San Benedicto , formerly Isla de los Inocentes , is an uninhabited island, and third largest island of the Revillagigedo Islands , located in the Pacific Ocean .
124-490: It is 4.8 km by 2.4 km in size, with an area 10 km². It is of volcanic origin. It has two prominent peaks. The tallest peak, Bárcena, rises to a height of 332 metres (1,089 feet) near the southern part of the island. It forms a typical volcanic crater . It is located between the remains of two older craters, Herrera in the middle of the island and the Montículo Cinerítico ("Ash Heap") in
248-583: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. Brown pelican The brown pelican ( Pelecanus occidentalis ) is a bird of the pelican family, Pelecanidae , one of three species found in the Americas and one of two that feed by diving into water. It is found on the Atlantic Coast from New Jersey to
372-886: A mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from
496-498: A broad, silver–gray central area. The tail is dark gray with a variable silvery cast. The lower mandible is blackish, with a greenish-black gular pouch at the bottom for draining water when it scoops out prey. The breast and belly are dark, and the legs and feet black. It has a grayish white bill tinged with brown and intermixed with pale carmine spots. The crest is short and pale reddish-brown in color. The back, rump, and tail are streaked with gray and dark brown, sometimes with
620-418: A brown pelican (voiced by Geoffrey Rush in an Australian accent) was illustrated as a friendly, virtuous talking character named Nigel. Since 1988, the brown pelican has been rated as least concern on the IUCN Red List of Endangered species based on its large range—greater than 20,000 km (7700 mi )—and an increasing population trend. The population size is also well beyond
744-461: A clade comprising all the white-plumaged pelicans analyzed, including American white pelican (although the relationships among the latter group differed). With better genetic data and more modern methods, a new phylogenetic hypothesis of pelican relationships has arisen, which contrasts with the traditional view of brown and Peruvian being the most divergent pelicans based on their distinctive plumage and behavior (and early molecular data). Rather than
868-417: A clutch, and only one brood is raised per year. The egg is chalky white, and can measure about 76 mm (3.0 in) in length and 51 mm (2.0 in) in width. Incubation takes 28 to 30 days with both sexes sharing duties, keeping the eggs warm by holding them on or under their webbed feet. It takes 28 to 30 days for the eggs to hatch, and about 63 days to fledge . After that, the juvenile leave
992-651: A common prey item for North American river otters . The invasive red imported fire ant is known to prey on hatchlings. Like all pelicans, brown pelicans are highly sensitive to disturbances by humans (including tourists or fishermen) at their nests, and may even abandon their nests. Due to their size, non-nesting adults are rarely predated. Brown pelicans have several parasitic worms such as Petagiger , Echinochasmus , Phagicola longus , Mesostephanus appendiculatoides , Contracaecum multipapillatum , and Contracaecum bioccai , from its prey diet of black mullets , white mullets , and other fish species. The brown pelican
1116-478: A consistent decrease in the Pacific sardine population beginning as early as 2014. In 2019 these declines were found to have reached levels which were a mere 10% of the highest reported abundances. Fluctuations in sardine populations have largely been attributed to bottom-up control, primarily including climate variability and ocean temperature. The significant decrease in pacific sardine population can be linked to
1240-418: A desire to drill for oil on a Louisiana marshland that was a habitat of the endangered brown pelican. In the same year, Jurassic Park showed a pod of brown pelicans at the end of the film. In 1998, American conductor David Woodard performed a requiem for a California brown pelican on the seaward limit of the berm of a beach where the animal had fallen. In the 2003 Disney / Pixar film Finding Nemo ,
1364-488: A distance of just 1 m (3.3 ft) from each other. They are usually built by the female from reeds, leaves, pebbles, and sticks, and consist of feather-lined impressions protected with a 10 to 25 cm (3.9 to 9.8 in) rim of soil and debris. They are usually found 0.9 to 3 m (3 to 10 ft) above the ground. Renesting may occur if eggs are lost from the nest early in the breeding season. There are usually two to three, or sometimes even four, oval eggs in
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#17327718230191488-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,
1612-725: A low croak, while young frequently squeal. The brown pelican lives on the Atlantic, Gulf, and Pacific Coasts in the Americas. On the Atlantic Coast, it is found from the New Jersey coast to the mouth of the Amazon River . Along the Pacific Coast , it is found from British Columbia to northern Peru, including the Galapagos Islands . After nesting, North American birds move in flocks further north along
1736-416: A major food source which can compose up to 26% of their diet, making them one of the top three predators of sardines in the area. Non-fish prey includes crustaceans , especially prawns , and it occasionally feeds on amphibians and the eggs and nestlings of birds ( egrets , common murres and its own species ). As the brown pelican flies at a maximum height of 18 to 21 m (60 to 70 ft) above
