasons, too. In the spring, wildflowers subtle and bold decorate the land, and the bird population swells with migrants. Solitude, dark night skies, and deep quiet are found here, especially in the more than 16,048 acres of federally designated wilderness within the Monument - one of the two federal wilderness areas nearest to the San Francisco Bay Area. Rock-climbers and hikers, both solitary and social, are regulars here. Whether you want to count butterflies, condors or stars, Pinnacles National Monument is likely to reward you with new pleasures each time you visit.

Natural Features & Ecosystems

Pinnacles National Monument gets its name from rock spires and crags that are remnants of an ancient volcano. The volcano eroded over millions of years as it moved northward along the San Andreas Fault. Rock debris in the form of boulders has weathered and settled, leaving behind spires of volcanic rock and talus caves.

Air Quality

Typically, Pinnacles National Monument has superb “Class I” air quality. Occasionally north winds and a persistent inversion layer draw air pollutants from the Santa Clara Valley into the Monument. The NPS Air Quality Office and EPA established a monitoring station near the east entrance in 1987. An air clarity study (using a transmissometer) has been completed, but particulate and ozone monitoring continues. Despite the occasional hazy days, the air quality at Pinnacles is a defining feature of the Monument and an important resource.

While Pinnacles enjoys good air quality, the trend has been towards a declining air resource. The encroaching urban landscape will reduce the distance between pollution sources and the Monument.
The Clean Air Act provides the primary authority for protecting and enhancing the nation's air quality. In 1977, Congress amended the Act to prevent the significant deterioration of air quality in clean air areas of the United States and to protect visibility in certain areas, including Pinnacles. The Clean Air Act established three classifications of varying degrees of restriction of allowable air quality deterioration. Pinnacles National Monument was designated a Class I area. This is a mandatory designation, requiring the federal land manager to protect the air quality-related values of the Monument from air pollution impacts. Air quality-related values include visibility, plants, animals, water quality, historic and cultural resources, and other resources which could be impacted by air pollution.

Park managers work closely with the state and the Environmental Protection Agency to prevent future and eliminate existing visibility impairment at Pinnacles by participating in regulatory decisions (e.g., air quality permits, plans, and rules). They also work cooperatively with State and private interests to resolve air quality-related resource conflicts and ensure that identified vistas (and any future vistas similarly identified) are adequately protected.

The Monument began visibility monitoring in 1986 with the installation of an automatic camera at the Chalone Peak Lookout. The camera location was changed a year later to monitor visibility conditions looking towards the High Peaks. In 1987, particulate and ozone monitoring equipment was installed at an indoor station near the east entrance to the Monument. Meteorological parameters monitored include wind speed and direction, temperature, dew point, solar radiation, and precipitation. In 1988, remote visibility began to be monitored with the installation of a transmissometer. The transmissometer was removed in 1993, at study.

A more proactive role in protecting the air resource needs to be taken. Partnerships with local private and public interests need to be established. While interpretation of air quality has recently been addressed with wayside trail exhibits, this effort falls short of what is necessary to alert the public of the impending problem of poor air quality, and educate them on alternatives.

Water Quality

Good water quality is important for the plants and animals of the riparian community. Fish, aquatic insects, amphibians, and perhaps endangered species could easily be affected by poor water quality. High bacteria counts have been observed in the Monument. In 1972, E. coli counts as high as 16,000 ppm contributed to a die off of several mammal species. The US Public Health Service identified the culprit as infection due to the bacterium genus Arizona (closely related to genus Salmonella).

Riparian areas are the most heavily used by visitors and are where most structures are located. Human impact such as littering and human waste can adversely affect long reaches of stream. Routine limnological surveys of the Monument’s surface waters are one potential monitoring solution. Aquatic insects and amphibians may also be utilized as indicator species of overall surface water quality.

Domestic Water Supply
Good water quality is also important for visitor and resident safety. The east side headquarters and residence area is serviced by a well that taps the valley alluvium near the east entrance. That source is reliable and recently replaced a well near the old Chalone Creek campground. The west side offices and residences are serviced by a deep artesian well that requires no pumping. Those sources are treated regularly to guard against public health threats. An analysis of an east side well in 1959 yielded chemical data on a domestic water well. That data showed that the water had a pH of 6.7, moderate hardness, specific conductance was 407, and contained 280 ppm of dissolved solids.

Climate and Weather

The climate of Pinnacles is typical of the Mediterranean climate of California, with cool wet winters and hot dry summers. Summer temperatures of over 100 degrees are common, but coastal fog will often come into the valleys at night. Nighttime summer temperatures of 50 degrees are common, making for enormous daily temperature swings.

Winter climate is akin to the California deserts, with mild days and nights often dropping into the low 20s. The average precipitation is approximately 16 inches per year. Nearly all of the precipitation is in the form of rainfall, with the majority occurring from December to March. Snowfall is rare, but does occur in significant amounts about every 10 years.

The great variability in seasonal precipitation is due to the east Pacific high. This dominant weather feature shifts northward in the summer to shunt storms far to the north. Occasionally this feature brings subtropical moisture into central California from southerly latitudes, producing one to five thundershowers per year in the Monument. Mostly, however, the east Pacific high acts as a giant valve completely shutting off precipitation for long stretches of the year.

California is known for its long dry and wet cycles. Changes in the East Pacific high shift on approximately a six-year cycle. The result is persistent drought for five to eight years, followed by a wet period. Such cyclic variation is an important consideration in vegetation, wildlife, and water management.

Hydrologic Activity

Hydrologic activity at Pinnacles National Monument can be divided into two categories: surface water and ground water. Surface water is usually very sparse in the hot, dry summers, but ground water is always present as little as a few feet below the surface of the creeks.

Development within the park has had an impact on water resources, and work is being done to restore creek dynamics and habitat in riparian areas. A road that separated the creek from its floodplain is being removed so that the creek can access its natural boundaries. In the future, park managers need to collect more information about Chalone Creek, especially the impacts that development has had on its dynamics.

Surface Water
Chalone Creek is the major drainage of the Monument. Most of the 25 square miles drains into this tributary which eventually empties into the Salinas River and Monterey Bay. The terrain in the Gabilan Range is rugged and deeply dissected. There is no regular drainage pattern as streams are controlled by fault traces and fractures at intersecting angles.

The tributaries of Bear Gulch Creek and Chalone Creek originate just outside the Monument boundary. Most of Sandy Creek, which joins Chalone Creek near the east entrance, originates outside the Monument. Chalone Creek and Sandy Creek are unimpeded throughout their course in the Monument, but their uppermost branches on private lands are impounded (submerged under a lake or pond because of a stream barrier) in small stock ponds.

Bear Gulch Creek is impounded behind a dam within the Monument built during the CCC-era. That reservoir is not being used for domestic purposes, although it may now be depended upon by wildlife. Flowing water is generally found from November through early May. Water exists in the reservoir year-round and in small sheltered plunge pools along stream beds.

Runoff is primarily due to rain generated by Pacific cold fronts typical of a Mediterranean climate. Fog, dew, and convective storms may contribute to plant moisture but do not generate stream runoff. The runoff regime is similar to arid zones in that stream response is flashy, ephemeral, and sometimes a source for groundwater recharge.

Nine springs are known and marked within the Monument, although small seeps may appear seasonally in wetter years. Springs generally occur along fault lines, such as Willow Springs, along rock fractures, or along lithologic contacts. Springs are no longer used as domestic water supplies for facilities due to their inadequate water production.

Ground Water
The diversity of geology strongly affects ground water. Three geohydrologic units are present: 1) granitic and metamorphic rocks, 2) volcanic rocks-- the Pinnacles Formation, 3) and porous sedimentary rocks-- the Temblor Formation. Most of the Monument is underlain with volcanics. Surrounding the central area of volcanics are granites of the western and southeastern sides, and sedimentary rocks of the northeast side.

Three northward trending faults that traverse the Monument have produced structural traps for groundwater. The valley alluvium, particularly along the east entrance road and South Chalone Creek, is a reliable source of groundwater. One well produces over 10 gallons per minute. The Temblor Formation is less well studied, but another potential water source.

When surface streams have gone dry in the summer months, groundwater continues to flow through the valley alluvium. This alluvium, with a depth of at least 38 feet (12 m), is permeable and of high hydrologic conductivity. Where the valley crosses a resistant rock unit, this groundwater is often brought to the surface in perennial pools.

Flood Potential and Fluvial Geomorphology
Studies by the USGS have identified the 100-year floodplain along lower Chalone Creek and surrounds. Since little storm-specific rainfall data and related streamflow data exist, estimates were generated with a computer program. This produced a reasonable demarcation of areas of potential inundation, as is required by Executive Order 11988 (Floodplains and Wetlands). The USGS report also contains several surveyed stream crossings which can be useful in future fluvial geomorphology studies.

Floodplain data is important in limiting damage to Monument structures and allowing appropriate space for natural floodplain processes and function. Despite the seasonal and ephemeral nature of surface water within the Monument, it is no less important than elsewhere. The basic threat is an overwhelming lack of data. Water quality should be periodically monitored. Changes in channel morphology and riparian structure should also be monitored, preferably after significant runoff events approximately every 5 to 10 years. Baseline data needs to be collected, monitoring stations should be established, and there should be full compliance with Executive Order 11988 (Floodplains and Wetlands).

Of specific concern is allowing the stream to access the floodplain. The presence of appropriate riparian vegetation is important in maintaining a natural sediment flux, and habitat for riparian species. In-stream and near-stream structures have not been analyzed for their impact upon future flood dynamics or their impact upon channel morphology. Land use patterns outside the Monument have the potential to adversely affect channel morphology within Monument boundaries.

Baseline data such as soil infiltration rates, unit stream discharge, estimates of stream flow with corresponding rainfall totals, and simple channel surveys have not been collected to this point. The 100-year flood plain assessment was constructed with little real data. The study clearly points out its own shortcomings where computer models were built on regional averages instead of data collected in the Monument.

