The Naval Air Station Point Mugu, California, (NASPM) provides habitat for six federal or state listed endangered or threatened species of birds and plants. Military activities on station combined with civilian activities around the station have negatively impacted the habitat of these species for at least the last 75 years. In an effort to help reduce the impact to endangered species habitat of military activities on base, assist the military in planning of military activities and infrastructure maintenance, and assist in the recovery of these species, a GIS coverage depicting the level of ecological sensitivity of all areas on the base was developed.

The use of geographic information systems (GIS) in government, industry, and education has become increasingly common since the early 1980's. Many public and private agencies responsible for the management of natural resources including park and forestlands, wilderness and wildlife preserves, recreational areas, rangeland, and watersheds incorporate GIS into management planning. At NASPM, the development of GIS as a tool for natural resources management began in the early 1990’s. Since then the database has grown to include nearly 300 coverages containing data not only for the base at Point Mugu itself, but also for the associated offshore landing field on San Nicolas Island, and the sea range which lies between. The purpose of this data set is to assist natural resource managers on both the mainland and San Nicolas Island with day to day management of endangered species, and the preservation of natural areas. A part of this mission is providing ecological data to the military planners, thereby allowing them to plan military activities so as to have the least amount of impact on these resources.

The objective in creating the ecologically sensitive areas coverage for NASPM was to provide the Natural Resource Management Office (NRMO) with a quick and consistent estimation of the level of ecological sensitivity in any given area on base. In addition, it was hoped that this coverage could be provided to military and civilian planners as a reference to be used in the early stages of mission operations and construction planning, giving them an easy visual reminder of which areas on station would require regulatory compliance with other federal and state agencies before infrastructure work or military operations could be carried out.

NASPM is located approximately 50 miles northwest of Los Angeles, situated on the coast adjacent to the Santa Monica Mountains National Park. Two shallow arms of the Pacific Ocean extend inland creating the Mugu Lagoon, into which drains Calleguas Creek. Calleguas Creek watershed drains the Simi Valley and the Oxnard Plain; much of this area is now either urban or agricultural in nature.

The first report by Europeans of the Point Mugu area was in 1542, when Juan Rodriguez Cabrillo landed there. Historical records as well as archaeological information indicate that the Mugu lagoon area was the site of at least three Ventureno Chumash villages. These villages represented a major center of Chumash culture until the late 1700’s, when all inhabitants were moved to the Mission San Buenaventura. It was at this time that the Spanish government was establishing a series of missions along the coast, beginning in San Diego. To feed the people they had relocated in Ventura County, the Spanish introduced the cultivation of wheat, as well as cattle ranching. It is believed that during the late 1700’s and early 1800’s, the marsh area in close proximity to the Mugu lagoon was unexploited; cattle ranching may have taken place on the grasslands bordering the marsh.

In 1822, after Mexico obtained independence from Spain, California became a part of Mexico. The Spanish mission system was dismantled, and the land divided into ‘ranchos’. The area that is now NASPM was held as part of two different ranchos. For the next 20 years, the holders of this land did relatively little with it – a possible exception would be cattle ranching. By 1870, the Mexican-American War had ended the Mexican rule of California, and the area had come under the control of the United States. An influx of American settlers ensued. A two-year drought in the early 1860’s decimated cattle ranches and led to the popularity of sheep ranching. The first official map of the Mugu Lagoon area was published in 1857 by the U.S. Coast Survey.

By the 1870’s the area north of Pt. Mugu, on the Oxnard Plain, was becoming heavily used for agriculture. Major crops included barley and corn; sheep and pigs were also raised in the area. The 1901 arrival of the Southern Pacific railroad in the area further contributed to the development of local agriculture. Lima beans became a staple and primary crop for the Oxnard Plain area will into the 20^th century. The town of Oxnard was incorporated in 1903; it had grown up around a sugar beet factory and associated railroad spur, which were opened in the late 1890’s. Throughout WWI and the 1920’s, the sugar beet factory attracted foreign workers, settlement, and development to the Oxnard Plain area. Up until the 1920’s however, the Mugu Lagoon itself had managed to remain largely void of settlement. According to the USGS quad of the area dated 1901, there were no more than four structures within the Mugu Lagoon area.

