Concord Naval Weapons Station Wildlife Tour Report

Mount Diablo Creek Watershed Planning Group

August 20, 2005

Jessica Hamburger, Watershed Coordinator

You don't have to go to Alaska or Montana to see elk locking horns during rutting season. The high-pitched bugling of the bull tule elk and their ritualistic fights to attract the cow harem are going on right in our backyards, and participants in the tour of the Concord Naval Weapons Station were lucky enough to experience them.

"I called ahead," joked our tour leader, local wildlife biologist and archeologist Jim Hale of the Contra Costa Fish and Wildlife Committee, as attendees expressed amazement at the good timing. Jim also "arranged" for us to see a golden eagle circling overhead and to hear the call of a red-shouldered hawk. Along the way, the group got an overview of the cultural and natural history of the area and learned about several threatened and endangered species that live on the base.

Stop 1. Kinne Boulevard, just past the highway overpass: Birds on the Base

Kinne Boulevard runs through one of the largest undeveloped alluvial floodplains in Contra Costa County. Mount Diablo Creek flows through the area, but it is dry at this time of year. In many places, the creek is just a drainage ditch with no natural curves or riparian vegetation.

Jim pointed out the highway overpass where white-throated swifts and cliff swallows build their nests. He said that the base has a high density of loggerhead shrikes, a species of concern. (See Appendix for more on the loggerhead shrike.)

Stop 2. Kinne Boulevard, further down the road: Elk Battles

We stopped to listen to the tule elk bugling and watch them lock horns. Jim noted that, unlike bighorn sheep, the elk do not actually hurt each other when they fight. They just push each other around until the dominant bull is standing on the highest peak. They drop their antlers after rutting (mating) and grow them back in the spring.

"What will happen to the elk when the base closes?" one of the participants asked. Jim thinks that the herd will probably stay on the base, but if not enough space is preserved for them, they will be dispersed to other locations. He noted that elk are the most dangerous (non-human) animals in the United States, in terms of the number of people killed by them each year. (See Appendix for more on the history and management of the tule elk herd on the base.)

Stop 3. Hillside overlook: Cultural and Natural History

While overlooking the creek and surrounding munitions bunkers, the group learned a little about the natural and cultural history of the area. Contra Costa County is on the edge of two Native American cultural patterns. The valley culture and the Bay Area culture were initially separate, and then they began to commingle. (See Appendix for more on the cultural history of the base.)

Jim told us that Contra Costa County once had the highest density of Native Americans in North America, about 15 people per square mile. Carbon dating of artifacts provides evidence that Native Americans had lived here for at least 10,000 years and possibly 25,000 years.

Native American lived primarily on seeds and large game, then switched to acorns and seeds. They used prescribed burns to encourage the growth of plants like the globe lily on Mount Diablo, which has edible roots. Stone mortars and pestles were used to grind acorns and some sites contain hundreds of them. The Spanish missions decimated native cultures by bringing disease, forcing native people to work in the missions, and hunting and killing those who resisted. Native cultures were wiped out in less than 30 years, by 1806. At some sites, you can see pestles still resting in the mortars, left there when the Native American were forced to flee.

"We will find more and more sites as we develop," Jim said, and many of the sites are located by creeks. For example, in Tice Creek, in the Walnut Creek Watershed, a recent excavation to build a flood management basin resulted in the unearthing of a Native American burial ground.

Historical maps show that Mount Diablo Creek once passed through a willow thicket known as "Monte del Diablo" and emptied into Galindo Creek, a tributary of Walnut Creek. That "monte", or thicket, was the site of a Chupcan village. It was probably located close to Port Chicago Highway, along the BART tracks, near Maltby Mound.

Eagles and Lions, Bears and Boars

Jim's talk was interrupted by the sighting of a golden eagle, identified as a juvenile by his white markings. One of the highest reported nesting densities of golden eagles in the world is found in the Mount Diablo Range.[1] Jim believes that the Mount Diablo Range also has the highest density of mountain lions in California, with perhaps 20 individuals living in Contra Costa County.

The area once had a very high density of grizzly bears, but they were hunted to extinction. Wild boar, which evolved when European wild boar hybridized with feral pigs, is now the top game animal.