It also acknowledges the mobile nature of the streambed. If this streambed were to be altered during a flood, the corresponding high water mark would change. This analysis needs to be rerun with actual data. Therefore, a program to collect actual stream and channel data needs to be initiated as soon as possible. Additionally, the computer model of high water lines needs to be corroborated with geomorphic features along the channel.

The residence area at Chalone Creek Housing Area is serviced by a leach field buried in the porous alluvium near the stream. Although no problems have been attributed to its proximity to surface and groundwater, it may warrant closer monitoring. This should be included in a monitoring program.

After comprehensive baseline data on water quality is collected, a few targeted tests should be selected and conducted frequently. Finally, managers should be satisfied that groundwater withdrawals within and outside the Monument do not affect the quantity or quality of water available for plants and wildlife along riparian corridors.

Environmental Factors

Geologic forces have created the landscape of Pinnacles, but a climate of hot dry summers and winter rains has also shaped the terrain. The vegetation of the park transforms each year as the rain stops and temperatures climb; hillsides go from vibrant green to golden brown within days. Many of the chaparral plants thrive when fires burn through to make room for new growth. Streams that are dry throughout the summer can flood during the winter and spring rains.

Non-native species and development have also had an impact on the monument. Exotic species of both plants and animals have threatened the native vegetation and wildlife. Roads and trails have created erosion and affected sensitive riparian areas. Park managers are working to limit the damage caused by these factors.

Vegetation at Pinnacles National Monument may be broadly grouped into five major habitat types or vegetation associations, described below. These associations result from a web of interactions amongst the various plant species and such factors as soil type, direction of exposure, slope, moisture regime and fire history. Recognizing the plants that characterize an association allows us to see the patterns of these co-occurring factors.

The most widespread plant community, chaparral occurs just about everywhere you look. Found on shallow or deep soils, north- or south-facing slopes, moist canyon bottoms or exposed upper ridges, eighty-two percent of the monument is covered by some type of chaparral. All chaparral associations share similar characteristics, though the species composition and structure differ in relation to environmental factors.
This vegetation type is composed mostly of shrubs up to two meters tall, and is adapted to grow in warm climates with little or no summer moisture, and variously wet winters. To survive and even thrive in the long hot summers, many of the plants have evolved adaptive traits such as small waxy-coated leaves, deep taproots, shrubby stature, water storage structures, and summer dormancy.

In addition, many chaparral plant species have adapted to the natural occurrence of fire. For example, seeds of some chaparral plants lie dormant in the seedbank for years before a fire stimulates them to sprout. Dependent on disturbance and seedcoat scarification for seed germination, the plants may appear suddenly after a fire, even in areas in which they have long been absent.

Chamise, with small needle-like leaves, is the dominant shrub at Pinnacles. Spikes of white flowers bloom at the tips of the branches from May through July. Chamise grows in mixes of other species, including buck brush, manzanita, holly-leaved cherry, mountain-mahogany and black sage. The composition of the chaparral varies depending on soil type and direction of exposure, amongst other factors. The many species of the annual and perennial understory also vary depending on moisture and exposure. As a general rule, dry south-facing stands have fewer species than moister north-facing stands.

Woodlands, the second most common association in the monument, occur from lower riparian areas to upper exposed slopes of North Chalone Peak, and are characterized by trees with annual grasses and forbs in the understory. The main woodland association at Pinnacles is the blue oak woodland, comprising 10 percent of the total vegetation cover in the monument. Gray pine, California buckeye, valley oak and live oak appear both in this and the riparian associations. In the woodland habitat type, however, these tree species are only minor components, while in riparian areas they play a more significant role. The woodland understory is a mixture of non-native grasses, perennial native grasses and a variety of annual and perennial forbs.

This habitat type is restricted to the valley bottoms and sheltered, moist canyons of the monument. The species are deep-rooted and require more water than any of the other vegetation associations. Large deciduous and evergreen species dominate, such as sycamore, cottonwood, and California buckeye, often growing directly in small creeks and streams. Other major species include valley oak, live oak, and gray pine, as well as willow and mule fat. The understory in this community consists of shade-loving perennials with few annual species.

Found in most of the same areas as the rock and scree association described below, and closely related, grasslands have shallow soils that prevent the establishment of deep-rooted species. Dominant species include introduced grasses such as brome; native and non-native annuals including fiddleneck and filaree; and a variety of mostly native herbaceous perennials like lomatiums.

Rock and Scree

Though the rock and scree habitat type is the least common in the monument, its dramatic spires and rock faces inspired the establishment of Pinnacles National Monument. Named for its predominant substrate, the association is characterized by having little or no soil. This slight but important difference in soil depth largely accounts for contrasts between the vegetation of this and the grasslands habitat. Despite demanding conditions, some plants have developed the ability to flourish here. Bitter root and two-leaved onion, for example, are among the most spectacular plants in the monument, and are found in rocky areas of the High Peaks, Balconies and South Chalone Peak.

Vegetation Mapping

A vegetation map is a pictorial representation of the plant communities covering a given area of land. Groups of plant species that commonly occur together are delineated in a patch-like configuration on a map. These maps, with layers of detail such as species composition or soil type, become useful tools in understanding interactions between the biological and the physical world. Vegetation maps illuminate biological trends, such as an exotic weed taking over a native ecosystem, or the regrowth of vegetation after fire. Vegetation maps can also indicate the type of habitat where given rare plants or animals might be found, such as Pinnacles buckwheat (Eriogonum nortonii) or the San Joaquin coachwhip snake (Masticophis flagellum ruddocki). In addition to correlating the species with the habitat type, the map can reveal relationships that underlie the correlation, answering the question of why the given species is found in the habitat, or what specific characteristic of the habitat is associated with the species. For instance, in mapping valley oaks (Quercus lobata), the location of the oaks is consistently associated with fine soils on a geomorphic landform known as a Pleistocene Terrace. Information of this kind is vital for responsible management of the resources in our parks. Now, due to a national emphasis on Inventory and Monitoring within the National Park Service, Pinnacles National Monument is carrying out a two-year Vegetation Mapping Project.

Vegetation Map

The Pinnacles National Monument Vegetation Mapping Project will utilize IKONOS digital satellite imagery as a foundation for the map. Information about the vegetation, collected through extensive field sampling in 2003 and 2004, will be analyzed statistically by the University of Montana's Wildlife Spatial Analysis Lab in order to diagram the relationship between the images and the vegetation - ultimately producing a map segmented into identifiably differentiated vegetation types.

The vegetation sampling program at Pinnacles employs a method of data collection called a relevé. Relevé standards were developed by the California Native Plant Society in 1995, and require that field crews thoroughly inventory the plant species in a given area and determine the amount of cover taken up by each species. The crews also record GPS data, soil texture, topography, local site history, and photographic information for each location. Working in teams of two in 2003, the mapping crew at Pinnacles surveyed approximately 250 plots, many of which were located in chaparral, California buckwheat, and woodland vegetation communities. By June of 2004, the Pinnacles crew will have completed the roughly 650 plot surveys necessary for generating an accurate vegetation map.

Vegetation Classification

Before the map can be correctly segmented into vegetation alliances, it is necessary to classify the vegetation, meaning to be able to define repeatedly distinguishable vegetation types. This botanical classification will follow standards for sampling and analysis set forth by the National Biological Survey and the California Native Plant Society. By following standards for data collection and analysis, we will essentially "speak the same language" as other researchers, so that we can easily share information and make straightforward comparisons with vegetation classifications in other geographical areas. The final classification system will encompass a variety of vegetation types, from those abundant at Pinnacles, to those that occupy little of the Monument's 24,500 acres - as long as the vegetation types can be reliably differentiated. Some examples of vegetation types or alliances that will be visible on Pinnacles' vegetation map are listed below:

Adenostoma fasciculatum Adenostoma fasciculatum - Arctostaphylos glauca Adenostoma fasciculatum - Ceanothus cuneatus var. cuneatus Adenostoma fasciculatum - Salvia mellifera Aesculus californica Arctostaphylos glauca Artemisia californica California Annual Grassland Ceanothus cuneatus var. cuneatus Cercocarpus betuloides var, betuloides Eriogonum fasciculatum var. foliolosum Juniperus californica Pinus sabiniana Prunus ilicifolia ssp. ilicifolia Prunus ilicifolia ssp. ilicifolia - Fraxinus dipetala Quercus agrifolia var. agrifolia Quercus douglasii Quercus lobata Rhamnus ilicifolia Salix laevigata Salix laevigata - Populus fremontii Salvia mellifera Selaginella bigelovii

Exotic Plants

At Pinnacles National Monument, out of approximately 625 plant species, about 100 are nonnative. Several of these species are invasive, with the potential for creating serious ecological damage and detracting from the uniqueness of the monument’s native plant community. Pinnacles National Monument Weed Control Program is focused primarily on horehound (Marrubium vulgare), mustard (Hirschfeldia incana), and yellow star thistle (Centaurea solstitialis). Weed control efforts focus on these three species because of their potential for native habitat destruction. Yellow star thistle and mustard are controlled by working through a sequence of large areas on a monthly basis. Horehound is much closer to being eradicated within the monument and is controlled by monthly visits to 140 small plots. Eradication methods include hand pulling and herbicide application.                     

Yellow star thistle (Centaurea solstitialis)  
Yellow star thistle is considered one of the most invasive weeds in California by the California Exotic Pest Plant Council. It has already degraded over 25 percent of the land in California and is called “the plant that ate California”. Yellow star thistle is a summer-blooming annual in the Sunflower family and native to Eurasia. The plant is found primarily in open, disturbed areas such as road edges and stream channels, but through time moves increasingly into undisturbed locations, including meadows and riparian corridors.

Yellow star thistle produces a deep taproot, which extends below the zone of root competition of associated annual species. This allows yellow star thistle to grow well into the summer after most other annuals have dried up. Each seed head produces stiff spines, 1-3 cm long that make the plant unpalatable to wildlife and painful for park visitors. Yellow star thistle is less abundant and somewhat less widely distributed within the monument than mustard. Nonetheless, it imposes a serious long-term threat because of its ability to produce large numbers of seeds and its growth during the hot summer months.