As early as 1884, portions of Calleguas Creek, which drains directly into the Mugu Lagoon from the Oxnard Plain, were channelized to accommodate farmers, who wanted to limit damage from the creek’s floodwaters. As such, the area around the lagoon became a sump for the agricultural lands above. In the 1920’s the Pacific Coast Highway (California State Highway 1) was extended north far enough for hunting and fishing enthusiasts to reach the Mugu Lagoon. An abundance of hunting clubs and fish camps immediately sprang up in the area. The Ventura County Game Preserve was developed to the northwest of Pt. Mugu in 1908. The main purpose of waterfowl hunting was supplemented by limited agriculture in the area; the produce was used to feed the ducks. Buildings and levees for ponding were build on the land by the Preserve.

In the 1920’s agricultural drainage into the lagoon increased with the channelization of the lower reaches of Calleguas Creek as well as the creation of the Oxnard Drainage District, District 2, and District 3. These districts served the agricultural areas around the Mugu Lagoon, and emptied either directly or indirectly into the lagoon. The next detailed mapping of the area by the U.S. Coast and Geodetic Survey was done in 1932. At this time, the area immediately north of the west arm of the lagoon was under cultivation. By the time of the 1947 mapping, it was noted that lima beans had been grown along the northern margin of the lagoon for 20 to 30 years previously

Also appearing on the 1932 map were the structures associated with the Mugu Fish Camp. This facility was located on the sand spit between the lagoon and the Pacific Ocean, and included a bridge across the lagoon and roadway through the marsh connecting to the Pacific Coast Highway. One note indicated that the small bridge had effectively closed off the western half of the lagoon. By the mid-1930’s a very small Japanese fishing community was also located near the bridge. Other structures associated with the village included a pier, boardwalk, concrete bait tanks, parking areas, and many small structures. In 1938 Hollywood came to the lagoon with the shooting of The Real Glory starring Gary Cooper.

In 1939 a major storm destroyed much of the fish camp, including the pier. The demolished buildings were replaced, in many cases with larger structures, and the pier was rebuilt. In 1940, A Yank in the RAF was filmed on the site, this time in the marshlands behind the lagoon. In about 1943 the bridge over the lagoon was replaced with a higher bridge. While decades of agricultural runoff to the lagoon as well as recreation and construction on the sand spit certainly took their toll on the area, it was the arrival of the military in 1942 that signaled the most detrimental and lasting impacts on the Mugu Lagoon and surrounding marsh.

In early 1942, the open area around the lagoon became the focus for Seabee training, attracting Seabees stationed just north at Port Hueneme. In order to use the land, the Navy leased signed leases with the two major owners. Covering some 4000 acres, the station was already beginning to take on its current shape. The establishment of a formal military base was authorized in 1946, and by the early 1950’s the Navy owned all the land it was occupying. All civilian activity on the area ceased. During this decade of military occupation, many of the current main structures were built, including portions of the runway and housing structures. In addition, the mouth of Calleguas Creek was dredged and the material used as fill on the station.

"Located off the coast of Southern California, the Naval Air Warfare Center Weapons Division (NAWCWPNS) Sea Range at the Naval Air Weapons Station (NAWS) Point Mugu is the Navy's most instrumented and expansive over-water range. As a result, the Sea Range provides a safe place for conducting test, evaluation, and training activities that require a large expanse of air and sea space. The Sea Range's assets, on and off the coast of California, provide an ideal setting of geography, topography, and climate for conducting these activities efficiently and cost-effectively. In addition to the NAWS Point Mugu, assets include Laguna Peak and San Nicolas, Santa Cruz, and San Miguel islands. The Point Mugu Sea Range, is, therefore, considered a critical resource for maximizing the operational readiness of U.S. armed forces and its allies.