1860-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano
1984-441: A rusty hue. The male and female are similar, but the female is slightly smaller. It is exceptionally buoyant due to the internal air sacks beneath its skin and in its bones. It is as graceful in the air as it is clumsy on land. The nonbreeding adult has a white head and neck, and the pre-breeding adult has a creamy yellow head. The pink skin around the eyes becomes dull and gray in the non-breeding season. It lacks any red hue, and
2108-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa
2232-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on
2356-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while
2480-427: A whitish band at the center. The irides are dark brown and the facial skin is bluish. It has a gray bill which is horn-yellow to orange near the tip, with a dark gray to pinkish-gray pouch. It acquires adult plumage at over 3 years of age, when the feathers on the neck become paler, the upperparts become striped, the greater upperwing and median coverts become grayer, and the belly acquires dark spots. The brown pelican
2604-408: A yellowish wash on the crown. The nape and neck are dark maroon–brown. The upper sides of the neck have white lines along the base of the gular pouch , and the lower foreneck has a pale yellowish patch. The feathers at the center of the nape are elongated, forming short, deep chestnut crest feathers . It has a silvery gray mantle , scapulars , and upperwing coverts (feathers on
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#17327718230192728-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in
2852-468: Is a popular scuba diving destination known for underwater encounters with dolphins, sharks, giant manta rays and other pelagics. An area called "The Boiler" is where divers commonly interact with the rays. Divers have also spotted tiger sharks , Galápagos sharks , silky sharks , and humpback whales here. Since there is no public airport on the island, divers visit here aboard dive vessels. The most popular months to visit are between November and July when
2976-417: Is a very gregarious bird; it lives in flocks of both sexes throughout the year. In level flight, brown pelicans fly in groups, with their heads held back on their shoulders and their bills resting on their folded necks. They may fly in a V formation , but usually in regular lines or single file, often low over the water's surface. To exclude water from the nasal passage, they have narrower internal regions of
3100-750: Is also found in mangrove swamps , and prefers shallow waters, especially near salty bays and beaches. It avoids the open sea, seldom venturing more than 20 miles from the coast. Some immature birds may stray to inland freshwater lakes. Its range may also overlap with the Peruvian pelican in some areas along the Pacific coast of South America . It roosts on rocks, water, rocky cliffs, piers, jetties, sand beaches, and mudflats. Most brown pelican populations are resident (nonmigratory) and dispersive (species moving from its birth site to its breeding site, or its breeding site to another breeding site). Some migration
3224-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where
3348-565: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in
3472-413: Is difficult to monitor and obtain indicators for. Since lacking food availability has negative implications for breeding success in seabirds, seabird diet, and breeding success have been used to indirectly measure the population status of the fish they feed on. This model has been shown to work using brown pelicans as an indicator species. As the proportion of sardines in the brown pelican's diet decreases,
3596-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for
3720-532: Is fairly common along the coast of California, South Carolina , North Carolina , Georgia , the West Indies, and many Caribbean islands as far south as Guyana . Along the Gulf Coast , it inhabits Alabama , Texas , Florida , Mississippi , Louisiana , and Mexico. The brown pelican is a strictly marine species, primarily inhabiting marine subtidal , warm estuarine , and marine pelagic waters. It
3844-594: Is greatly reduced by oceanic anomalies, specifically warm-phase anomalies that increase the intensity of upwellings. Increased upwellings disrupt marine productivity and forage fish availability. These trends have important implications for the health and conservation of brown pelicans, as well as other seabirds. Seabirds have become increasingly important as an indicator species . They are often used in order to indirectly track changes in fish stocks, ecosystem health, and climate change . Environmental changes tend to have fast acting impacts on marine bird populations due to
San Benedicto Island - Misplaced Pages Continue
3968-704: Is now a staple of crowded coastal regions and is at some risk by fishermen (monofilament fishing line and hooks) and boaters. In the early twentieth century, hunting was a major cause of its death, and people still hunt adults for their feathers and collect eggs on the Caribbean coasts, in Latin America , and occasionally in the United States, even though it is protected under the Migratory Bird Treaty Act of 1918 . The brown pelican
