130-557: Moris Gannets are seabirds comprising the genus Morus in the family Sulidae , closely related to boobies . They are known as 'solan' or 'solan goose' in Scotland. A common misconception is that the Scottish name is 'guga' but this is the Gaelic name referring to the chicks only. Gannets are large white birds with yellowish heads, black-tipped wings and long bills. Northern gannets are
260-447: A murre colony. In most seabird colonies, several different species will nest on the same colony, often exhibiting some niche separation . Seabirds can nest in trees (if any are available), on the ground (with or without nests ), on cliffs, in burrows under the ground and in rocky crevices. Competition can be strong both within species and between species, with aggressive species such as sooty terns pushing less dominant species out of
390-401: A wreck . Seabirds have had a long association with both fisheries and sailors , and both have drawn benefits and disadvantages from the relationship. Fishermen have traditionally used seabirds as indicators of both fish shoals , underwater banks that might indicate fish stocks, and of potential landfall. In fact, the known association of seabirds with land was instrumental in allowing
520-601: A clade, the Aequornithes either became seabirds in a single transition in the Cretaceous or some lineages such as pelicans and frigatebirds adapted to sea living independently from freshwater-dwelling ancestors. In the Paleogene both pterosaurs and marine reptiles became extinct, allowing seabirds to expand ecologically. These post-extinction seas were dominated by early Procellariidae , giant penguins and two extinct families ,
650-535: A colony. Eggers from San Francisco took almost half a million eggs a year from the Farallon Islands in the mid-19th century, a period in the islands' history from which the seabird species are still recovering. Both hunting and egging continue today, although not at the levels that occurred in the past, and generally in a more controlled manner. For example, the Māori of Stewart Island / Rakiura continue to harvest
780-467: A constant rate. These " molecular clocks ", however, are fallible, and provide only approximate timing: for example, they are not sufficiently precise and reliable for estimating when the groups that feature in the Cambrian explosion first evolved, and estimates produced by different techniques may vary by a factor of two. Organisms are only rarely preserved as fossils in the best of circumstances, and only
910-486: A fashion similar to grebes and loons (using its feet to move underwater) but had a beak filled with sharp teeth. Flying Cretaceous seabirds do not exceed wingspans of two meters; any sizes were taken by piscivorous pterosaurs . While Hesperornis is not thought to have left descendants, the earliest modern seabirds also occurred in the Cretaceous, with a species called Tytthostonyx glauconiticus , which has features suggestive of Procellariiformes and Fregatidae. As
1040-712: A few dozen birds to millions. Many species are famous for undertaking long annual migrations , crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even on each other. Seabirds can be highly pelagic , coastal, or in some cases spend a part of the year away from the sea entirely. Seabirds and humans have a long history together: They have provided food to hunters , guided fishermen to fishing stocks, and led sailors to land. Many species are currently threatened by human activities such as oil spills , nets, climate change and severe weather. Conservation efforts include
1170-426: A fraction of such fossils have been discovered. This is illustrated by the fact that the number of species known through the fossil record is less than 5% of the number of known living species, suggesting that the number of species known through fossils must be far less than 1% of all the species that have ever lived. Because of the specialized and rare circumstances required for a biological structure to fossilize, only
1300-495: A hierarchical classification system still in use today. Darwin and his contemporaries first linked the hierarchical structure of the tree of life with the then very sparse fossil record. Darwin eloquently described a process of descent with modification, or evolution, whereby organisms either adapt to natural and changing environmental pressures, or they perish. When Darwin wrote On the Origin of Species by Means of Natural Selection, or
1430-936: A large number of non-governmental organizations (including BirdLife International , the American Bird Conservancy and the Royal Society for the Protection of Birds ). This led to the Agreement on the Conservation of Albatrosses and Petrels , a legally binding treaty designed to protect these threatened species, which has been ratified by thirteen countries as of 2021 (Argentina, Australia, Brazil, Chile, Ecuador, France, New Zealand, Norway, Peru, South Africa, Spain, Uruguay, United Kingdom). Many seabirds are little studied and poorly known because they live far out at sea and breed in isolated colonies. Some seabirds, particularly
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#17328521752551560-555: A lineage— Eurypygimorphae —that is a sister group to the Aequornithes. Seabirds, by virtue of living in a geologically depositional environment (that is, in the sea where sediments are readily laid down), are well represented in the fossil record. They are first known to occur in the Cretaceous period, the earliest being the Hesperornithiformes , like Hesperornis regalis , a flightless loon-like seabird that could dive in
1690-418: A mid-Ordovician age. Such index fossils must be distinctive, be globally distributed and occupy a short time range to be useful. Misleading results are produced if the index fossils are incorrectly dated. Stratigraphy and biostratigraphy can in general provide only relative dating ( A was before B ), which is often sufficient for studying evolution. However, this is difficult for some time periods, because of