The range of testing and training activities currently conducted on the Sea Range can be broken down into several types, including air-to-air, air-to-surface, surface-to-air, surface-to-surface, and fleet exercises. Objects used to conduct these exercises include targets, missiles, aircraft, and ships. The Sea Range contains a multitude of biological and cultural resources and, therefore, maintains various resource management programs. These programs help protect archaeological sites, critical habitats, and wildlife, including marine mammals and marine and migratory birds.

As steward of about 25 million acres of land in the United States, the Department of Defense and its military agencies are committed to responsible environmental management. In 1989, the Secretary of Defense issued an Environmental Management Policy Statement throughout the military agencies to "be the Federal leader in agency environmental compliance and protection". The Navy is fully committed to integrating its military and environmental missions. This is accomplished by practicing sound environmental management guided by four basic principles: to comply with environmental requirements; to restore by cleanup of past operations pollutants; to prevent pollution in current and future operations; and to conserve irreplaceable natural and cultural resources. The Navy is committed to protecting and enhancing the environmental quality of the lands for which it is responsible, ensuring that the environment that we pass on to coming generations is of an even better quality than the environment we enjoy today."

Decisions by the Navy for mission operations or construction and maintenance activities are clearly regulated by a variety of federal and state laws. Under the Endangered Species Act (ESA) of 1973, as amended, the Navy as a federal agency is to use all of its authority (i.e. direction, funding, professional staff) to assist the U.S. Fish and Wildlife Service in the recovery listed species on Navy owned land. ESA grants authority to FWS and imposes requirements upon Federal agencies, such as the Navy, regarding protection of endangered and threatened species and their habitats. ESA directs Federal agencies to utilize their authorities to carry out conservation programs for listed species. Each Federal agency shall, in consultation with, and with the assistance of the Secretary, insure that any action authorized, funded or carried out by such agency is not likely to jeopardize the continued existence of any endangered or threatened species or result in the destruction or adverse modification of habitat of such species.

ESA promulgates several things:

• Ensure that Navy actions or activities, such as aircraft overflights, pest management, missile launch, are not likely to jeopardize the continued existence of any endangered or threatened species.
• Ensure that Navy actions or activities do not result in the destruction or adverse modification of critical habitat
• Requires Federal agencies to implement mitigation and compensatory measures to compensate any and all incidental "take" as defined under ESA.

Defined under ESA, take means "to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct." Harm includes significant habitat modification or degradation which actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding or sheltering. Harassment is an international or negligent action that creates the likelihood of injury to wildlife by annoying it to such an extent as to significantly disrupt normal behavior patterns which include, but are not limited to, breeding, feeding or sheltering.

Ten separate data coverages were used in the production of the environmental sensitivity map for Point Mugu. Each coverage was weighted as follows:

Coverage Weight

Light-footed Clapper Rail 512

Snowy Plover 256

Salt-marsh Bird’s Beak 128

Least Tern 64

Physiographic Habitat Categories 32

Harbor Seal 16

Brown Pelican 8

High Bird Species Diversity 4

Jurisdictional Wetlands 2

Belding’s Savannah Sparrow 1

Light-footed clapper rail. The light-footed clapper rail is a very rare, secretive resident bird, inhabiting Mugu Lagoon year round. It occupies intertidal salt marsh habitat in very restricted, localized areas. Nesting habitat for rails at Mugu Lagoon is stands of spiny rush (Juncus acutus) and high marsh Salicornia hummocks isolated from upland access by creeks, mudflats, or low marsh. Light-footed clapper rails forage along the mudflat-marsh interface, along mudbanks, and shallow tidal creeks. At times, rails will forage in the high marsh. Their diet consists of crabs (Pachygrapsus, Hemigrapsus), and salt marsh gastropods (Cerithidea).

The 1998 call count data yielded four pair with five single males for an adult population of 13 birds. The 1999 call count data indicate a breeding population of 4 pairs with 6 single males, however, one male was predated by an immature red-tailed hawk the day after the annual air show, leaving the population the same as 1998. It is unclear what factor or factors are keeping the flight-footed clapper rail population in low breeding numbers over the last decade. Low genetic variability and persistent organochloride and heavy metal contamination are possible leading indicators in the hypothesis. This is the only breeding population in Ventura County. The nearest breeding population is 80 miles southeast of NASPM

Snowy Plovers: Snowy plovers are year round residents at Mugu Lagoon. This Federally threatened species utilizes open, dune-backed sand beach habitats for breeding and foraging. Some snowy plovers do migrate. It is surmised that some breeding birds from our beach move south and are replaced by individuals from more northern latitudes. Nesting commences in mid to late March with young still on the beach until late August to early September.