4092-540: Is observed, especially in the northern parts of the species's range, but these movements are often erratic, depending on local conditions. While usually restricted to coastal regions, brown pelicans occasionally wander inland, and there are records of vagrant individuals across much of the interior of North America. The species also occasionally wanders along the coasts of the Americas outside its normal range, with vagrants reported as far north as Southeast Alaska and Newfoundland , as far south as central Chile (well into
4216-407: Is occasional at colonies, and predators of eggs and young (usually small nestlings are threatened but also occasionally up to fledgling size depending on the size of the predator) can include gulls , raptors (especially bald eagles ), spiny-tailed iguanas , alligators , vultures , feral cats , feral dogs , raccoons , fish crows , and corvids . Predation is likely reduced if the colony
4340-484: Is on an island. Although it is rare, bobcats have been documented eating both the offspring and injured adults. Predation on adult brown pelicans is rarely reported, but cases where they have fallen prey to bald eagles have been reported. Also, South American sea lions and unidentified large sharks have been observed to prey on adult brown pelicans by seizing them from beneath while the birds are sitting on ocean waters. In California, adult brown pelicans have become
4464-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near
4588-478: Is readily distinguished from the American white pelican by its nonwhite plumage, smaller size, and habit of diving for fish from the air, as opposed to co-operative fishing from the surface. It and the Peruvian pelican are the only true marine pelican species. The brown pelican produces a wide variety of harsh, grunting sounds, such as a low-pitched hrrraa-hrra , during displays. The adult also rarely emits
4712-505: Is the national bird of Saint Martin , Barbados , Saint Kitts and Nevis , and the Turks and Caicos Islands . In 1902, it was made a part of the official Louisiana seal and, in 1912, a pelican and her young became part of the Flag of Louisiana as well. One of Louisiana's state nicknames is "The Pelican State", and the brown pelican is the official state bird of Louisiana. It is one of
4836-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in
4960-604: The California current system, leading to lasting impacts on Pacific sardine productivity and reproductive success . The brown pelican has been predicted to have high vulnerability to declining sardine populations . At the lowest levels of sardine abundance, the brown pelican population has been predicted to decline up to 50%. Even with a more moderate decline in sardine abundance (50% relative abundance), brown pelicans have been predicted to decrease by up to 27%. A recent decline in brown pelican breeding success coincides with
5084-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off
San Benedicto Island - Misplaced Pages Continue
5208-573: The Deepwater Horizon oil spill has adversely affected populations, and current population figures are not available. The brown pelican abundance has steadily recovered from the drastic population decreases in the 1940s, however bottom up control threatens the Southern California populations as food sources become diminished. It is common for forage fish populations to experience regular fluctuations, however there has been
5332-550: The Louisiana Department of Wildlife and Fisheries ' reintroduction program re-established the brown pelican, and its population numbers in California and Texas were restored due to improved reproduction and natural recolonization of the species. By 1985, its population in the eastern United States, including Florida , Georgia , South Carolina , Alabama , and northward along the Atlantic Coast, had recovered and
5456-606: The Santo Tomás of Grijalva (present day Socorro Island ). Bárcena's only historic eruption began around 8:30 AM on August 1, 1952, from the El Boquerón vent. In a severe Vulcanian eruption of magnitude 3 on the Volcanic Explosivity Index scale, pyroclastic flows rolled over the island. Soon the entire island was covered in ash and pumice up to 3 m (10 ft) high. Ejecta filled
5580-804: The core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,
5704-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when
5828-498: The 1952 eruption. The local plant life contains several Revillagigedo endemics shared with Clarión: Bulbostylis nesiotica , Cyperus duripes and Perityle socorrosensis . The taxonomic status of the local Euphorbia anthonyi is not fully resolved. Other plants on San Benedicto are Aristolochia islandica , Cenchrus myosuroides , Eragrostis diversiflora , Erigeron crenatus , Ipomoea pes-caprae subsp. brasiliensis and Teucrium townsendii . San Benedicto Island
5952-493: The American white pelican and the more distantly related great white pelican . ) In 1932, James L. Peters divided Pelecanus into three subgenera, placing brown pelican (including Peruvian pelican) in a monospecific Leptopelicanus , American white pelican in a monospecific Cyrtopelicanus , and all the rest in the subgenus Pelecanus , a treatment which was also followed by Jean Dorst and Raoul J. Mougin in 1979. Andrew Elliott in 1992, and Joseph B. Nelson in 2005, considered
