Coronado Islands

The Coronado Islands are located within the central portion of the Southern California Bight, on the continental margin within Mexico's exclusive economic zone. The islands are exposed continental blocks, produced by the shear zone of the Pacific and North American plates. To the west, underwater cliffs border a deep channel over in depth. The largest and closest island, South Coronado, is located approximately off the Mexican mainland and south of the maritime border with the United States. The islands are under the jurisdiction of Mexico and Tijuana Municipality in the state of Baja California. • Pilón de Azúcar (Pile of Sugar or Middle Rock) is located at and covers . The island has a rocky guano-washed hill on the southern side, and a smaller ridge on the north side, separated by a amphitheater-shaped depression between them. The island is composed of barren, infertile sandstone, with little vegetation. A few succulent plants, such as Opuntia spp. and Dudleya spp. are present on the southern hill, although the soil tends to slough off the slopes. In the basin, straddling both peaks, herbaceous and woody plants occur in the more soil-rich depression. • Coronado Centro (Central Coronado or Middle Island) is located at and covers . This island forms a steep-hill with a peninsula-like structure on the northeast side, which creates a protected cove known as Moonlight Cove. This island is extensively weathered and beaten, with unstable material giving way in handful to slope-sized masses. The unstable and barren nature of this island is likely a result of the heavy use by breeding and roosting sea birds combined with unstable substrates. The only abundant plant community occurs on the southwest, windward side of the island. • Coronado Sur (South Coronado or South Island) is located at , and covers . It is long and wide. It has the only bay of the islands, called Puerto Cueva Cove, located one quarter the way down on the east side. The island has two main peaks, Middle Peak, located about one-third the way down the island with an elevation of about , and South Peak, approximately high. On the west side there is a cove known as Seal Cove. There are roughly a half dozen structures above Puerto Cueva, and two navigational lights at the northern and southern ends of the island. == History ==

Indigenous peoples and Spanish exploration The islands had been occupied by humans for over 1,000 years. As the islands lack any fresh water, permanent settlements would have not been feasible in the past. However, the islands were frequently visited by the local indigenous peoples (such as the Kumeyaay), who likely set up small and temporary encampments, possibly for retreats or other spiritual/sacred practices; ancient artifacts have been collected from both islands. North Island has artifacts that include teshoa flakes, and a midden on the saddle of the island. A small cave, dubbed Pirate's Cave, was reported to have had remains of ceramics. On South Island, numerous other middens exist. The artifacts may be from the La Jolla complex of peoples. Anthropologist J.P Harrington recorded the Luiseño word for the islands as "mexéelam". They have also been referred to as the Sentinels of San Diego Bay. Commercial ventures Starting in the 1860s, advertisements for day trips to the islands began making appearances in local newspapers. At the same time, commercial fishing ventures also started, focusing mostly on rock cod. The structure was ultimately destroyed in the high winds and waves of a storm in 1988. and foxholes were excavated on South Island during this period. In October 1944, Lieutenant Robert D. Cullinane, flying a Consolidated PB2Y-3 Coronado, BuNo 7051 of the VPB-13 patrol bombing squadron, perished along with the 12 members of his crew in a crash on South Coronado. Wreckage belonging to the aircraft is located on the western-facing slope of South Island. The Coronado Islands are under the jurisdiction of the municipality of Tijuana, Baja California, as ruled in the books of the Baja Californian Government, published on December 20, 1959. Today, the only inhabitants of the island are Mexican Navy personnel and a lighthouse keeper on South Island. As the islands are a natural protected area, access to the islands is restricted to governmental personnel and permitted scientists. Although landing on the islands is prohibited, the waters around them are still a frequent destination for divers, snorkelers and fishermen. == Ecology ==