Snowy plovers nest on barren to sparsely vegetated beaches, dry salt flats in lagoons, barrier breaches, an on dune backed beaches. At NASPM plovers forage on open beaches, tide flats (primarily during the winter), salt flats and salt ponds. On beaches, plovers forage above and below the mean high water line, gathering food from sand surfaces, kelp, marine mammals carcasses, or low foredune vegetation. They feed on small crabs, amphipods, and sand hoppers.

Population numbers for snowy plovers remain very low, but NASPM supports the largest breeding population in Ventura County. The nearest breeding populations outside of the county are 135 miles to the north and 130 miles to the south. Reasons for this reduced population can be linked to continued human disturbance coupled with potential increased mammal and avian predation.

Salt Marsh Bird’s-beak. Salt marsh birds-beak is established in habitat that generally forms a "bathtub ring" around the outer periphery of the salt marsh. This tends to be in high salt marsh or hummock areas. The plant has a very narrow ecology: 1) it grows on the roots of specific host plants which include Distichlis spicata, Monanthochloe littoralis, and Salicornia virginica; 2) has very specific host pollinators; 3) cannot be immersed in salt water for any long duration; 4) usually needs freshwater to germinate; 5) the seed wings are dispersed through floating to the marsh edge.

World population of this species is restricted to four populations in southern California of which Mugu Lagoon has the largest. The nearest viable population is 90 miles southeast of NASPM.

Least Tern: The California least tern is a common summer resident. Least terns utilize Mugu Lagoon and the ocean immediately offshore for foraging during their seasonal migrations and for breeding duration. Even birds from nearby Ormond Beach use the lagoon for consistent foraging forays. Least terns nesting at NASPM’s ‘Ormond Beach East’ site continue to be impacted by spring high tides and, at times, high swells from Pacific storms coupled with high tides, as well as avian and mammalian predators.

Habitat Coverages: The physiographic habitat types coverage is an important tool for habitat and species management. This is especially true when managing endangered or threatened species, wetlands, and the largest salt marsh estuary in southern California. Of the many physiographic habitat types defined and mapped for Mugu Lagoon, four are strategic: intertidal salt marsh, intertidal mudflat, non-tidal salt marsh, and salt marsh/salt panne. These habitat types are most crucial to the majority of listed species as well as the vast array of waterbird species and the tens of thousands of individual birds (waterfowl, waders, and shorebirds).

Harbor Seals: Mugu Lagoon boast the second largest haul out area for harbor seals in the Southern California Bight. These pennipeds are protected under the Marine Mammal Protection Act (MMPA) from harm and harassment. Of crucial importance are the intertidal mudflats that are used as the pupping area for these seals. Mugu Lagoon supports a population of 130-270 harbor seals with about 25-35 pups being born per year. Harbor seals will utilize the lagoon for foraging and playing when there is a high tide. The highest tides will move most of the seals out to the near shore marine environment where they often feed.

Brown Pelican. Mugu Lagoon is the most important estuarine roost site in the SCB and one of the most consistently used large roost overall. It is the closest large mainland roost to the major breeding colony and night roost at Anacapa Island, and serves as a staging area for birds moving to and from the island. The lagoon represents a relatively secure roost site due to the restricted pubic access and current Navy management policies. In contrast, many other roosts along the southern California coast were not formally protected and remain vulnerable to changes that could result in loss of essential non-breeding habitat for the brown pelican.