In January 1999, an integrated pest management (IPM) action plan was drafted for managing yellow star thistle at Pinnacles. The control objective of the IPM action plan was to reduce the abundance of yellow star thistle to 5 percent of its abundance at that time by the year 2002.

Horehound (Marrubium vulgare)
Horehound is an herbaceous perennial plant native to Europe that arrived in North America as a cultivated herb. It reproduces readily by both seed and vegetative means. The seed is readily distributed by wildlife and visitors due to recurved barbs on the seed which attach to fur and clothing. It is likely that animal fur, possibly the fetlocks of horses and the fur of small animals, has transported horehound seeds at Pinnacles because horehound infestations are often located at corral sites and animal burrows. The monument staff has been successfully controlling horehound since the late 1980s.

Summer Mustard (Hirschfeldia incana)
Summer mustard is a biennial native to the Mediterranean. The plant was first established in southern coastal California and now can be found in Oregon, Idaho, Nevada, and Washington. Summer mustard grows extremely well in disturbed, open and sunny areas. In the first year of growth, the mustard plant produces a rosette; in the second year, the plant bolts, flowers, sets seed and dies. The plant blooms May through October and in late fall forms dense stands of brittle woody seed stalks. At Pinnacles, summer mustard is out-competing native plant species, encroaching on trails and the dried seed stalks are creating hazardous fuel buildup.

In December of 1998, Pinnacles received an anonymous donation to be applied to the removal of mustards. In 1999 an IPM action plan was developed and removal began in early 2000.


The peak blooming season at Pinnacles is from March through May, when over 80 percent of the monument’s plants are in bloom. Depending on rainfall and temperature, flowers can begin opening as early as January and continue into June or, in a really wet year, into July. Manzanita, milkmaids, shooting stars, and Indian warriors are the most common early bloomers in January and February. By March, bush poppies and buck brush are the dominant flowering shrubs, along with forbs such as California poppies, fiddleneck, peppergrass, filaree, fiesta flower, monkeyflower, and baby blue-eyes.

In April, most of the March-blooming species are still blossoming, and such species as Johnny-jump-ups, virgin's bower, gilia, suncups, chia, black sage, pitcher sage, larkspur, and bush lupine have joined the spectacular display. A few early blooming species may still be seen in May, but center stage will be occupied by species that enjoy hotter, drier weather, such as chamise, buckwheat, clarkias, orchids, penstemons, and roses. Though late-blooming species may still be seen in early June of wet or cool years, by mid-June or early July, summer sets in and few blossoms are to be found.


Pinnacles National Monument has an abundant and diverse lichen flora that is strikingly visible to the visitor and functionally important to the park’s ecosystem. The rock outcrops for which Pinnacles is named are a key habitat for a great diversity of the park’s lichen flora. Many of the rock surfaces appear to be painted in shades of red, orange, yellow, green, and brown due to the prolific lichen growth. These lichens undoubtedly contribute to rock weathering through chemical processes, although it is likely minor compared to other physical processes (i.e. freeze-thaw). The unique soil lichen communities found on open talus slopes in the chaparral vegetation community are crucial in stabilizing soil. The crowns and trunks of oak trees in the oak woodland communities are typically plastered with lichen, covering nearly every available surface. This dense lichen growth provides food, shelter, and camouflage for a variety of arthropod species. The long, pendulous lichens dangling from oak branches are commonly used as nesting material for birds and rodents, and occasionally as fodder for deer. In addition, lichens aid in nutrient cycling and the control of stand humidity. Finally, lichens are used as indicators of air quality, stand age, and stand continuity.

In 2003, we inventoried the lichens at Pinnacles National Monument. The primary objective of the project was to create a comprehensive lichen species list and reference collection for PINN. The secondary objectives were to 1) collect preliminary distribution and relative abundance information, 2) obtain GPS data for new occurrences of rare lichens found through inventory efforts, and 3) identify lichen species that are suitable for use in long-term monitoring programs. The results of this inventory plus all previous records bring the total number of lichens known to occur at Pinnacles National Monument to 293. It is estimated that another 40-50 species remain to be found here.

Pinnacles National Monument Lichen Checklist

Although Pinnacles National Monument is not home to such charismatic megafauna as bison, bears, or blue whales, it supports healthy populations of many kinds of smaller animals such as bobcats, bats, and bees. There are 149 species of birds, 49 mammals, 22 reptiles, 6 amphibians, 68 butterflies, 36 dragonflies and damselflies, nearly 400 bees, and many thousands of other invertebrates.

While we often associate certain animals with particular habitats, many animals require more than one type of habitat to meet all of their needs. For example, bats that roost in caves may forage for insects above water, dragonflies that spend most of their lives near water may hunt above chaparral, and animals living throughout the Monument will leave their usual habitat to visit watering holes. Subsequently, some of the best wildlife habitat is near the edge where one type of habitat meets another. Much of Pinnacles is covered by a mosaic of different habitats, resulting in a great diversity and abundance of habitat edges. Miles of hiking trails traverse these edges, offering great wildlife viewing opportunities.

Pinnacles is also a place of edges on a broader geographic scale. It is at the interface of northern and southern, coastal and inland, wet and dry. For example, the Bernardino dotted-blue butterfly and the phainopepla reach the northernmost extent of their ranges near here, and the chestnut-backed chickadee is not found much farther south. Demonstrating the interplay of wet and dry, a Gabilan slender salamander and a desert night lizard may live together in the same decaying log.

Aside from being a place of edges, Pinnacles is also an island. It is an island of fairly intact natural habitat in a sea of growing human development. Pinnacles and the surrounding area is the only home of the big-eared kangaroo rat, Gabilan slender salamander, Pinnacles shield-back katydid, and Pinnacles riffle beetle. But it is also a refuge for many common species typical of California. We may currently take these species for granted, but as natural habitats throughout California continue to diminish, these species will become much less common and widespread. The Monument was once home to the California grizzly bear, black bear, and foothill yellow-legged frog, and, in 2003, after a hiatus, again became home to the California condor. Though humans have extirpated some of the large animals, and we have lost certain vulnerable species, healthy populations of many animals appear to be strong within Pinnacles’ protected boundaries.

In order to protect wildlife at Pinnacles, animals may not be fed, captured, or harassed in any way. Binoculars are a great tool for observing all sorts of wildlife from butterflies to frogs to falcons, because they provide a close-up view from a distance that does not disturb the animals. If you have an interesting wildlife sighting, please take careful notes on where, when, and what you saw and report it to a Monument employee.


Birds are the most visible animals visitors are likely to encounter at Pinnacles National Monument, with over 140 species documented in the park since 1908. Turkey vultures circle and soar in the skies overhead, while acorn woodpeckers and Steller’s jays call noisily among the pines and oaks near the visitor centers. In the winter, dark-eyed juncos and California towhees perch and forage around willows and underbrush. In the spring and summer, black-headed grosbeaks and warbling vireos sing loudly from oaks and pines as they set up nesting territories.

The variety of habitat types at Pinnacles attracts a diverse assemblage of birds to the park for seasonal nesting and migratory stopovers, and numerous species live in the park year-round. Much of the bird diversity at Pinnacles is focused along the riparian corridors of Bear Gulch and Chalone Creek, because they provide an abundance of food, water, and shelter for many species. In spring and summer, house wrens, black phoebes, yellow warblers, yellow-breasted chats, lazuli buntings, and varied thrushes are active in shaded riparian areas. Cooper’s and sharp-shinned hawks maneuver agilely through the trees in search of prey, and mallards and belted kingfishers are seen occasionally along the creeks and at the reservoir every year.

Certain species favor the pine and oak woodlands in the park. Among the gray pines, western tanagers, Townsend’s warblers, and hairy woodpeckers are evident. In the oak woodlands, California quail, oak titmice, western scrub jays, mourning doves, ash-throated flycatchers, and northern flickers are commonly seen.

The dense, low scrub of the chaparral covers the majority of the park, and provides ideal habitat for many birds, including residents like California thrashers, spotted towhees, wrentits, and bushtits, and seasonal species including sage sparrows.

The rocky summits and peaks of Pinnacles provide nesting habitat and roosts for many raptors, including prairie falcons and golden eagles, as well as smaller bird species including the vocal canyon wren and the acrobatic violet-green swallow. At night, the haunting calls of great-horned owls can be heard echoing off the cliff walls.

Resource management staff at Pinnacles study bird populations through raptor monitoring, small bird point counts, and California condor reintroduction efforts. For detailed information on the projects, refer to the Highlights section on the left side of this page.


At first glance, Pinnacles National Monument may not seem like a place for amphibians. Nevertheless, six species of these moist-skinned creatures live here in this land of hot, dry summers and only sixteen inches of rain per year. Pacific tree frog (Pseudacris regilla), California red-legged frog (Rana aurora draytonii), and western toad (Bufo boreas) breed in streams and ponds. The two frogs spend most of their time near water, while the toad leaves the water after breeding. Arboreal salamander (Aneides lugubris), ensatina (Ensatina eschscholtzii), and the recently described Gabilan slender salamander (Batrachoseps gavilanensis) are terrestrial, spending their entire lives away from water. They lay their eggs in moist places such as decaying logs. They are fairly common, but are rarely seen due to their secretive nature.

The best time to see most amphibian species at Pinnacles is on warm, rainy nights (especially November and March). They may also be active during the day in the rainy season. Western toads are active in the evening through May. California red-legged frogs are uncommon and found mostly near ponds and deep sections of streams in spring and summer. Pacific tree frogs are abundant near streams and ponds, and may be heard calling during all but the driest months of the year. They are both the smallest and the loudest species. Their tadpoles are widespread and commonly seen throughout spring and early summer. Red-legged frog and western toad tadpoles are usually found in only a few places in the Monument. Red-legged frogs are listed as a Threatened species under the Endangered Species Act. They were once common at Pinnacles, but their population now seems to be in trouble. An effort to re-establish a population at the Bear Gulch Reservoir is currently in its third year.