6076-631: The Americas were colonized relatively late in pelican evolution, with the family originating in Africa or South Asia; however, he later supported the prevailing view that brown (with Peruvian) was the most divergent pelican (and considered American white and great white pelicans to be close relatives, implying two independent dispersals of pelicans into the Americas, with that of the ancestor of brown and Peruvian pelicans occurring early on). Sibley and Ahlquist 's DNA-DNA hybridization studies and UPGMA tree published in 1990 supported brown pelican as sister to
6200-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like
6324-613: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in
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#17327718230196448-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to
6572-771: The brown pelican population had drastically declined due to a lack of breeding success. By the 1960s, it had almost disappeared along the Gulf Coast and, in southern California , it had suffered almost total reproductive failure, due to DDT usage in the United States. The brown pelican was listed under the United States Endangered Species Act from 1970 to 2009. A research group from the University of Tampa , headed by Ralph Schreiber, conducted research in Tampa Bay , and found that DDT caused
6696-456: The brown-plumaged pelicans and white-plumaged pelicans forming two reciprocally monophyletic groups, the American white pelican is sister to brown and Peruvian pelicans, the three together forming an exclusively New World pelican clade. (Among the other pelicans, pink-backed, Dalmatian, and spot-billed pelicans are close relatives, together sister to Australian pelican. Great white pelican has no particularly close relatives; while it may be sister to
6820-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down
6944-466: The coasts, returning to warmer waters for winter. In the non-breeding season, it is found as far north as Canada. It is a rare and irregular visitor south of Piura in Peru, where generally it is replaced by the Peruvian pelican, and can occur as a non-breeding visitor south at least to Ica during El Niño years. Small numbers of brown pelicans have been recorded from Arica in far northern Chile . It
7068-433: The crater and at the rift in its base; the lava was hard but still retained much heat. By late 1953, the volcano was dormant again. The eruption wiped out – at least temporarily – all flora and terrestrial fauna of San Benedicto. The fauna included the endemic San Benedicto rock wren which became extinct around 9 AM on August 1. It is unusual for an extinction to be recorded with such precision, and in this case it
7192-431: The deepest division among pelicans to lie between brown (plus Peruvian) pelican on the one hand, and the white-plumaged pelicans on the other (among which the large ground-nesting American white, Australian , great white, and Dalmatian pelicans were thought to form a clade, and the smaller tree-nesting pink-backed and spot-billed pelicans were likewise considered sister taxa). In 1993, Paul Johnsgard hypothesized that
7316-799: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in
7440-412: The eruption or, more probably, recolonized the island; their larvae live in the ocean. Still, the island was devoid of plant life. By late 1953, rain had removed the ash and pumice deposits in the steeper places of northern San Benedicto. At least half the previously recorded plant taxa were again present. Numerous seabirds were found breeding, most north of Herrera but a colony of blue-footed boobies
7564-827: The female is slightly smaller. The nonbreeding adult has a white head and neck. The pink skin around the eyes becomes dull and gray in the nonbreeding season. It lacks any red hue, and the pouch is strongly olivaceous ochre-tinged and the legs are olivaceous gray to blackish-gray. The brown pelican mainly feeds on fish, but occasionally eats amphibians , crustaceans , and the eggs and nestlings of birds. It nests in colonies in secluded areas, often on islands, vegetated land among sand dunes, thickets of shrubs and trees, and mangroves . Females lay two or three oval, chalky white eggs. Incubation takes 28 to 30 days with both sexes sharing duties. The newly hatched chicks are pink, turning gray or black within 4 to 14 days. About 63 days are needed for chicks to fledge . Six to 9 weeks after hatching,
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#17327718230197688-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from
7812-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which
7936-421: The frigatebirds, the island might be highly suitable for establishing a new colony. Indeed, it bred here before the 1952 eruption; shearwaters are highly conservative in choosing their breeding locations, which explains why San Benedicto has not yet been recolonized. Vagrants of other species, such as brown pelicans , red-tailed hawks , ospreys , barn swallows and bay-breasted warblers may occasionally visit
8060-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in
8184-466: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in
8308-470: The high capacity of their salt glands to excrete salt. The brown pelican is a monogamous breeder within a breeding season, but does not pair for life . Nesting season peaks during March and April. The male chooses a nesting site and performs a display of head movements to attract a female. At the proposed nest site, major courtship displays such as head swaying, bowing, turning, and upright (standing on its legs without any support) are performed by both
8432-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include