Mount Diablo, along with Mount Tamalpais to the west and Mount Hamilton to the south, hosts isolated populations of sagebrush lizards and other species that have been wiped out at lower elevations. Because the Mount Diablo area is located at the overlap of two major ecological zones, Gilbert's skink, black sage, and many other species are the northernmost of southernmost edge of their range.

The land that is now the weapons station was probably originally an oak savanna, with perennial bunch grasses interspersed with valley oak and some blue oak. Now the base is covered with annual grasses, such as wild oats, that were brought over from Europe. The invasive plant yellow star thistle is also widespread. (See Appendix for more on grasslands on the base.) The Navy has worked in the past to revegetate some riparian areas and has done some prescribed burns.

Endangered burrowing owls live in the floodplain on the base. They use burrows excavated by ground squirrels. Any future development on the base will have to go through environmental review to ensure that the owls and other threatened and endangered species, such as loggerhead shrike, California tiger salamander, red-legged frog, and western pond turtle, are protected. (See Appendix for more on these species.)

Stop 4. Pocket valley: Red-tailed Hawk Nest

Our next stop was one of several pocket valleys with ephemeral creeks that are tributaries to Mount Diablo Creek. These valleys are some of the richest places on the base with respect to wildlife because they are protected. Jim pointed out the nest of a red-tailed hawk, and we saw a red-tail perched in a nearby tree. The valley also has a small grove of Coulter pine, planted as an experiment in reintroducing this native species. (See Appendix for more on experimental plantations.)

Stop 5. Cistern Pond

A spot of green nestled in the otherwise golden hills, Cistern Pond in summer is less of a pond than a wetland, filled with cattails and tules. The pond is home to large populations of endangered California tiger salamander and red-legged frogs.

Cistern Pond was once a Native American site and was first inhabited by white people in the late 1800s. Above the pond is an old pump house that supplied fresh water to the Bollman dairy, which operated in the 1930s in what is now the bunker area, according to John Keibel.

As we surveyed the site, we heard the high-pitched call of a red-shouldered hawk. Jim told us that this species was almost wiped out in the 1920s, but it learned to adapt to life in urban areas and can now be found all over, with 85 percent of its nests found in eucalyptus, an introduced species.

Further down the road we saw a huge golden eagle nest. The eagles feed primarily on ground squirrels, a pest species in the surrounding urban areas. Jim noted that the use of anticoagulants to control ground squirrels can lead to secondary poisoning of the hawks and owls that eat them. This type of poisoning is most serious for smaller predators, like burrowing owls, because it results in a relatively high dose compared to their body size.

Alternative approaches to controlling ground squirrels include encouraging predation by building perches for raptors and excluding squirrels by digging trenches around yards and placing metal barriers in the trenches. These methods are described in "Living with Wildlife", a 12-page booklet produced by the Contra Costa Fish and Wildlife Committee and available from Kae Ono at (925) 335-1230 or kono@cd.co.contra-costa.ca.us. Copies will also be available at the next Planning Group meeting.

Stop 6. Near Willow Pass Road: King of the Hill

At our final stop, two more bull tule elk faced off while others watched from the far side of the hill, their antlers poking up like antennae above the ridgeline. The bulls down below found themselves on opposite sides of circular fence put in to protect a small tree. After crashing into it a couple times, one bull hooked his antlers in the fence and tossed it off to the side. Seemingly exhausted by the effort, the bulls then headed down into the creek for a drink.

"The bull on the highest peak is the dominant one and he will get to pass on his genes to the next generation," Jim told us. "But the guy with the ladies is the smart one," someone suggested, pointing to the bull standing with the harem of cows in the valley. Suddenly, the cows started to hoof it away from that bull. They were last seen headed upslope.

Appendix. Selected Excerpts from the Navy’s Integrated Natural Resources Management Plan (INRMP)

Unique Fish and Wildlife Resources

Tule Elk

Tule elk range throughout the Inland Area of Detachment Concord, their range encompassing the areas between Highway 4 to the north and Bailey Road to the south. Although tule elk are native to California, habitat loss due to agriculture as well as hunting pressure reduced their population to about 500 animals by 1970. The Tule Elk Preservation Act (PL 94-389) was approved in August of 1976 and directed a federal/state cooperative program for preservation and enhancement of tule elk in California.