Several other amphibians are worth mention. Foothill yellow-legged frogs were historically abundant in Pinnacles streams, but have not been seen here in several decades. A re-introduction plan for this species is being considered. Western spadefoot toads were historically in the Monument in low numbers, but there have been no current sightings. This species and the California tiger salamander have apparently healthy populations nearby and may inhabit the periphery of the Monument. The California newt, although common across the Salinas Valley to the west, is conspicuously absent from this area.

If you are lucky enough to find an amphibian at Pinnacles, give it some space and take time to watch it. Their moist skin is very sensitive, much like that of your eyes, so the salts, oils, sunscreens or soaps on your hands can cause them harm. Please do not turn over rocks or logs to watch them, or attempt to catch them. We have few reported observations of what they eat, where they burrow, or other behaviors. If you observe any such behavior, or a species not normally seen here, please take careful notes and share them with a Monument employee.

Dragonflies and Damselflies

Although at first glance Pinnacles National Monument may appear to be a vast arid landscape, a little exploration will reveal occasional welcome water sources. Streams, springs, ponds, and the Bear Gulch Reservoir support an abundance of life. In 2001, park biologists began a two-year project to inventory the aquatic macroinvertebrates of Pinnacles. The goal of the project was to collect and identify every species of worm, snail, crustacean, arachnid, and insect that lives in or around water and can be seen with the naked eye.

One conspicuous group of aquatic macroinvertebrates is the dragonflies and damselflies, collectively called odonates. These familiar insects can be seen darting about almost anywhere there is fresh water. So far, twenty-four species of dragonflies and sixteen species of damselflies have been identified from Pinnacles, with more almost certainly to be found.

Adult odonates are voracious predators, catching flying insects with their mouths or with their spiny legs held out like a basket. One look at their huge eyes will tell you that they have great eyesight for spotting their prey. Unlike other insects, their front and hind wings beat in opposite directions, giving them excellent maneuverability in flight. They are also among the fastest flying insects.

Many odonates live for just a few weeks as adults. They have only this short time to reproduce, so when they are not resting or feeding they are often involved in reproductive activities. A male spends much of the day either perching and keeping a watchful eye over his territory or patrolling back and forth through it. Females lay hundreds or thousands of eggs by poking them into the bottom of shallow streams or into plant stems, dipping them onto the water surface, or dropping them from the air into the water or onto moist soil. After mating, a male will often guard a female or remain attached to her as she lays her eggs, in order to ensure that she does not mate again.

Young odonates (naiads) live in water and are wingless, barely resembling their parents. They are also voracious predators, eating small invertebrates and even fish and tadpoles. Some live among aquatic plants, others burrow in sand or mud, and others sprawl in dead leaves on the stream or pond bottom. This latter type is often hairy so that mud and bits of sticks and leaves cling to them for camouflage.

You can sometimes see odonate naiads by looking in shallow water. On plants and rocks near water you are likely to see shed exoskeletons left behind from naiads that transformed into adults. If you happen to see an adult emerging from an exoskeleton, please do not disturb it. It will be very fragile until its wings and body have dried and hardened. If you wait patiently, you may get to watch its first flight!

Watching adult odonates can provide hours of entertainment. Their aerial acrobatics are astounding. With a little study and practice you can often decipher the reasons behind their behavior: chasing prey, laying eggs, drinking water, guarding a mate, patrolling a territory, regulating body temperature... Their bright colors make many species easy to identify, but keep in mind that males and females of the same species may look quite different. If two dragonflies are interacting, they are likely to be the same species. This is not as likely for damselflies.

California Red-legged Frogs

For the first time in nearly 20 years hikers visiting the Bear Gulch Reservoir have the opportunity to see California Red-Legged Frogs (Rana aurora draytonii). This species was once common there but disappeared in the early 1980s, probably because of an infestation of exotic Black Bullhead Catfish (Ictalurus melas).

The catfish were put there by someone who wanted to fish at the reservoir. In 1985, park staff drained the reservoir and removed all the catfish (approximately 1,700 pounds). Although healthy populations of frogs existed in streams within a few miles of the reservoir, they did not return on their own. This is not surprising, considering the obstacles such as roads, buildings, caves, and waterfalls along the way.

The frogs living along the streams seemed to be doing well in the early 1990s, but by 1998 their numbers were extremely low. Because they lay their eggs in streams in early spring, late-season floods may wash away eggs as well as any frogs that don't get out of the way of the rising water. Large floods in 1995 and 1998 may have been responsible for the decline. Another contributing factor may have been an infestation of exotic Green Sunfish (Lepomis cyanellus), which are known to prey on tadpoles. In 1998-1999 we used electro-shocking to remove all Green Sunfish (more than 3,500) from streams within the monument. Yearly monitoring has revealed no re-infestation.

The Bear Gulch Reservoir provides frogs with a breeding site that is much less prone to the threats of floods and exotic fish. Given enough time, a healthy population of frogs along the streams would eventually be able to re-populate the reservoir. However, because they are declining here and elsewhere, we decided to give them a head start. In collaboration with Norman Scott of the USGS, we developed a re-establishment plan.

With the approval of the United States Fish and Wildlife Service, we began a pilot project in Spring 2001. We transported nearly 1000 eggs from nearby streams to the reservoir. We moved half of each of two egg masses, just before they hatched. Because young tadpoles are especially vulnerable to predation, we kept them in protective pens for their first few weeks. Once they had reached sufficient size, we released them into the reservoir. We monitored their survival, and by August they began to transform into frogs. Surveys in the fall found 17 young California Red-Legged Frogs at the reservoir.

In spring 2002 we moved half of three egg masses from streams to pens in the reservoir. These 1,200+ eggs hatched within a few days and by mid-June there were over 900 surviving California Red-Legged Frog tadpoles in the pens. We released these tadpoles into the reservoir and by October there were 160 newly transformed California Red-Legged Frogs, as well as 15 one-year-old frogs from last year’s efforts, in the reservoir and nearby Bear Gulch Cave.

In spring 2003 we moved just over 900 eggs (half of a single egg mass) from the stream to a pen in the reservoir. In June we released the resulting 841 tadpoles into the reservoir. We also moved frogs from below the Bear Gulch Dam and inside the Bear Gulch Cave back up to the reservoir. During a survey of the reservoir in September we counted 20 two-year-olds, seven one-year-olds, and 427 newly transformed frogs. The large number of young from this year suggests that the two-year-old frogs may have already begun breeding at the reservoir.

When we initiated this project, we set our measure of success at more than four egg masses or twenty adults at the reservoir observed in spring. In 2004 we reached that goal, with five egg masses in the Bear Gulch Reservoir. In Fall 2004 we counted 485 young frogs plus 15 older frogs at the reservoir. If the newly established population continues to thrive and reproduce as it is now doing, we expect to have a self-sustaining population of California red-legged frogs at the Bear Gulch Reservoir for many years to come. And it will not be surprising if some of their offspring migrate downstream to re-populate Bear Gulch and additional sections of Chalone Creek.  As an exciting prelude to this, a male red-legged frog was heard calling at Bear Gulch Headquarters in Spring 2004, perhaps for the first time in at least a couple decades.

California Red-Legged Frogs are listed as a Threatened Species under the Endangered Species act. It is illegal to harass or harm them in any way. Approaching so closely that they jump is a form of harassment. Catching them not only disturbs them, but may also cause serious injury. If you hike to the Bear Gulch Reservoir and are fortunate enough to see these frogs, please enjoy them from a distance. With binoculars you can get a great up-close view while letting them go about their lives undisturbed. Please share any interesting frog-watching observations with us.


Butterflies are a wonderful reflection of the surrounding landscape. On a well-manicured lawn they are scarce. In a vacant lot where plants are more diverse but nature has been severely disturbed, you may find a few more. In a butterfly garden where the gardener has taken care to choose a variety of plants that will satisfy the needs of thirsty butterflies as well as hungry caterpillars, the diversity of butterflies often reflects that care. But the best places to see lots of butterflies of many different kinds are places where people have taken care to leave nature well enough alone.

Pinnacles National Monument is just such a place. Although it is only about five miles wide and seven miles long, most of the land is undisturbed wilderness that supports a great diversity of living things. Sixty-eight different species of butterflies have been recorded at Pinnacles. About 35 species are common enough that you are likely to see them if you visit the right habitat at the right time. About a dozen are so abundant that you may see hundreds of them on a visit.

The Pinnacles National Monument Butterfly Checklist shows the number of butterflies of each species you can expect to see in a few hours for each month of the year and in five different habitats. Once you know the right time and place to look for butterflies, you can get even more specific by also looking for their host plants (the plants on which butterflies lay eggs and caterpillars feed) and nectar plants (the favorite flowers from which adult butterflies drink nectar).

For example, let's say you are visiting Pinnacles in July and you want to see a Sylvan Hairstreak. The Checklist says that in riparian (streamside) habitat in July you can expect to see more than 20, and that their host plant is willow and their favorite nectar plant is milkweed. Since willows don't grow in all riparian habitats, on the advice of a Park Ranger you take the Old Pinnacles Trail. Along the trail you notice three different species of willow. On two of the species you find nothing. But as you approach the shrubby, smooth-leaved species, you see several small gray butterflies zip off from the tips of the leaves and then return. As you continue, you scare up several Sylvan Hairstreaks from each of these willows that you pass. Then you spot a milkweed with half a dozen Sylvan Hairstreaks sipping nectar from its flowers. Mission accomplished, you've had a fine hike and no doubt seen many other butterflies along the way.

Here are some tips to keep in mind when seeking butterflies. Butterflies are creatures of the sun. They are most active from 9 a.m. to 4 p.m., and are seldom out in the cold, rain, or wind. Some good butterfly spots include hilltops, moist areas, open patches of ground, and flowers. Certain species of flowers attract many more butterflies than others. In the summer and fall the few flowers in bloom will often draw butterflies from great distances. Some particularly good butterfly flowers at Pinnacles include wallflower, California buckeye, thistles, California buckwheat, wooly yerba santa, summer mustard, milkweeds, vinegar weed, exotic mints, shrubby butterweed, coyote brush, and heliotrope.