Flora Plant communities The topography, soil, and human impact each have effects on the vegetation of the islands, creating varying characteristics on each island. However, the vegetation of the Coronado Islands is mostly dominated by maritime succulent scrub, a plant community within the sage scrub ecosystem of North America, characterized a predominance of succulent plants and a dependence on ocean fog as a consistent source of moisture. It forms a transitional zone between the Mediterranean ecosystems of the California Floristic Province and the subtropical deserts of western North America. It includes a number of species characteristic of the coastal sage scrub, but is complemented by a wide assemblage of endemic species, giving it the greatest species richness of any of the sage scrub communities. Some taxa representative of this environment include succulents such as liveforevers (Dudleya spp.), and cacti like the coastal cholla (Cylindropuntia prolifera), coastal prickly pear (Opuntia littoralis) and the golden-spined cereus (Bergerocactus emoryi). in flower, with Bergerocactus emoryi'' visible around it This habitat is most typical of northwestern Baja California, ranging from the town of San Vicente to the vicinity of Punta San Carlos, a coastal swathe of about . It occurs farther north, but in a more fragmented pattern, occupying the fringe coastal bluffs and mesas up to the Mexico–United States border and sparsely north to Torrey Pines State Natural Reserve in San Diego County, California. It is also present on the other offshore islands of the region, including Isla San Martin and Todos Santos Island, but also portions of San Clemente and Santa Catalina Island in the southern Channel Islands of California. Anacardiaceae • Rhus integrifolia Apiaceae • Apiastrum angustifolium • Daucus pusillus Asteraceae • Amblyopappus pusillus • Artemisia californica • Baccharis sarothroides • Chaenactis glabriuscula var. glabriuscula • Encelia californica • Eriophyllum confertiflorum • Hazardia berberidis • Hazardia orcuttii • Lasthenia coronaria • Lasthenia gracilis • Leptosyne maritima • Logfia filaginoides • Malacothrix foliosa • Malacothrix insularis • Malacothrix similis • Perityle emoryi • Pseudognaphalium biolettii • Pseudognaphalium microcephalum • Pseudognaphalium ramosissimum • Rafinesquia californica • Stephanomeria diegensis • Uropappus lindleyi Boraginaceae • Cryptantha intermedia • var. intermedia • var. johnstonii • Cryptantha maritima var. maritima Brassicaceae • Descurainia pinnata • var. brachycarpa • var. glabra • Lepidium oblongum var. insulare Cactaceae • Bergerocactus emoryi • Cylindropuntia prolifera • Mammillaria dioica • Opuntia littoralis • Opuntia oricola Caryophyllaceae • Silene laciniata ssp. laciniata • Spergularia macrotheca var. macrotheca Chenopodiaceae • Aphanisma blitoides • Atriplex canescens ssp. canescens • Atriplex pacifica • Atriplex serenana var. davidsonii • Chenopodium californicum • Extriplex californica • Suaeda taxifolia Cleomaceae • Peritoma arborea var. globosa Convolvulaceae • Calystegia macrostegia • ssp. cyclostegia • ssp. intermedia • Dichondra occidentalis Crassulaceae • Crassula connata • Dudleya anomala • Dudleya attenuata ssp. attenuata • Dudleya candida • Dudleya lanceolata • Dudleya × semiteres Cucurbitaceae • Marah macrocarpa var. macrocarpa Euphorbiaceae • Euphorbia misera Fabaceae • Acmispon glaber • Acmispon maritimus ssp. brevivexillus • Acmispon watsonii • Astragalus trichopodus var. lonchus • Lupinus succulentus • Lupinus truncatus • Trifolium willdenovii • Vicia hassei Hydrophyllaceae • Eucrypta chrysanthemifolia var. chrysanthemifolia • Phacelia distans • Phacelia ixodes var. plumosa • Pholistoma auritum • Pholistoma racemosum Liliaceae • Calochortus splendens Malvaceae • Malva occidentalis Montiaceae • Cistanthe maritima • Claytonia perfoliata ssp. mexicana Nyctaginaceae • Mirabilis laevis var. crassifolia Orchidaceae • Piperia cooperi Papaveraceae • Eschscholzia californica • Eschscholzia ramosa • Papaver heterophyllum Plantaginaceae • Antirrhinum nuttallianum ssp. subsessile • Collinsia heterophylla var. heterophylla • Nuttallanthus texanus Poaceae • Achnatherum diegoense • Agrostis pallens • Bromus arizonicus • Bromus carinatus • Distichlis spicata • Elymus condensatus • Elymus triticoides • Melica imperfecta • Muhlenbergia microsperma • Nassella pulchra Polemoniaceae • Gilia achilleifolia ssp. abrotanifolia • Linanthus dianthiflorus Polygonaceae • Eriogonum fasciculatum • Pterostegia drymarioides Polypodiaceae • Polypodium californicum Pteridaceae • Pellaea andromedifolia var. pubescens • Pentagramma triangularis Ranunculaceae • Clematis pauciflora • Delphinium parryi ssp. maritimum Resedaceae • Oligomeris linifolia Rhamnaceae • Rhamnus insula Rosaceae • Heteromeles arbutifolia Rubiaceae • Galium angustifolium ssp. angustifolium • Galium aparine • Galium coronadoense Sapindaceae • Aesculus parryi Saxifragaceae • Jepsonia parryi Solanaceae • Lycium californicum • Nicotiana clevelandii • Solanum americanum Themidaceae • Dichelostemma capitatum ssp. capitatum Urticaceae • Parietaria hespera var. californica Zosteraceae • Phyllospadix scouleri Fauna There are colonies of birds that nest on the islands and can be spotted in the nearby waters like gulls, cormorants, pelicans, storm-petrels, and alcids. The Coronado Islands have the largest known colony of the rare Scripps's murrelet. Pilón de Azúcar, better known as Middle Rock, is host to the northernmost nesting colony of brown boobies on the west coast of North America. Ten species of reptiles and amphibians are also found on the islands. The best known is the Coronado rattlesnake (Crotalus oreganus caliginis), which is a smaller subspecies than the one found on the mainland. There is also the Coronado Island gopher snake, which feeds off birds' eggs, the Coronado skink, which is found on all four islands, and the arboreal salamanders which live on the three biggest islands. Southern alligator lizards are found on the north, south and central islands. There are two types of land mammals on the islands: rabbits and mice. How they reached the islands is currently unknown. Sea mammals are plentiful and it is not uncommon to see groups of California sea lions and seals. Middle Island is home to a small colony of northern elephant seals. == References ==