In October 1976, the Navy offered the use of selected lands at Detachment Concord to CDFG as a tule elk preserve, whereafter in January 1977, seven tule elk were captured at the Tupman Tule Elk Preserve and relocated to Detachment Concord (DoN 1982b). In the proceeding years CDFG and Detachment Concord, through a cooperative management agreement…, have worked to maintain the tule elk herd at approximately 40 to 60 animals, relocating surplus animals on an as needed basis.

As of November 1999, the elk herd numbered approximately 40 to 45 and included approximately 13 females, 2 calves, and approximately 25 yearlings and adult bulls (CDFG 2000). See Section 4.3.2 for further information on Detachment Concord’s tule elk management program. In 2000, the elk herd was composed of 19 mature bulls, 5 young bulls, 16 yearlings and cows, and 4 calves, for a total of 44 elk. The National Park Service relocated three elk from Detachment Concord to the Point Reyes National Seashore. Mortality rates since 1999 have been one elk annually.

Bald and Golden Eagles

Bald eagles (Haliaeetus leucocephalus) are known to pass through Detachment Concord between nesting and wintering grounds, but there is no suitable habitat for bald eagle nesting. Golden eagles (Aquila chrysaetos) nest periodically at Detachment Concord, along the ridge tops in the inland area.

Species Potentially Present at Detachment Concord

Approximately 20 species have been identified as requiring management consideration by the coordinating agencies. …Status and presence information were gathered from the [US Fish and Wildlife Service], a search of the [California Natural Diversity Data Base], and surveys conducted by the University of Arizona.

[Selected Inland Area Species]

Burrowing owl (Athene cunicularia). A California special concern species, the burrowing owl is a yearlong resident of open, dry grassland, and desert habitats. They prefer low-growing vegetation and presence of existing ground-squirrel burrows. These two characteristics occur in several Inland Area locations of Detachment Concord (DoN 1999d). In 1993, Morrison (DoN 1999d) noted nine burrowing owl sites at six locations. The burrowing owl has long, almost bare, legs and a stubby tail. It is a plump small owl, similar in size to the American robin, with a total length of about ten inches (24 cm). Female burrowing owls are slightly smaller than males, but the sexes have similar coloring, although males often appear faded. Adults are a rich sandy-brown, thickly spotted with whites and buffs on the underparts, which are whitish and barred with brown. They have a rounded head without ear tufts, yellow eyes, white eyebrows, and a white throat with a dark brown half collar. Juveniles have buffy underparts without bars during the first few weeks after emergence from the burrow.

California tiger salamander (Ambystoma californiense). This federally designated candidate species and California special concern species resides in the Inland Area of Detachment Concord. The salamanders use four primary breeding ponds in the Inland Area: two cattle ponds in the upper hills above the spring and two ponds in the lower area, one along T Street and one across Bailey Road in the 5AT Magazine Area. Ivette Loredo, a USFWS biologist with the San Francisco Bay National Wildlife Refuge Complex wrote her masters thesis, Reproductive Ecology, Microhabitat Use, and Migration Behavior of the California Tiger Salamander, 1990 based on two studies at Detachment Concord. This document is available at the Detachment Concord ESO and abstracts for the two studies are included in Appendix F. In 1993, Morrison (DoN 1999d) noted four California tiger salamander breeding areas. A large terrestrial salamander with several white or pale yellow spots or bars on a jet-black field. Its undersurfaces are highly variable in pattern, ranging from nearly uniform white or pale yellow to variegated white or pale yellow and black. They are relatively small and have protruding eyes with black irises.

California red-legged frog (Rana aurora draytoni). Habitat associations for this federally listed threatened species include lowlands and foothills, in or near permanent sources of deep water with dense shrubby or emergent riparian vegetation (CNDDB 2000). The California red-legged frog is found at Cistern Pond and other freshwater ponds within the Inland Area. It was introduced in a cooperative effort between the Navy and the USFWS in the early 1980s. While the California red-legged frog inhabits areas of permanent freshwater, it may travel several hundred meters (over a thousand feet) to seek shelter if none is available near the water source. A moderate-sized brown, reddish brown to greenish gray frog with marked folds on the back and sides and a back pattern of small, irregular dark brown to black spots or small dark spots with light centers. It has a distinct but irregular pattern of contrasting light and dark markings in the groin, with some red coloration, variable in intensity and extent, on undersurfaces.