The number one threat to butterflies everywhere is loss of habitat. A decline in a particular butterfly species is often a direct reflection of a decline in habitat for its host plant. By protecting natural processes and habitats across the wilderness landscape, Pinnacles goes a long way toward protecting butterflies. (One part of that protection is to prohibit collecting butterflies, wildflowers, or anything else within the Monument.) In order to keep track of how butterflies are doing over the long term, the park conducts an annual Pinnacles National Monument Butterfly Count. The information from this count can be compared to data from previous years to help us detect species declines. The park can also look at other places that conduct similar counts to see whether the declines are widespread or restricted only to Pinnacles and then look for causes and begin to remedy them.

The park's goal is to ensure that visitors to Pinnacles National Monument have the same opportunity to see Sylvan Hairstreaks and other butterflies regardless of whether it's the year 2004 or 4002. If you would like to help the park achieve this goal, please report any unusual butterfly sightings, and join them for the annual Butterfly Count.


Bats at Pinnacles find refuge in the caves, cliffs, and trees. There is currently a colony of Townsend's Big-eared Bats in the Bear Gulch Cave and a colony of the Western Mastiff bat in the Balconies cave area.

Out of the 23 species of bats in California, 14 species are known to occur within Pinnacles National Monument. These bats are:

Western Pipstrelle (Pipistellus hesperus)
Western Red Bat (Lasiurus blossevilii)
Hoary Bat (Laisiurus cinerius)
Townsend's Big-eared Bat (Corynorhinus townsendii)
Pallid Bat (Antrozous pallidus)
Big Brown Bat (Eptesicus fuscus)
California Myotis (Myotis californicus)
Small footed Myotis (Myotis ciliolabrum)
Long eared Myotis (Myotis evotis)
Fringed Myotis (Myotis thysanodes)
Long-legged Myotis (Myotis volans)
Yuma Myotis (Myotis yumanensis)
Brazilian Free-tailed Bat (Tadarida brasiliensis)
Western Mastiff Bat (Eumops perotis)

All of the fourteen species at Pinnacles and forty-one of the forty-four North American bats eat insects, spiders, and their kin. Three species eat fruit or nectar. There are only three species of vampire bats -- they live in South America and feed on birds and mammals.

Bat Facts
"Blind as a bat."
Bats not only "see" the world with echolocation, but they have good eyesight. Some bats find their food exclusively with sight and they can see better than humans in dim light.

"They get tangled in your hair."
Bats can be very curious. They will often circle around something or someone new in their air space to take a second look.

"Bats are flying mice."
Bats are actually more closely related to primates than to rodents. Most bats give birth to only one "pup" per year which they feed milk. Other than humans, bats are the longest lived mammals in North America; one little brown bat (Myotis lucifugus) is at least 34 years old.

"Bats are just pests."
Bats are important insect predators, pollinators, and seed dispersers. Bats live on all continents except Antarctica and are on the decline worldwide.

"All bats carry rabies."
Bats are not "carriers" of rabies; less than 1% of bats contracts rabies and dies. Bats will bite in self defense. Avoid handling them as well as other wildlife.


Compared to the rest of Central California, Pinnacles is home to a high diversity of reptiles: eight lizards, fourteen snakes, and one turtle. Species most commonly encountered include the western whiptail, coast horned lizard, western fence lizard, common garter snake, striped racer, gopher snake and western rattlesnake. Some species, such as sharp-tailed snake, are most active in the cool, wet months. Others, such as Gilbert’s skink and alligator lizard, are most likely to be seen as the days begin to warm up in April and May. The striped racer and western whiptail prefer the hottest days. And some, such as the western fence lizard and side-blotched lizard, can be seen during all but the hottest and coldest weeks of the year. Western pond turtles are uncommon and elusive, so consider yourself lucky if you see one here. Another elusive reptile is the desert night lizard. It is said to spend almost its entire life in a single decaying log. However, it is sometimes possible to see one at night near the porch light at the Bear Gulch Visitor Center. It lives in the cracks in the building, making occasional forays out to eat insects attracted by the light.

Although you may be tempted to capture reptiles in order to get a closer look at them, this is prohibited here. Binoculars are a great way to get an up-close look at an animal doing what it naturally does, rather than doing what many reptiles do when captured: biting you, defecating on you, or dropping their tails.

Turning over rocks and logs to look for animals is also prohibited, and for good reason. Even the most careful turning over of a rock or log and returning it to its original position disturbs the habitat and may scare the animal away from a perfectly good home. 200,000 people visit Pinnacles each year. If only one in a thousand people did it, that would be 200 people, meaning that rocks and logs could get turned over just about every weekend. The reptiles living there would likely move farther from the trail. Even if they survived this disruption, people on the trail would be less likely to see them. Instead, if you spend enough time looking, many animals that usually hide under rocks and logs can also be seen out in the open.


An autumn visit to Pinnacles National Monument is often rewarded with a sighting of one our most fascinating creatures, the tarantula. September and October are the prime months to see male tarantulas ambling resolutely day and night in search of mates. They investigate every potential burrow, looking for a female ready to lay eggs in her specially prepared nest.

Why don't you see tarantulas during the rest of the year? They are always in the park, but they are usually much more secretive. They spend the day in their burrows, emerging to hunt only at night. At any time of year, if you look carefully on the ground for small holes lined with silk, you might see a tarantula looking back at you! You'd be surprised how small a hole a tarantula can fit into.

Tarantula X-ing
Tarantulas are commonly seen crossing roads. Please obey posted speed limits and watch the road to avoid running over tarantulas and other wildlife.

Part of the Food Web
Tarantulas eat a variety of insects and other invertebrates, and possibly lizards, snakes, and small rodents. They bite their prey, injecting it with digestive juices. Then they mash it with their strong jaws, and drink the liquid. After a large meal, a tarantula may wait several months before feeding again. Tarantulas are in turn eaten by lizards, snakes, birds, and tarantula hawks.

Tarantula Hawk
If you think the way a tarantula feeds is gruesome, wait till you hear about the tarantula hawk. Nearly the size of a hummingbird, it is our largest member of the spider wasp family. It is stunning with its shiny blue-black body and smoky orange wings. You can often see them in summer and fall visiting flowers.

When the female tarantula hawk is ready to lay her eggs, she leaves the flowers behind and goes on the hunt for a tarantula. Upon finding one, she paralyzes it with a sting. Even though the tarantula is several times her own weight, she drags it to a hole, lays her eggs on it, and buries it. The eggs soon hatch into wasp larvae which slowly devour the paralyzed tarantula alive, from the inside out.

Self Defense
If provoked, the tarantula may inflict a painful bite, about like a bee sting. (The tarantula hawk's sting is much more painful.) However, the tarantula has a rather gentle nature, and rarely uses its fangs except to catch prey. When alarmed, it may raise its front legs and its abdomen to look aggressive. It may also release stinging hairs from its abdomen. These hairs irritate the skin of an attacker by digging themselves in with hundreds of tiny hooks.

Tarantula Web
A tarantula spins silk, but not in the form of a web for catching food. Instead, the silk is used to line the burrow, and by the female to line the nest and cover the eggs.

Walking up Walls
Web-spinning spiders have three claws, the middle one being used for grasping the web. In tarantulas, the middle claw is replaced by a dense pad of hairs. Each of these hairs splits into hundreds of microscopic branches, called "end feet." The combined surface effects of all the end feet allow the tarantula to walk on walls and even ceilings.

Spider Senses
Tarantulas have eight eyes, although they probably can't see very well. They have no ears, although they have thousands of fine body hairs which allow them to feel the vibrations of passing prey. They taste with special "taste hairs" near the feet and around the mouth. They probably smell with pits on top of the feet.

Life Span
Tarantulas reach maturity at about 10 years. Males die within a year of mating, and are sometimes eaten by the female before mating. Females may live over 20 years.

What's in a Name?

What ho! What ho! This fellow is dancing mad! He hath been bitten by the Tarantula.
- Edgar Allan Poe

"Tarantula" was the name originally given to the southern European wolf spider (Lycosa tarentula) and referred to the town of Taranto, Italy. It was believed that the bite of this spider would cause the disease of tarantism, the symptoms being uncontrolled weeping and jumping about. The victim would finally go into a wild dance called the Tarentella. This dance is now a popular Italian folk form and has inspired several famous composers to write classical versions. Scientists have not studied the tarantulas of California well enough to be able to give the tarantula found at Pinnacles a specific scientific name. It is most likely in the genus Aphonopelma. Do you know anybody who would like to study our tarantulas?

Boy or Girl?
Most of the tarantulas you encounter are males out wandering in search of females. If you are lucky enough to meet a tarantula face-to-face, look for the tibial spur on each front leg behind the "knee." Only males have this claw-like appendage.

Other Spiders at Pinnacles
We know very little about the spiders of Pinnacles. There are undoubtedly hundreds of species, many of them undescribed. Plus, there are many spider relatives here: ticks, mites, scorpions, sun scorpions, pseudoscorpions, and harvestmen. Some of the more conspicuous spiders at Pinnacles are:

Hairless tarantula: This spider is about half the size of the more commonly seen tarantula. It lacks stinging hairs, and it is quite aggressive.

Green lynx: Look for this spider in the fall on small flowering shrubs, where it catches insects visiting the flowers. It can be very hard to see, but once you find one, you will often find more nearby. Also look for its white egg sacs.

Black widow: This well-known, highly poisonous spider advertises "danger" with the red hourglass on its underside. Its web is exceptionally strong.

Crab spiders: Look carefully on flowers for these spiders. They hold their long front legs wide open, waiting to snatch their flower-visiting prey.

Diguetid spiders: Although you may never see one of these spiders, their webs are quite conspicuous in California buckwheat shrubs. Look for a vertical tube filled with debris, above a flat cone of threads.

For more information:
American Tarantula Society


Raptors – birds of prey – are a common and beautiful sight at Pinnacles National Monument, especially during the breeding season from January to August. Raptors are specialized hunters, with powerful beaks and talons for tearing apart prey, and exceptional eyesight for locating food from great distances. Most raptors can see even small birds like swallows clearly from almost 2 miles away, thanks to their telescopic vision.

