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Biotic Dimension Terrestrial VegetationAlthough comprehensive studies have been made of the vegetation on the larger islands off California’s coast (e.g., the Santa Catalina, San Clemente, San Nicolas, and Santa Barbara Islands; Año Nuevo; the Farallons), very little is known of the terrestrial botanical character of the smaller islands and rocks in the CCNM, particularly in northern California. Many of these offshore features lack soil sufficient to support complex vegetation. However, plant species found on the islands and rocks that do support vegetation are believed to be largely representative of adjacent mainland communities that existed before human disturbance and modification began; however, many of these plants may be modified in space and size based on the specific severity of their current habitat. In addition, because the islands are remote, some level of endemism may be represented by unique, as yet undocumented taxa in these communities. To date, no comprehensive surveys of the plants on these islands and rocks have been conducted to verify these hypotheses. Intertidal VegetationMarine vegetation in the CCNM includes species that are tolerant of regular, prolonged exposure and desiccation, in the splash zone and upper intertidal zone. Crustose forms of blue-green algae (Cyanophyta) and black-colored lichens typically grow in the splash zone. In the upper intertidal areas, green algae (Chlorophyta) such as sea felt (Enteromorpha spp.) and sea lettuce (Ulva spp.) typically occur. Special-Status Vegetation SpeciesNo comprehensive inventory of vegetation has been conducted in any area of the CCNM, so it is not known whether any federally or state-listed species exist on the monument’s islands or rocks. However, surveys of the larger coastal islands not included in the CCNM have identified numerous endemic plant species, many of which are currently classified as threatened or endangered. There is potential for similar endemism to occur on the larger vegetated islets, rocks, and shoreline cliffs within the CCNM. Focused botanical studies are needed to make these determinations. Non-Native Vegetation Species & Noxious WeedsOn the larger coastal islands, such as San Clemente, San Miguel, San Nicolas, Santa Barbara, and Santa Rosa Islands, non-native plants account for 20 to 58 percent of all plant species. Introduction of these species may have occurred largely because of human activity, but some level of natural dispersal from the mainland may be partly responsible. Because no comprehensive survey of the vegetated islands and rocks within the CCNM has been conducted, the percentages of non-native plants on these features are not known. The same is true for the percentages of noxious weeds. Focused botanical surveys are needed to make these determinations. BirdsNineteen species of marine birds (i.e., seabirds and shorebirds) and predatory birds consistently use offshore rocks for breeding in California (Table 1). One of these is listed as endangered under ESA, two are listed as endangered under CESA and are fully protected species in California, seven are considered California species of special concern and one has been designated a sensitive species by the BLM. Breeding habitat requirements vary among these species; some require soil, others require crevices, and many use open areas, vegetated or not. The key characteristics of these breeding sites are suitable locations for nests and the absence of terrestrial predators. A small complement of shorebirds uses the lower elevations of CCNM rocks for feeding, primarily during migration and winter. These birds include black oystercatcher, ruddy turnstone (Arenaria interpres), black turnstone (Arenaria melanocephala), wandering tattler (Heteroscelus incanus), surfbird (Aprhiza virgata), and rock sandpiper (Calidris ptilocnemis). During high tides, flocks of these species roost above the waves. The most recent inventory of seabirds on the islands and offshore rocks of California was prepared by Sowls et al. (1980). This survey, while comprehensive, is critically in need of updating. Populations of some of the larger seabirds such as common murre have been surveyed from the air, but many small breeding populations of seabirds have not been surveyed since the 1970s (Manuwal et al. 2001). There is very little information on the status of most of the seabird colonies within the CCNM. This is especially true for the smallest colonies, as well as the nocturnal seabirds. Future surveys likely will document more nesting sites than previously recorded because new technology now enables surveyors to better detect some of the more secretive birds, such as storm petrels and small auklets, which are active mostly at night. In June, 2002, the firm Mad River Biologists in McKinleyville, California, conducted a literature search and summarization on CCNM Seabirds and Marine Mammals. That summary is located here in a combination of HTML and PDF formats. Table 1. Primary Breeding Birds and Predatory Birds of the CCNM
Marine MammalsSix marine mammal species regularly use offshore rocks for hauling out or breeding (Table 2). Two of these species, Steller’s sea lion and the sea otter, are listed as threatened under ESA. The Northern elephant seal and sea otter are fully protected species in California. Harbor seals and California sea lions are common on many of the rocks along the coast. Both species typically choose sites that are sheltered from disturbance by human activities, although, in some areas, the animals have acclimated to chronic human disturbance. Steller’s sea lions breed on a few of the remote CCNM rocks in northern California. The other species are found primarily on larger islands (fur seal and elephant seal), the mainland (elephant seal), or in the waters around the CCNM (sea otter). DFG and its cooperators conduct monthly surveys to document the presence of pinnipeds along the coast of California ( Fluharty 1996, Read and Reynolds 2001). A literature search and summarization of six key marine mammal species (five pinnipeds and the sea otter) was prepared for the CCNM and a copy of this document should accompanies this module (Fix et al. 2002). In June, 2002, the firm Mad River Biologists in McKinleyville, California, conducted a literature search and summarization on CCNM Seabirds and Marine Mammals. That summary is located here in a combination of HTML and PDF formats. Table 2. Marine Mammals of the CCNM
InvertebratesThe splash zone and upper intertidal zone above mean high tide provide habitat for a variety of marine invertebrates, including rock louse (Ligia occidentalis), periwinkles (Littorina spp.), limpets (Lottia spp.), chitons (e.g. Nuttalina spp.), barnacles (Chthalmalus spp.), and, during high water, hermit crabs (Pagurus spp.) and shore crabs (Pachygraspus spp.) (Also see Ricketts et al. 1985). In addition, on some of the larger islands with grass or shrub communities, a variety of invertebrates, such as land snails, grasshoppers, crickets, flies and bees, butterflies, and moths may be found, depending on proximity to the mainland and suitability of habitat. Both terrestrial and intertidal invertebrates provide food for foraging bird species, including American oystercatcher, ruddy turnstone, black turnstone, wandering tattler, surfbird, rock sandpiper, and gulls (Larus spp.). No comprehensive inventory of invertebrates has been conducted in the CCNM, so it not known whether any special-status invertebrates occur there. However, surveys of the larger coastal islands not included in the CCNM have identified numerous endemic invertebrates, including crickets, moths, and butterflies, that live on the coastal islands, but none are currently listed as threatened or endangered. No information is available regarding the presence of invasive invertebrates in the CCNM. Sensitive SpeciesOther SpeciesSpecies other than those discussed above (e.g., passerine birds) are likely to be found on the CCNM, particularly on larger rocks and islands. No comprehensive inventory of such species has been conducted to date, nor is information available regarding the presence of invasive species, special-status species, or species that may pose threats to other endemic or special-status species found in the monument.
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