8556-443: The island but ultimately move on or perish, finding San Benedicto still too barren to support a resident population. Migrant waders , such as Hudsonian curlews and wandering tattlers , use San Benedicto for brief stopovers more regularly. A mere 10 plant taxa have been recorded from San Benedicto, containing mainly herbs and grasses , with the occasional subshrubs and vines . It does not appear that any became extinct due to
8680-488: The juveniles leave the nest, and gather into small groups known as pods. The brown pelican is the national bird of Saint Martin , Barbados , Saint Kitts and Nevis , and the Turks and Caicos Islands , and the official state bird of Louisiana , appearing on the flag, seal, or coat of arms of each. It has been rated as a species of least concern by the International Union for Conservation of Nature . It
8804-451: The levels of nitrogen within their habitat, a limiting factor in plankton production. Pacific sardines in the California current system rely on wind driven upwelling to push cooler, nitrogen rich waters towards the surface, maintaining a sustainable, nutrient abundant environment. Continued environmental disruptions, such as El Niño , rising ocean temperatures, and increased commercial fishing, have drastic effects on nutrient cycling within
8928-484: The mandible. The juvenile is similar, but is grayish-brown overall and has paler underparts. The head, neck, and thighs are dusky-brown, and the abdomen is dull white. The plumage of the male is similar to a fully adult female, although the male's head feathers are rather rigid. The tail and flight feathers are browner than those of the adult. It has short, brown upperwing coverts, which are often darker on greater coverts, and dull brownish-gray underwing coverts with
9052-437: The mascots of Tulane University , present on its seal, and is also present on the crest of the University of the West Indies . The National Basketball Association (NBA)'s New Orleans Pelicans are named in the honor of the brown pelican. In the 1993 film The Pelican Brief , based on the novel of the same name by John Grisham , a legal brief speculates that the assassins of two supreme court justices were motivated by
9176-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of
9300-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius
9424-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of
9548-455: The mouth of the Amazon River , and along the Pacific Coast from British Columbia to Peru, including the Galapagos Islands . The nominate subspecies in its breeding plumage has a white head with a yellowish wash on the crown. The nape and neck are dark maroon–brown. The upper sides of the neck have white lines along the base of the gular pouch , and the lower fore neck has a pale yellowish patch. The male and female are similar, but
9672-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma
9796-422: The nest and gather into small groups known as pods. The newly hatched chicks are pink and weigh about 60 g (0.13 lb). Within 4 to 14 days, they turn gray or black. After that, they develop a coat of white, black or grayish down. Fledging success may be as high as 100% for the first hatched chick, 60% for the second chick, and just 6% for the third chick. The parents regurgitate predigested food for
9920-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of
10044-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio
10168-450: The northeastern edge of the archipelago makes San Benedicto the north(east)ernmost location where several seabirds of the tropical Eastern Pacific come to breed. Taxa breeding on San Benedicto are: The nearly extinct Townsend's shearwater ( Puffinus auricularis ) does not seem to breed on San Benedicto, but can sometimes be seen feeding offshore. Given that there are no invasive species on San Benedicto and also no predators apart from
10292-550: The nostrils. The brown pelican is a piscivore , primarily feeding on fish. Menhaden may account for 90% of its diet, and the anchovy supply is particularly important to the brown pelican's nesting success. Other fish preyed on with some regularity includes pigfish , pinfish , herring , sheepshead , silversides , mullets , sardines , minnows , and topminnows . Brown pelicans residing in Southern California rely especially heavily on pacific sardine as
10416-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by
10540-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break
10664-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb
10788-401: The ocean, it can spot schools of fish while flying. When foraging, it dives bill-first like a kingfisher , often submerging completely below the surface momentarily as it snaps up prey. Besides its sister species, the Peruvian pelican, this is the only pelican to primarily forage via diving, all other extant pelican merely float on the waters' surface when foraging. Upon surfacing, it spills
10912-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as
11036-399: The outermost, largest, row of upperwing coverts) are blackish, with the primaries having white shafts and the secondaries having variable silver-gray fringes. The tertials (feathers arising in the brachial region) are silver-gray with a brownish tinge. The underwing has grayish-brown remiges with white shafts to the outer primary feathers. The axillaries and covert feathers are dark, with
11160-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as