Over 20 species of raptors have been documented at the park, with 10 species nesting on a yearly basis, including the highest density of nesting prairie falcons in the country. The geography of the park provides raptors with ideal nesting sites, both on the inaccessible cliffs and rock formations used by prairie falcons, golden eagles, red-tailed hawks, and American kestrels, and on the oaks and pines along the riparian corridors used by Cooper’s hawks, sharp-shinned hawks, and red-shouldered hawks. The location of the park also provides raptors with plentiful food sources. Small raptors like kestrels and sharp-shinned hawks primarily eat animals as small as grasshoppers and as large as lizards and mice; these prey items are readily available within the park boundaries. Larger raptors like prairie falcons, red-tailed hawks, and golden eagles feed on larger prey, from small birds to larger rodents including squirrels and rabbits. These are readily available in the agricultural areas surrounding the park, and often falcons and eagles can be seen soaring beyond the park boundaries in search of food.

Diurnal raptors – birds of prey active during the day – make up only a part of the assemblage of birds of prey found at Pinnacles. These include the falcons, hawks, and eagles listed above. As twilight fades into night, owls – the nocturnal raptors of the park – become active. Owls have well-developed night vision and hearing, as well as feathers specially adapted for silent flight, to aid them in hunting for rodents and other birds at night. At Pinnacles, owls are most often heard rather than seen. Great-horned owls hoot loudly in the spring near the reservoir and Balconies, and western screech-owls vocalize from near the Bear Gulch Visitor Center with a whistling hoot that increases in speed as the birds call. Occasionally, long-eared owls call from the riparian corridors along Chalone Creek and in the Bench area; listen for a monotonous, single note repeated slowly over and over.


Forty-nine mammalian species, aside from humans, are known to occur within Pinnacles National Monument. Those often seen and enjoyed by visitors and staff include: black-tailed deer, bobcat, gray fox, raccoon, jackrabbit, brush rabbit, ground squirrel, chipmunk, and several kinds of bat. These animals are reported regularly because they are either easy to see or charismatic. Badgers, coyotes, a wide variety of rodents, and mountain lions inhabit the Monument, but are not commonly seen. The infrequent sighting of some of the mammals in the Monument points to a difficulty in studying them: extensive monitoring is required to determine baseline data on all mammalian species within Pinnacles. This work will be ongoing for many years, and we will keep you informed about it. For example, we are currently conducting a small mammal survey, which may soon be available on our web pages.

The mammals at Pinnacles belong to the following orders: Marsupialia (1), Insectivora (3), Chiroptera (16), Lagomorpha (3), Rodentia (15),Carnivora (9) and Artiodactyla (2). Included in these are three mammals which have been introduced to Pinnacles -- the house mouse, opossum, and feral pig. The house mouse (Mus musculus) and opossum(Didelphis virginiana) are rare and not considered threatening to Pinnacles’ native ecosystems. Feral pigs (Sus scrofa), on the other hand, are abundant within the Monument and cause extensive damage to the native vegetation. Based on several years of research, a decision was made to construct a fence around the Monument’s perimeter. Pigs within the fence will be removed, and new pig incursions will be prevented.


The moths of Pinnacles range in size from smaller than a gnat to larger than a hummingbird. Most fly at night, but a fair number are active only in daylight. Most are drab in color, at least when settled, but many have brightly colored hind wings that are evident in flight. Even most of the drab-colored moths have intricate patterns on their wings. The peak season for moths here is late spring, but they can be found in any month of the year. On a calm, warm night with no moon, dozens of species can be seen at a single light, along with other insects that are attracted to light, and predators such as bats, salamanders, toads, night lizards, and spiders.

How many different kinds of moths would you guess are found at Pinnacles National Monument? We don’t know the answer to that question, but we’re working on it. One way to estimate the number of moths in our part of the world is to multiply the number of butterflies by 15. We have 68 known species of butterflies, which yields an estimate of about 1,000 species of moths. We started collecting moths in September 2002. We collect at black lights, porch lights, and with nets during the day. We estimate that using these methods we will find about 75% of the moth species here.

Why study moths? First of all, we are given the mission to protect our natural resources, which is difficult if we don’t specifically know what those resources are. Once we have a name for a moth, we can consult publications and moth experts to get information that might help us protect it. Also, during our study we will collect information that will add to the body of knowledge about moths, and we are likely to find some new species not previously known to science.

One important reason to study moths is that they are an integral part of the Pinnacles ecosystem. We can’t protect the whole without knowing how to protect its parts. For every adult moth you see, there are many more moth caterpillars out there munching on plants. Moth caterpillars convert more plant material into food for predators than any other group of animals. Because they are a major component of the food web, much of the wildlife here depends on them either directly or indirectly.


Pinnacles National Monument has been a part of the California Condor Recovery Program since 2003. In partnership with the Ventana Wildlife Society, a central-California non-profit organization, we have released 19 juvenile condors into the wild. Each condor is monitored carefully after its release to increase its chances of survival. Biologists ensure that they choose safe roosting sites, find the feeding areas, and stay away from hazards such as lead-contaminated food and power poles.

Information about Pinnacles Condors

View images of the Pinnacles free-flying condors as they perch near one of their feeding sites.

Updates on Condors
Thirteen condors are flying free over Pinnacles National Monument and beyond. Read updates on the condors and the Pinnacles program.

Where Can I See a Condor?
If you're coming to Pinnacles and would like to catch a glimpse of this rare bird, this information will help you decide where to look.

Milestones of the Condor Program at Pinnacles
Read about the major events in the condor program at Pinnacles.

Current Population StatisticsAn overview of the California condor population, compiled by the California Department of Fish and Game.

Closure Notice
An area of Pinnacles National Monument is closed to the public to protect the condor facility and feeding areas. No hiking trails are affected by this closure.

Should I report a condor sighting?
Any condor sightings outside the Pinnacles boundaries will help us track them. If you see a condor engaging in potentially dangerous behaviors such as feeding, approaching humans, or perching on manmade structures, please report the sighting as soon as possible.

Please view condors from a distance of at least 100 feet and never approach or try to feed them.

Wild Pigs

Wild pigs (Sus scrofa) were first observed at Pinnacles National Monument in the late 1960s. In 1769, Spanish explorers introduced domestic swine to California as a food source and to clear land. Allowed to roam freely, these domesticated pigs inhabited various parts of California as feral or wild hogs. The European wild boar was imported to Monterey County in 1925 for hunting purposes, and has successfully interbred with feral hogs already established. These hybrids have spread throughout much of California, both naturally and with the aid of hunters and landowners. The wild pigs that have invaded Pinnacles are a combination of European wild boars, feral hogs, and hybrids of the boar and hog. Wild pigs are not native to California. They are considered exotic species.

Wild pigs consume an abundance of plant matter including acorns, grasses, forbs, berries, roots, and bulbs. They also feed on ground dwelling insects, worms, reptiles, amphibians, fish, small mammals, and carrion including other pigs. Wild pigs spend much of their time rooting or digging with their noses in search of these food items.

Pigs tend to prefer cooler more shaded areas, do not tolerate heat well, and must have a constant water supply in order to survive. They are primarily nocturnal in the hotter months and prefer oak woodlands along streams and chaparral habitat. Here they forage for food, wallow in mud and water, and seek shelter from the sun.

Wild pigs have a high reproductive rate. If there is a sufficient supply of food to accommodate a sow, she can have two litters a year. Litters range from 4-14 piglets. Pigs can adapt to harsh environments and have few natural predators, making them difficult to control.

Wild Pig Impacts

Because wild pigs are not native to Pinnacles National Monument, their behavior alters the natural processes that occur in the park. This behavior has been shown to have a negative impact on the plants, animals, and soil.


Rooting by pigs disturbs natural plant communities by destroying native species. The soil is uplifted by this rooting behavior, causing it to dry in the heat of summer. Plants have to work harder to find water and their chances for survival are decreased. Areas that once had native plants become susceptible to the establishment of exotic plants. These exotic species compete with native plants for available space, ultimately compromising the natural order of the plant community. Pigs also consume large amounts of fruits, nuts, and seeds, which decreases the ability of new plants to germinate.


Pigs compete with deer and other wildlife for acorns, insects, and other food sources. Pigs also prey on a number of animals and insects, directly threatening their survival. Besides competing with and preying upon animals, wild pigs have the potential to infect animals, as well as humans with a number of diseases and parasites. Rooting behavior also adversely affects the habitat of ground dwelling animals such as amphibians, reptiles, mammals, and ground nesting birds.

Soil Erosion

Pig rooting significantly increases the rate of erosion. Pigs root near stream banks causing the soil to loosen and wash away during rains. When soils wash into streams and creeks the water quality is decreased. Poor water quality has a negative impact on many aquatic animals including the threatened California red-legged frog.

Management of Wild Pigs

The National Park Service has a policy of conserving, protecting, and restoring native plants and animals. Park managers at Pinnacles National Monument are required to control or eradicate non-native species that have a negative impact on its resources. In 1984, the Monument staff had considerable concerns about the increasing number of wild pigs and the destruction they were causing to the Park. After several years of research and testing, the Monument decided to construct a fence around the perimeter that would prevent pigs from invading the park.

The fence is designed to prevent pigs from rooting underneath, while allowing animals of various sizes to pass through, or jump over. Completed in 2003, the fence surrounds more than 14,000 acres of parkland and stretches a distance of roughly 24 miles.

Upon completion of the pig-proof fence, the Monument contracted wildlife biologists from the Institute for Wildlife Studies (IWS) to eradicate exotic pigs within the fence-enclosure. Using ground-hunting methods, trained dogs, and traps, and subsequently monitoring for pig sign, IWS staff deemed the fence-enclosed area of the Park free of pigs in June 2006.