Loggerhead shrike (Lanius ludovicianus). A federally designated species of special concern and a California special concern species, the loggerhead shrike is a common resident and winter visitor in lowlands and foothills throughout California. Habitat needs include open areas with scattered shrubs, trees, posts, fences, utility lines, or other perches. Sometimes the species uses edges of denser habitats (Zeiner et al., 1990b). It has been confirmed observed in the grasslands at Detachment Concord during a 1999 survey (DoN 1999d). This bird is about nine inches (23 cm) long, with a gray top and back of the head. It has white underparts, a black mask, wings, and tail. There is also a white patch on the wings and white on the edges of the outer tail feathers. The bill is small and black, with a hook at the end of the upper mandible.

Northwestern pond turtle (Clemmys marmorata marmorata). This federally designated species of special concern and California special concern species is associated with permanent or nearly permanent water in a wide variety of habitats. It requires rocks, logs, or exposed soil for basking sites and may nest up to 0.3-mile (0.5-km) away from water (CNDDB 2000). A moderate-sized, drab brown or khaki-colored turtle, lacking prominent markings on its carapace. Males frequently develop a light unmottled throat and lower facial area as they become sexually mature, markings that become even more prominent with increasing age; females typically retain the mottled or darker-colored throat and facial area that juveniles possess into adulthood.

[Selected] Inland Area Vegetation Communities

Grasslands

Valley and foothill grassland occupies approximately 4,815 acres (1,949 ha) of the Inland Area at Detachment Concord. Dominant species of vegetation are primarily nonnative grass species, such as wild oat (Avena fatua), ripgut grass (Bromus diandrus), Mediterranean barley (Hordeum marinum), and Italian rye grass (Lolium multiflorum). In addition, a nonnative forb species, yellow star thistle (Centaurea solstitialis), has become established on many of the disturbed grassland areas, with large concentrations near the Old Airport and Magazine areas.

The nonnative annual grasses were introduced to California during the 1700s and 1800s. The most extensive and least disturbed areas of grassland occur on steep slopes and high ridges of both the Tidal and Inland Areas. In the lowland portion of Detachment Concord, large areas are occupied by magazines and other storage and transport facilities. These operations and support facilities are dispersed for safety and are surrounded by grassland vegetation similar to that found in the surrounding foothills.

Anthropogenic Areas

Approximately 161 acres (65 ha) of the Inland Area of Detachment Concord are occupied by habitat types resulting from historical activities. Several of these have survived from early homesteads established before Detachment Concord was established. A common feature among anthropogenic vegetation communities is exotic species composition and low-to-moderate tree heights.

Remnant orchards, homestead plantings of exotic shade trees, street and garden trees on the former Port Chicago townsite, and established forestry plantations are grouped in this habitat type. Several forestry plantations, composed of test plantings of various pine and eucalyptus species, are along the southern boundary of Detachment Concord, just west of Bailey Road. Approximately 90 acres (36 ha) have been planted by the US Forest Service Institute of Forest Genetics as experimental plantings.

Groves of large blue gum eucalyptus trees (Eucalyptus globulus) occur at nine locations at Detachment Concord. These groves apparently were planted by homesteaders as windbreaks and shade trees during the late 1800s. Many of the trees are now over 100 feet (30 meters) tall and provide a unique type of habitat. Understory vegetation is composed of herbaceous species characteristic of surrounding grasslands. The eucalyptus groves are considered separate from orchards and homesteads because they consist of mature trees and are structurally different from those found in orchards and plantations, due to their height and age.

An abandoned rock quarry is near the Cistern Pond at the foot of the eastern hills of Detachment Concord’s Inland Area. The three-acre (one-ha) site provides a complex of boulders and rock crevices not found elsewhere at Detachment Concord. Vegetation consists primarily of herbaceous species characteristic of surrounding grassland, with a few scattered shrubs.

There are stock ponds, watering holes, and other seepage ponds at nearly 20 locations throughout Detachment Concord. Many of these areas support aquatic vegetation.