11284-590: The pelican eggshells to be too thin to support the embryo to maturity. In 1972, the United States Environmental Protection Agency (USEPA) banned DDT usage in the United States and limited the use of other pesticides. There has been a decline in chemical contaminant levels in brown pelican eggs since then, and a corresponding increase in its nesting success. It became extinct in 1963 in Louisiana . Between 1968 and 1980,
11408-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under
11532-401: The population decline of the Pacific sardine. Between 2014 and 2016, brown pelicans experienced a continuous breeding failure. These breeding failures have been characterized by decreased numbers of pelicans arriving at nesting colonies, large scale abandonment and early migration due to an inability to feed hatchlings, and sub-optimal breeding by those who do attempt to breed. Breeding success
11656-409: The pouch is strongly olivaceous ochre tinged and the legs are olivaceous gray to blackish-gray. It has pale blue to yellowish white irides which become brown during the breeding season. During courtship, the bill becomes pinkish red to pale orange, redder at the tip, and the pouch is blackish. Later in the breeding season the bill becomes pale ash-gray over most of the upper jaw and the basal third of
11780-470: The previous four, this relationship had low statistical support.) The brown pelican is the smallest of the eight extant pelican species, but is often one of the larger seabirds in their range nonetheless. It measures 1 to 1.52 m (3 ft 3 in to 5 ft 0 in) in length and has a wingspan of 2.03 to 2.28 m (6 ft 8 in to 7 ft 6 in). The weight of adults can range from 2 to 5 kg (4.4 to 11.0 lb), about half
11904-761: The range of the closely related Peruvian pelican), and as far east in South America as Alagoas . Rare inland vagrants, generally caused by hurricanes or El Niño phenomena, have been reported from the Colombian Andes . They were first recorded in July 2009 in the Interandean Valley , where they remained for at least 161 days. There are four records far inland in Amazônia Legal , along the Amazon River and its tributaries. The brown pelican
12028-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon
12152-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above
12276-588: The sexes. They may also be accompanied by low raaa calls. Once a pair forms a bond, overt communication between them is minimal. It is a colonial species, with some colonies maintained for many years. Probably owing to disturbance, tick infestation , or alteration in food supply, colonies frequently shift. It nests in secluded area, often on islands, vegetated spots among sand dunes, thickets of shrubs and trees, and in mangroves , although sometimes on cliffs, and less often in bushes or small trees. Nesting territories are clumped, as individual territories may be at
12400-494: The simplicity of their trophic cascade , allowing for complex, long term trends in ecosystem health and resources to be easily realized and tracked. Brown pelicans have proven to be a useful indicator in determining the effects of the well-established fishing industry in Southern California. Sardine fishery in the Gulf of California has been showing signs of overfishing since the early 1990s. Sardine population and abundance, however,
12524-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism
12648-525: The southwest. There is no permanent source of freshwater . The first recorded sighting of San Benedicto was by the Spanish expedition of Hernando de Grijalva on 28 December 1533 that charted it as Isla de los Inocentes due to this day being the festivity of the Holy Innocents . In November 1542, it was sighted again by the expedition of Ruy López de Villalobos that incorrectly identified it with
12772-551: The species from hunters. The brown pelican was described by Swedish zoologist Carl Linnaeus in the 1766 12th edition of his Systema Naturae , where it was given the binomial name of Pelecanus occidentalis. It belongs to the New World clade of the genus Pelecanus . Five subspecies of the brown pelican are recognized. At least some of these subspecies are genetically distinct despite similar phenotypes . The subspecies differ from one another in size, coloration of
12896-779: The species was removed from the Endangered Species List. Its population has grown by about 68% per decade over a period of 40 years in North America, and this trend appears to be continuing. It is still listed as endangered in the Pacific Coast region of its range and in the southern and central United States. Although the United States Gulf Coast populations in Louisiana and Texas are still listed as endangered, they were recently estimated in 2009 about 12,000 breeding pairs. Since that time
13020-680: The success of fisheries declines to a lesser extent. When eventually the sardine abundance has declined enough for brown pelicans to move away and begin feeding on other forage fish, commercial fishing still would be fishing in significant numbers. This indicates that even when fisheries are not seeing signs of declining sardine abundance, brown pelicans may have already been affected to the point of locating other food sources. This availability of sardines may decline even further during El Niño anomalies, when thermoclines prevent brown pelicans from reaching their prey. Brown pelican diet will mostly indicate declines in sardine abundance for fisheries during