Park staff will continue to regularly patrol the fence to ensure that pigs cannot immigrate due to structural instabilities. If damage to the fence occurs due to natural and/or unforeseen circumstances, routine maintenance activities will be conducted and any necessary repairs made. If pigs do enter the fenced-enclosed area of the Monument, measures will be taken to eliminate pigs from within. Now that exotic pigs have been eliminated from the core area of the Park, routine monitoring and maintenance measures are crucial to maintaining a pig-free environment.

One of the goals of PinnaclesNational Monument is to maintain this pig-free environment in perpetuity within the fenced portion of the Park. The unique and wondrous diversity of flora and fauna that has evolved here depends upon this goal.


As their name implies, woodpeckers are very effective at hammering away at the woody trunks of trees. They have long, sharp bills, powerful heads and neck muscles, stiff tails for balancing on the sides of tree trunks, and large toes with sharp talons for gripping bark and woody surfaces. Pinnacles has 6 species of woodpeckers that live at the park year-round. These are acorn woodpeckers, downy woodpeckers, hairy woodpeckers, red-breasted sapsuckers, northern flickers, and Nuttall’s woodpeckers. Another woodpecker species – Lewis’ woodpecker – is rarely seen as it migrates through the park.

Although the woodpecker species at Pinnacles may look similar, they have surprisingly different methods for feeding. Downy, hairy, and Nuttall’s woodpeckers primarily eat insects, and have exceptionally long tongues for extracting prey from holes in trees. In fact, the tongues are so long that they wrap around the skulls of the woodpeckers when they are not in use. Hairy, downy, and Nuttall’s woodpeckers also have barbs on the ends of their tongues and very sticky saliva that help the birds to retain their insect prey as they are pulling them out of holes in trees.

Red-breasted sapsuckers, as their name implies, feed on sap from oaks in the park. Their tongues are not extremely long, but have specialized hairs on the tips. Sapsuckers drill into the sides of oaks throughout the park, creating sap wells that drip from the trees. The woodpeckers then use the hairs on their tongues to capture the sap through capillary action; in other words, they “suck” the sap from the wells. Creating the sap wells serves another function for the sapsuckers: the wells attract ants that feed on the sap. The sapsuckers wait for a large concentration of ants to gather at the sap wells, then fly to the sites to feed on the insects. The sap wells have the additional benefit of providing a food source for many other bird species in the park.

Acorn woodpeckers are the most visible woodpecker species at the park; most visitors will quickly notice their antics and cackling, “wheka wheka” calls in the pine trees near the Bear Gulch and Chaparral Visitor Centers. Acorn woodpeckers also have one of the most interesting strategies for ensuring a food source for themselves. These woodpeckers hoard large amounts of acorns and other nuts in “granaries,” 1-2 snags (standing remains of dead trees) or pines located centrally in family territories. Up to 50,000 acorns may be stored in a single tree. Acorn woodpeckers aggressively defend their territories, and hammer the nuts tightly into holes in the trees to make it difficult for potential robbers including Steller’s and scrub jays to remove the acorns without being detected, or to remove them from the holes at all. The granaries provide an essential source of surplus food to the acorn woodpeckers, especially during the dry summer and fall seasons at Pinnacles when other food supplies are scarce. Visitors to the park should look for the woodpeckers’ granaries near the visitor centers and trailheads. Two large gray pines near the Bear Gulch Visitor Center bathrooms are used by the acorn woodpeckers as granaries, and give a sense of how much food these birds are actually hoarding year after year.

Insects, Spiders, Centipedes, and Millipedes

Although often overlooked, invertebrates comprise tens of thousands of wildlife species at Pinnacles. Their lack of bones, teeth, fur, and feathers may make them seem primitive, but don't be fooled. In many cases their life histories are just as complex as those of larger animals, and often much more bizarre. And they are usually much easier to find and observe than larger wildlife.

An inventory of bees conducted in the late 1990's found nearly 400 species of bees at Pinnacles. This is the highest known bee diversity per unit area of any place on earth. The diversity of butterflies here is not nearly as high (68 species), but in the right time and place it is possible to see thousands of individual butterflies in a single day. A moth inventory is currently in progress, with the number of moth species expected to be around 1,000. Samples are still being analyzed from an inventory of aquatic macroinvertebrates, but 40 species of dragonflies and damselflies are known to inhabit Pinnacles' waters. Most other invertebrate groups remain largely unstudied.

Two invertebrates found at Pinnacles are endemic to our area, being found elsewhere rarely or not at all. The Pinnacles shieldback katydid (Idiostatus kathleenae) is about 2 cm long, wingless, and dark gray in color. It is active at night, feeding on the flowers of California buckwheat and other plants. The Pinnacles riffle beetle (Optioservus canus) is a tiny (2 mm) brown beetle that lives in fast-flowing sections of Chalone Creek.

The most common way to study invertebrates is to capture and kill them. While this method may be appropriate under many circumstances, a visit to Pinnacles is not one of them. In order to protect the wildlife at Pinnacles, collecting is prohibited without a scientific collecting permit issued by the monument. A great tool for getting a good look at invertebrates going about their lives is a pair of close-focus binoculars. With 8X binoculars, from eight feet away you will have a view as if you were only one foot away! That's plenty close for watching a bee gather pollen, a butterfly sip nectar, or a tarantula wasp sting and drag off a tarantula.


Due to the intermittent nature of Pinnacles’ streams, the three-spined stickleback is the only native fish here. A predatory feeder, it eats predominately aquatic insects, and reaches three inches in length when full-grown. The stickleback is often observed along the Bear Gulch and South Wilderness Trails. Other fish species may swim upstream into the Monument from the Salinas River during floods, but they generally do not survive through the summer.

In the early 1980’s, non-native catfish inhabited the reservoir. This population was eradicated in the mid-1980’s by draining the reservoir and electroshocking the remaining fish. In the mid-1990’s non-native green sunfish infiltrated Monument streams. They were considered a major threat to red-legged frogs, and were removed by electroshocking. Currently the mosquitofish is the only non-native fish species here. Although its presence has a minor impact on red-legged frogs, eradicating it is currently impractical.

For more information on the Exotic Green Sunfish Removal Project and past exotic fish infestations, see the

1999 Exotic Fish Removal Report.

Related Information:
Fish Checklist for Pinnacles National Monument

Exotic Species

Over the past 200 years, thousands of foreign plant and animal species have become established in the United States. About one in seven has become invasive. The invasive species typically have high reproductive rates, disperse easily, and can tolerate a wide range of environmental conditions. Often, they lack predators in their new environments. As a result, invasives may outcompete native flora and fauna for biological niches carved out over millennia.

Some non-native species, intentionally introduced for beneficial purposes, later turn out to be invasive. Examples include saltcedar, which was introduced for erosion control, or the feral pigs here at Pinnacles National Monument. 138 billion dollars is the price-tag put by Cornell University researchers on the invasive species-induced costs of ecosystem damages, reduced crop yields, control efforts and lost forest products in the United States alone. The ecological costs of invasive species are also staggering. They eat, outcompete, and hybridize with native species, spread diseases, and eliminate or change native habitats. In the United States, 400 of the 958 species listed as threatened or endangered under the Endangered Species Act are at risk primarily because of competition with and predation by non-indigenous species. In some areas of the world, this proportion is much higher. In fact, the impact of invasive species is second only to direct habitat destruction, such as clearcutting, among the causes of extinction. The undoing is not limited to habitats and non-humans; we are also losing people, languages and cultures.

The land of Pinnacles National Monument began to be protected in the early 1900s. That does not mean that the land is unaltered, but that it has been buffered from invasive species. The Monument’s harsh climate, with large daily temperature fluctuations and hot, dry summers also buffers Pinnacles from invasives, because fewer invasives are able to thrive here. Pinnacles National Monument is special today in part due to its relatively high proportion of native plants and animals, and comparatively undisturbed land. We seek to preserve the health of the Monument’s habitats by controlling exotic plants and feral pigs, as detailed in the highlights above.

Sensitive Species

While all native wildlife species at Pinnacles National Monument are protected, some warrant special attention. In many cases they have been listed by other agencies as Endangered, Threatened, or Species of Special Concern. Species endemic to the Pinnacles area are also listed here because even though they may not currently be in trouble, much of their known range falls within our boundaries.

  Common Name Scientific Name Status
Insects Pinnacles shield-back katydid Idiostatus kathleenae 3
  Pinnacles riffle beetle Optioservus canus 3
Fish Sacramento Perch Archoplites interruptus  CSC*2
Amphibians Gabilan slender salamander Batrachoseps gavilanensis 3
  California tiger salamander Ambystoma californiense FT
  Western spadefoot Spea hammondii CSC 2
  California red-legged frog Rana aurora draytonii  FT
  Foothill yellow-legged frog Rana boylii  CSC*2
Reptiles Southwestern pond turtle Clemmys marmorata pallida CSC*
  California horned lizard Phrynosoma coronatum frontale CSC
  Silvery legless lizard Anniella pulchra pulchra  CSC
  San Joaquin coachwhip Masticophis flagellum ruddocki  CSC
  Two-striped garter snake Thamnophis hammondii CSC 2
Birds California condor Gymnogyps californicus SE/FE 2
  Cooper’s hawk Accipiter cooperi  CSC
  Sharp-shinned hawk Accipiter straitus CSC
  Golden eagle Aquila chrysaetos CSC
  White-tailed kite Elanus leucurus CSC
  Prairie falcon Falco mexicanus CSC
  Peregrine falcon Falco peregrinus 2
  Long-eared owl Asio otus CSC
  Yellow-breasted chat Icteria virens  CSC
Mammals Pallid bat Antrozous pallidus CSC
  Townsend’s big-eared bat Corynorhinus t. townsendii  CSC*
  Western mastiff bat Eumops perotis californicus CSC*
  Big-eared kangaroo rat Dipodomys elephantinus CSC*
  American badger Taxidea taxus CSC


CSC =California Species of Special Concern
F = Federal 
S = State
E =Endangered
T = Threatened
* = Category 1 and 2 species before revoked in 1996
1 = occurs around PINN and has habitat within PINN, but has not been confirmed
2 = historically occurred in PINN, but is believed to be locally extirpated
3 = endemic to Pinnacles and surrounding areas

Keep Wildlife Wild

Feeding animals at Pinnacles National Monument is not only unhealthy for park wildlife, it can also be dangerous for humans. Please avoid the temptation to feed park animals.