Valley Oak Woodland

Valley oak woodland habitat occurs at several locations within the Inland Area of Detachment Concord, occupying approximately 60 acres (24 ha). Open woodlands of valley oaks occur within the southeast near Bailey Road. Valley oaks also are scattered across several low hills, both north and south of Bailey Road. In several steep canyons at the far eastern corner of Detachment Concord, there are dense woodlands of valley oaks and California buckeyes (Aesculus californica). On both the low hill sites and the steep canyon sites, understory vegetation is typically limited to grasses and forbs characteristic of surrounding grassland habitats. Scattered shrubs, such as coyote bush (Baccharis pilularis) and poison oak (Toxicidendron diversilobum) also may occur within this habitat.

Cultural History and Diversity

Until recently, nothing was known about cultures living in Contra Costa County prior to about 4,000 years ago as no sites predating this time had ever been identified. This changed when work conducted at Los Vaqueros resulted in the discovery of archaeological components dating back as much as 9,000 years. … Several areas at Detachment Concord could contain deeply buried material predating 4,000 years old (DoN 2000a).

…Detachment Concord falls between two reasonably well-documented cultural areas, one in the San Francisco Bay Area (Berkeley Pattern) and the other in the Sacramento-San Joaquin Delta (Windmiller Pattern). These separate cultures coexisted as early as 5,000 years ago, but the nature of their relationship and extent of territorial distributions have never been fully explored or defined.

It appears that by 2,000 years ago, Meganos people from the Central Valley moved into the Bay Area through Contra Costa County. It has been inferred that the Meganos culture should have controlled the lands of Detachment Concord between 1,900 and 1,300 years ago. Very few sites attributed to the Meganos Culture have been investigated or fully reported using modern methods; consequently, little is known about the impetus and nature of this cultural replacement (DoN 2000a).

3.12.4 Summary of Known Resources in the Inland Area

One prehistoric archaeological site (CA-CCo-680) and one historical corral/holding pen (P-07-000-485) have been recorded in the Inland Area. CA-CCo-680 consists of a sparse yet diverse deposit of Native American artifacts (e.g., mortars and pestles, an antler wedge, a stone “chopper,” and other flaked stone tools and debris) and dietary remains (e.g., mammal bone and marine and freshwater shellfish). A possible hearth feature and several pieces of human bone also were identified as the result of a small test excavation (DoN 2000a). A preliminary assessment concluded that CA-Cco-680 may qualify for listing on the NRHP, although the site was not formally evaluated (DoN 2000a). A prehistoric isolate also has been located at Detachment Concord. The site consists of a single, lanceolate, obsidian biface (stone tool) found near a spring in the northeastern Inland Area.

Port Chicago Navy Magazine National Memorial

In 1992, Congress established the Port Chicago Navy Magazine National Memorial to commemorate the most severe stateside disaster of World War II. An explosion on July 17, 1944, destroyed two ships and a loading pier, killing 320 people and injuring 390 people. Among the dead were both military personnel and Port Chicago civilians. The blast occurred while the S.S.E.A. Bryan and the S.S. Quinault Victory were in the process of being loaded. The force of the explosion damaged the Port Chicago Navy Magazine and many of the homes and buildings in the area and broke glass in buildings as far away as San Francisco (DoN 1994a). In coordination with the National Park Service, a permanent memorial was erected in 1994, the 50th anniversary of the disaster. The memorial, located near the explosion site, replaced a more simple design installed several years earlier in the Tidal Area, near the site of the explosion. Due to safety concerns, the memorial is not open to the public on a daily basis. On the anniversary of the explosion, the memorial is open to the public in honor of those who were killed or injured.

Reference

Integrated Natural Resources Management Plan and Environmental Assessment, Naval Weapons Station Seal Beach, Detachment Concord, California, March 2002. http://www.sbeach.navy.mil/Programs/environmental/IR/Reading_Room/Read_CO/Misc/CO_INRMP_2002-03.pdf

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[1] Hunt, W.G., R.E. Jackman, T.L. Hunt, D.E. Driscoll and L. Culp. 1998. A population study of Golden Eagles in the Altamont Pass Wind Resource Area: population trend analysis 1994-1997. NREL/SR-500-26092. Rep. from Predatory Bird Res. Group, Univ. Calif., Santa Cruz, CA, for Nat. Renewable Energy Lab., Golden, CO. 33 p. Available from Nat. Tech. Inform. Serv., Springfield, VA. http://www.nrel.gov/docs/fy99osti/26092.pdf