Waterbirds: Waterbirds as a group consist of waterfowl, waders, and shorebirds. The Mugu Lagoon at NASPM is the third largest spring migration stopover habitat for shorebirds. The density of shorebirds during this migration ranges from 60,000 to 75,000 individuals. The fall migration of shorebirds for NASPM, Mugu Lagoon, shows a significantly smaller number of shorebirds using the estuary. Nonetheless, the intertidal mudflat, tidal creeks, and intertidal salt marsh provide excellent habitat for these waterbirds as a group. Mugu Lagoon has a very active community support program in the form of ecological field tours and bird field trips/classes with a variety of organizations within 45 miles of Mugu Lagoon. Natural Resources Management also has many research efforts ongoing as well as ecological field classes from a variety of universities using Mugu Lagoon.

Wetlands: Jurisdictional wetlands comprise about 2,500 acres of the 4,500 acres at NASPM. Mugu Lagoon is the largest salt marsh estuary in southern California, and it retains many functional wetland elements and values. Socio-economic values of wetlands in the estuarine system are society's perceptions of the worth of an estuarine ecosystem, typically stemming from whether the system provides a form of benefit or pleasure (adapted from Ferren et al. 1996). Most of the values are derived from the various ecosystem functions that characterize a particular wetland or ecosystem.

The consumptive value of estuaries for regional commercial fisheries has probably been underestimated. Halibut are now considered estuarine-dependent species because of the importance of estuaries to their young-of-the-year (Onuf and Quammen 1990). Many non-consumptive values are attributed to estuaries and estuarine wetlands that generally relate to the enhancement of the quality of life for humans that live near or visit them. Educational programs, research sites, and conservation areas also are tributes to the acknowledged values of estuaries and estuarine wetlands. Various municipalities use urban estuaries as part of their parks and recreation educational programs. Universities and colleges have conservation and research programs that focus on estuaries. Furthermore, federal, state and county agencies maintain parks, reserves, and refuges to protect estuaries and their functions and values in the public trust.

Belding’s Savannah Sparrow: Belding’s savannah sparrows (BSSP) are obligate, year round common residents of the salt marsh vegetation type of Mugu Lagoon. BSSP’s initiate their breeding cycle in late December or early January when males begin to defend territories. At times, it could be weather dependent. Nest building begins in mid-to-late March with eggs laid in early April. The first broods hatch in mid-April, and the young fledge within ten days. Females renest and may raise as many as three broods in a season. The nesting season is completed by mid-August.

Breeding territories are found predominantly in the upper salt marsh, where pickleweed (Salicornia virginica) dominates the vegetation. The size of an individual territory can be quite small, thus BSSP’s may occur in a relatively high density. Nests are built on the ground or in the low branches of salt marsh plants and are usually placed above the reach of tidal flooding. High spring tides may wet the vegetation supporting the nest, but inundation occurs only with storm tides. Foraging occurs throughout the salt marsh and adjacent area, including some beaches.

Male BSSP defend their territories throughout the breeding season, although territorial behavior is most intense earlier in the season. Territorial defense is exhibited through singing (only males use the primary song), prominent perching within the territory boundaries, surveying, and chasing other BSSP. The peak of territorial activity occurs in the first several hours after sunrise. Once females begin to nest there is a reduction in male song, although males continue to defend territories. Female BSSP in contrast, tend to be secretive in their behavior and relatively inconspicuous throughout the breeding season.

Four statewide censuses of breeding BSSP have been conducted in California. Barbara Massey censused all potential sites in 1977 and estimated 250 territorial males. A complete census in 1986 (males by Richard Zembal and colleagues) resulted in an estimate of 446 territorial males. The last statewide census in 1991 resulted in a minimum of 239 territorial males. Mugu Lagoon has consistently supported one of the largest populations in the state with estimates of breeding pairs increasing overall from 1973 to 1991. It is important to understand that the number of territorial males is closely correlated to the estimated number of pairs but it is not actually the number of pairs.

A total of 935 territorial male BSSP's were counted during the first, complete census in late March-early April 1993. The total of 935 territorial males at Mugu Lagoon is the highest count of any published census. A comparison of the population estimates of BSSP at Mugu Lagoon over the past 20 years show gradually increasing numbers. This increase may be due, in whole or in part, to differences in census technique and the extent of census coverage, both in terms of physical area covered and in total observer hours spent. The 48 observer hours spent in 1993 is more than twice the time spent during the previous surveys, and survey techniques have not been uniform over the years.