13144-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into
13268-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath
13392-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where
13516-406: The threshold for vulnerable species . The nominate race population is thought to number at least 290,000 in the West Indies, and 650,000 globally. In 1903, Theodore Roosevelt set aside Pelican Island , now known as Pelican Island National Wildlife Refuge, to solely protect the brown pelican from hunters. Starting in the 1940s with the invention and extensive use of pesticides such as DDT ,
13640-455: The throat pouch (among other bare parts) in breeding condition, and/or certain breeding plumage details, as well as geographic range. The brown pelican is part of a clade that includes the Peruvian pelican ( P. thagus ) and American white pelican ( P. erythrorhynchos ); brown and Peruvian pelicans are sister taxa, with American white pelican a more distant relative. The Peruvian pelican
13764-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in
13888-435: The upper side of the wings), with a brownish tinge. The lesser coverts have dark bases, which gives the leading edge of the wing a streaky appearance. The uppertail coverts (feathers above the tail) are silvery white at the center, forming pale streaks. The median (between the greater and the lesser coverts), primary (connected to the distal forelimb ), secondary (connected to the ulna ), and greater coverts (feathers of
14012-447: The valley between Herrera crater and Montículo Cinerítico, and by August 14 had formed a cone some 300 m (over 1000 ft) high. After some months with little activity, a second series of eruptions began on November 1, 1952. On December 8, the magma broke through the cone's southeastern base and started to flow into the sea. This continued to about February 24, 1953. By March 9, 1953, most activity had subsided, except fumaroles in
14136-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of
14260-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of
14384-467: The water from its throat pouch before swallowing its catch. Only the Peruvian pelican shares this active foraging style (although that species never dives from such a great height ), while other pelicans forage more inactively by scooping up corralled fish while swimming on the water surface. It is an occasional target of kleptoparasitism by other fish-eating birds such as gulls , skuas , and frigatebirds . They are capable of drinking saline water due to
14508-513: The weather and seas are calmer. Volcano A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example,
14632-471: The weight of the other pelicans found in the Americas, the Peruvian and American white pelicans. The average weight in Florida of 47 females was 3.17 kg (7.0 lb), while that of 56 males was 3.7 kg (8.2 lb). Like all pelicans, it has a very long bill , measuring 280 to 348 mm (11.0 to 13.7 in) in length. The nominate subspecies in its breeding plumage has a white head with
14756-647: The young to feed upon until they reach their fledging stage. After about 35 days, the young venture out of the nest by walking. The young start flying about 71 to 88 days after hatching. The adults remain with them until some time afterwards and continue to feed them. In the 8- to 10-month period during which they are cared for, the nestling pelicans are fed by regurgitated, partially digested food of around 70 kg (150 lb) of fish. The young reach sexual maturity (and full adult plumage) at anywhere from three to five years of age. A brown pelican has been recorded to have lived for over 31 years in captivity. Predation
14880-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in
15004-597: Was listed under the United States Endangered Species Act from 1970 to 2009, as pesticides such as dieldrin and DDT threatened its future in the Southeastern United States and California . In 1972, the use of DDT was banned in Florida , followed by the rest of the United States. Since then, the brown pelican's population has increased. In 1903, Theodore Roosevelt set aside the first National Wildlife Refuge , Florida's Pelican Island , to protect
15128-429: Was only possible because observers were offshore, documenting how the island was blasted with ejecta. However, once the volcanic activity had died down by the spring of 1953, seabirds returned to the island for the breeding season. They roosted only north of Herrera crater, where the ash cover had already begun to erode away. A few Johngarthia planata land crabs were present also, having either managed to survive
15252-463: Was present in the ditch between Herrera and Barcena. The vertebrate fauna of San Benedicto is nowadays composed entirely of seabirds. It appears that the Revillagigedo population of western ravens also bred on San Benedicto before the 1952 eruption, but any such population was wiped out and ravens are not found – except maybe as very rare vagrants – on San Benedicto today. Its position on
15376-400: Was previously considered a subspecies of the brown pelican, but is now considered a separate species on the basis of its much greater size (around double the weight of the brown pelican), differences in bill color and plumage, and a lack of evidence of hybridization between the forms where their ranges approach and overlap. (In captivity, the brown pelican is known to have hybridized with both
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