Animals that are fed by humans may become aggressive. Each year at Pinnacles Campground, there have been injuries caused by raccoons that have become accustomed to getting handouts from campers. Other animals that can often be spotted begging are squirrels, magpies, and jays.

Nocturnal animals roam the campground in the evening hours, looking for food that hasn't been stowed properly. Keep your food and all scented items in your vehicle where pigs and raccoons can't get at them.

In campsites and at trailheads and picnic areas, squirrels will often approach people to beg for food. Squirrels can pose a serious threat to humans. They can transmit diseases such as rabies and bubonic plague, even if you don't make contact with them.

If an animal approaches you, act immediately to scare it away. Keep your food and scented items within arm's reach. When you're done with them, stow them safely in your vehicle. If you're camping, keep a clean campsite, and never leave trash out at night.

Each park faces different challenges with keeping human food away from wildlife. At any camping area, be sure to ask about food storage regulations when you check into your site.

If you feed wildlife, intentionally or unintentionally, you could be cited under 36 CFR 2.10(d) or 2.2(a)(2).

Human food is harmful to wildlife, and feeding park animals is dangerous to humans. Please enjoy the animals of Pinnacles from a distance.

The faults within the Pinnacles National Monument mark distinct boundaries in geology. The Pinnacles Fault juxtaposes granitic basement rock west of the fault and the Pinnacles Volcanic Formation east of the fault. The Chalone Creek fault juxtaposes the Pinnacles Volcanic Formation west of the fault and the Temblor Fanglomerates east of the fault.

The granitic basement is the Santa Lucia Granite and Granodiorite. These granites formed when masses of molten lava slowly cooled as they rose through the earth's crust to a point where they completely solidified. A slow cooling process allows individual crystals to grow fairly large. Subsequent uplift from faulting and erosion of overlying material exposed these rocks at the earth's surface. These are the oldest rocks in the park, 78-100 million years old. They form the basement upon which the rest of the rocks at the Monument lie.

The Pinnacles Volcanic Formation formed approximately 23 million years ago as it was extruded and deposited atop the granitic basement. The magma that was the source of all the volcanics was rhyolitic in origin. The formation consists of rocks such as banded and massive rhyolite, some andesites and dacites and various pyroclastic units.

The High Peaks consists of a relatively strong, well-consolidated breccia. The layers of breccias are thought to have formed as the result of material slumping off the sides of the volcano near the vents causing large landslides. The volcano was likely near water and the landslides traveled as massive turbidity currents under water that spread the material considerable distances until coming to rest near distant edges of the volcano. Volcanic ash and rhyolitic lava flows are interlayered with these breccias. Subsequent burial and compaction hardened these layers into the consolidated rock we see today. Recent faulting, fracturing and erosion have sculpted these rock layers into vertical cliffs and spires sometimes several hundred feet high.

The Temblor Formation east of the Chalone Creek Fault is a fanglomerate unit (conglomerates deposited in an alluvial fan setting) composed of granitic and to a lesser extent volcanic detritus shed from the Santa Lucia granitic basement and the Pinnacles Volcanics.


The pinnacles themselves are the remnants of a Miocene volcano that is in an advanced stage of decomposition. Approximately 23 million years ago, rhyolitic magma and other flows were forced to the surface through fissures in a basement of quartz diorite and granite. Later activity developed central vents, and explosions from these vents built up a vast thickness of pyroclastics above the earlier lavas. The action of erosion, the work of water and wind on these pyroclastics, has given rise to the unusual and scenic effects for which Pinnacles is famous.

Located near the boundary of the Pacific Plate and the North American Plate, Pinnacles National Monument is an excellent example of tectonic plate movement. The Pinnacles Rocks are believed to have originated in the Neenach Volcano, near present-day Lancaster, California. The unique breccias of Pinnacles are only found elsewhere in the Neenach Formation, some 195 miles (314 km) southeast. The displacement of the Pinnacles from its point of origin is a testament to the longevity and importance of the San Andreas Fault, which once split the original volcano. The right lateral movement of this giant transform fault has carried the Pinnacles north at a rate of approximately 0.59 inches (1.5 cm) per year.

Three large faults (Miner's Gulch, Pinnacles, and Chalone Creek) occur within or near the Monument, besides a number of smaller faults and fractures. The Chalone Creek Fault located within the Monument and still active, runs parallel to the major drainage along the east side of the Monument and is thought to mark the position of the San Andreas Fault in the Miocene - at the time the Neenach Volcano erupted. Today, the San Andreas Fault has shifted its location 4 miles (6 kilometers) to the east of the Monument. The large faults of the Pinnacles area are roughly parallel to this master fracture and were probably caused by major movements of this important fault. Complex fault movement has buried the Pinnacle volcanics for much of their northbound journey, only recently unearthing these easily weathered and erodable rocks. This history of faulting and earthquakes has also created deep, narrow gorges where huge boulders have toppled from higher formations. These boulders, wedged at various heights above the canyon floors, create the Bear Gulch and Balconies talus caves.

Small to moderate earthquakes are frequently felt within the Monument. Seismic activity continues to be monitored by the United States Geological Survey (USGS). There is a seismometer along the Chalone Creek Fault and a corresponding seismograph in the Bear Gulch Visitor Center which provides a continuous record of seismic activity. Visitors are often able to see the seismograph to confirm their suspicion of previously felt ground movement. The purpose of continued monitoring is to learn more about earthquake phenomena along the San Andreas Fault. The information provides the Monument staff with data to illustrate and interpret the natural processes still shaping the Pinnacles area.

Expression of seismic activity abounds. Streams show characteristic offsets as they cross fault bounds. Valley bottoms and terraces are evidence of localized uplift; the nearby town of Hollister contains several sidewalks torn by fault creep. Because this segment of the San Andreas Fault is a “creeping” segment as opposed to a “slipping” segment, major or severe earthquakes are considered less frequent along it. Still, moderately intense ground shaking is likely in the near future whether it originates from faults nearby or locked fault segments far north or south.  A study in the Bear Gulch Cave, initiated due to safety concerns following the 1989 Loma Prieta earthquake, has detected no movement of boulders following moderate earthquakes.

Cave / Karst Systems

Within the National Park System lie some of this nation's most amazing caves. Grand caverns and solution formations usually come to mind when caves are mentioned. Pinnacles, though, has a much different type of caves in structure and formation. The talus caves of the Monument were formed when steep, narrow canyons filled with a jumbled mass of boulders from the cliffs above. The canyons are the result of faults and fractures in the central area of volcanic rock. These shear fractures filled with gigantic toppled boulders are clear windows into the geologic wonder of the Monument.

Pinnacles National Monument has two main areas of caves; the Bear Gulch Caves are near headquarters in the East District, and the Balconies Caves are near Chaparral Campground in the West District. A few poorly documented areas of small talus caves are scattered around. The rockfall that filled the fractures is thought to have occurred during the last series of ice ages. Despite the age of this formation, the process of rockfall and weathering continues. The boulders range from a few ounces to thousands of tons. Much of the rock matrix is supported by gravel and sand that has become lodged between the boulders, or has formed at the contact points of the stones over the centuries. These smaller particles are particularly susceptible to erosion during the flash floods that occasionally rush through the caves.

There is no known evidence of Native American habitation in any caves, though extensive archeological work is yet to be done, and local Native (Mutsun and Chalone) stories have largely died with their tellers. Non-Indian legends that have survived refer to the use of the caves as a hideout by the notorious central California bandito Tiburcio Vasquez, whose brutal contribution to local history ended with his hanging in San Jose, California, in 1875. Stories of hidden treasure and robber's roosts still cycle through campfire stories and local lore, but the location of Tiburcio's hides seem speculative.

The Civilian Conservation Corps built trails through the caves in the 1930's and these trails have endured many storms and travelers. The stairways and bridges they constructed were needed to navigate the caves without the use of ropes and ladders. Today, the Bear Gulch and Balconies caves are principle attractions for visitors at the Monument.

Geologic Formations

The faults within the Monument mark distinct boundaries in geology. The Pinnacles Fault juxtaposes granitic basement rock west of the fault and the Pinnacles Volcanic Formation east of the fault. The Chalone Creek fault juxtaposes the Pinnacles Volcanic Formation west of the fault and the Temblor Fanglomerates east of the fault.

The granitic basement is the Santa Lucia Granite and Granodiorite. These granites formed when masses of molten lava slowly cooled as they rose through the earth’s crust to a point where they completely solidified. A slow cooling process allows individual crystals to grow fairly large. Subsequent uplift from faulting and erosion of overlying material exposed these rocks at the earth’s surface. These are the oldest rocks in the park, 78-100 million years old. They form the basement upon which the rest of the rocks at the Monument lie.

The Pinnacles Volcanic Formation formed approximately 23 million years ago as it was extruded and deposited atop the granitic basement. The magma that was the source of all the volcanics was rhyolitic in origin. The formation consists of rocks such as banded and massive rhyolite, some andesites and dacites and various pyroclastic units.

The High Peaks consists of a relatively strong, well-consolidated breccia. The layers of breccias are thought to have formed as the result of material slumping off the sides of the volcano near the vents causing large landslides. The volcano was likely near water and the landslides traveled as massive turbidity currents under water that spread the material considerable distances until coming to rest near distant edges of the volcano. Volcanic ash and rhyolitic lava flows are interlayered with these breccias. Subsequent burial and compaction hardened these layers into the consolidated rock we see today. Recent faulting, fracturing and erosion have sculpted these rock layers into vertical cliffs and spires sometimes several hundred feet high.

The Temblor Formation east of the Chalone Creek Fault is a fanglomerate unit (conglomerates deposited in an alluvial fan setting) composed of granitic and to a lesser extent volcanic detritus shed from the Santa Lucia granitic basement and the Pinnacles Volcanics.