In addition to the species coverages outlined above, all physiographic habitats on station which were coded as ‘urbanized’ were weighted –2. The order of weighting was determined by the station ecologist/natural resources manager. The rationale for the weights themselves is based on the ability to add together a series of weights and still be able to identify if the sum is determined by only one individual coverage weight, or a series of weights. For example, a combined weight of 16 can only mean that the only factor that needs to be considered at that spot is harbor seals. This is true because even the sum of all lower weights (8,4,2,1) will only equal 15. There were specific reasons and priorities given for weighting the natural resources for the sensitivity designations. A synopsis of the current condition and/or habitat requirements of the species represented is listed below.

Once all contributing coverages were coded with the appropriate weights, the construction of the final coverage was a simple matter of using the ‘union’ command to join the coverages together in steps. This analysis was done with vector data rather than raster data to retain the very fine articulation of some of the coverage boundaries. The final coverage was clipped to a predefined boundary that consisted of the station boundary to the north and the extent of the least tern offshore foraging areas to the south (ocean side). This left some small slivers on beach areas, which fell between the least tern offshore foraging areas and the onshore snowy plover or other dune species coverages. These slivers were coded 64 to correspond with the least tern coverage that they bordered. All remaining polygons with a weight of 0 were recoded to –1 to keep them from being dissolved into the background polygon.

The ‘dissolve’ command was applied to this coverage using the weights as the selected item. This coverage was then reclassed into six categories based on the weights, as follows:

Category Weights

Very High 512 +

High 128-511

Moderate 64-127

Low 18-63

Very Low 1-17

Developed <0

As with the original weights themselves, these categories were determined by the base ecologist. The categorized coverage was then ‘dissolved’ again, this time using the category code. Finally, the resulting coverage was ‘eliminated’ using an area less than one acre (43,560 feet sq.) to delete very small polygons. Again, the one-acre value was selected by the base ecologist. Any sliver polygons remaining along the borders of the coverage were manually merged into the bordering polygon with the closest weight value.

The history of land use on the area now represented by NASPM indicates that the habitat for all species now using the area has been disturbed for nearly a century. Historical data are important to this analysis since they give insight into how the condition of the land has changed over time. This, in turn, may provide enough information to estimate what ecological habitat types were represented here before disturbance by man. The sensitive or endangered species that currently inhabit this area all have specific habitat requirements. Knowing these habitat requirements is very important in determining which areas on base are most in need of protection, and therefore should be rated as highly sensitive.

This analysis has been done three times to date. With each iteration, areas on base, which are classified inappropriate according to the knowledge of the base ecologist, are identified, and the process is then refined. In addition, several of the contributing coverages have changed since the first iteration. It is anticipated that this coverage may be considered temporally dependent, rather than every being really static. Occupied habitats change, wetlands are destroyed and mitigation creates new wetland areas, and bird species density changes with the season. In the future it is hoped that this coverage will be refined to the point that it is easily used by both civilian and military personnel who wish to conduct operations in this very sensitive area.

I would like to thank my co-author, Mr. Thomas Keeney, whose hard work and diligence in protecting these resources has provided most of the data for this project.

Ferren, Jr., Wayne R., P.L. Fiedler, and R.A. Leidy. 1996. Wetlands of the Central and Southern California Coast and Coastal Watersheds: A Methodology for their classification and description. U.S. Environmental Protection Agency, Region IX, San Francisco, California.

Onuf, C.P. and M.L. Quammen. 1990. Coastal and riparian wetlands of the Pacific Region: the state of knowledge about food chain support. In A Pacific Coast Regional Perspective. Pacific Regional Wetland Functions. Proceedings of a Workshop, Mill Valley, Ca. April 14-16, 1985: 95-134

Swanson, Mark T., 1994. "From Spanish Land Grants to World War II: An Overview of Historic Resources at the Naval Air Weapons Station, Point Mugu, California". Statistical Research Technical Series #50, Tucson, Arizona.