1820-576: A million birds have been recorded, both in the tropics (such as Kiritimati in the Pacific ) and in the polar latitudes (as in Antarctica ). Seabird colonies occur exclusively for the purpose of breeding; non-breeding birds will only collect together outside the breeding season in areas where prey species are densely aggregated. Seabird colonies are highly variable. Individual nesting sites can be widely spaced, as in an albatross colony, or densely packed as with
1950-526: A mutation first appeared. Phylogenetics and paleontology work together in the clarification of science's still dim view of the appearance of life and its evolution. Niles Eldredge 's study of the Phacops trilobite genus supported the hypothesis that modifications to the arrangement of the trilobite's eye lenses proceeded by fits and starts over millions of years during the Devonian . Eldredge's interpretation of
2080-414: A place for returning mates to reunite, and reduces the costs of prospecting for a new site. Young adults breeding for the first time usually return to their natal colony, and often nest close to where they hatched. This tendency, known as philopatry , is so strong that a study of Laysan albatrosses found that the average distance between hatching site and the site where a bird established its own territory
2210-570: A portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates , or the chitinous or calcareous exoskeletons of invertebrates . Fossils may also consist of the marks left behind by the organism while it was alive, such as animal tracks or feces ( coprolites ). These types of fossil are called trace fossils or ichnofossils , as opposed to body fossils . Some fossils are biochemical and are called chemofossils or biosignatures . Gathering fossils dates at least to
2340-438: A reduced capacity for powered flight and are dependent on a type of gliding called dynamic soaring (where the wind deflected by waves provides lift) as well as slope soaring. Seabirds also almost always have webbed feet , to aid movement on the surface as well as assisting diving in some species. The Procellariiformes are unusual among birds in having a strong sense of smell , which is used to find widely distributed food in
2470-400: A richly diverse assembly of early multicellular eukaryotes . The fossil record and faunal succession form the basis of the science of biostratigraphy or determining the age of rocks based on embedded fossils. For the first 150 years of geology , biostratigraphy and superposition were the only means for determining the relative age of rocks. The geologic time scale was developed based on
2600-448: A small percentage of life-forms can be expected to be represented in discoveries, and each discovery represents only a snapshot of the process of evolution. The transition itself can only be illustrated and corroborated by transitional fossils, which will never demonstrate an exact half-way point. The fossil record is strongly biased toward organisms with hard-parts, leaving most groups of soft-bodied organisms with little to no role. It
2730-461: A smaller layer of air (compared to other diving birds) but otherwise soak up water. This allows them to swim without fighting the buoyancy that retaining air in the feathers causes, yet retain enough air to prevent the bird losing excessive heat through contact with water. The plumage of most seabirds is less colourful than that of land birds, restricted in the main to variations of black, white or grey. A few species sport colourful plumes (such as
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#17328521752552860-575: A source of increasing concern to conservationists. The bycatch of seabirds entangled in nets or hooked on fishing lines has had a big impact on seabird numbers; for example, an estimated 100,000 albatrosses are hooked and drown each year on tuna lines set out by long-line fisheries. Overall, many hundreds of thousands of birds are trapped and killed each year, a source of concern for some of the rarest species (for example, only about 2,000 short-tailed albatrosses are known to still exist). Seabirds are also thought to suffer when overfishing occurs. Changes to
2990-403: A vast ocean, and help distinguish familiar nest odours from unfamiliar ones. Salt glands are used by seabirds to deal with the salt they ingest by drinking and feeding (particularly on crustaceans ), and to help them osmoregulate . The excretions from these glands (which are positioned in the head of the birds, emerging from the nasal cavity ) are almost pure sodium chloride . With
3120-400: A very variable prey source); this may be a reason why it arises more frequently in seabirds. There are other possible advantages: colonies may act as information centres, where seabirds returning to the sea to forage can find out where prey is by studying returning individuals of the same species. There are disadvantages to colonial life, particularly the spread of disease. Colonies also attract
3250-499: A voracious appetite. Gannets are colonial breeders on islands and coasts, normally laying one chalky-blue egg. They lack brood patches and use their webbed feet to warm the eggs. They reach maturity around 5 years of age. First-year birds are completely black, and subsequent subadult plumages show increasing amounts of white. The most important nesting ground for northern gannets is the United Kingdom, with about two-thirds of
3380-454: A year, unless they lose the first (with a few exceptions, like the Cassin's auklet ), and many species (like the tubenoses and sulids ) will only lay one egg a year. Care of young is protracted, extending for as long as six months, among the longest for birds. For example, once common guillemot chicks fledge , they remain with the male parent for several months at sea. The frigatebirds have
3510-449: Is a notable example of how knowledge encoded by the fossil record continues to contribute otherwise unattainable information on the emergence and development of life on Earth. For example, the research suggests Markuelia has closest affinity to priapulid worms, and is adjacent to the evolutionary branching of Priapulida , Nematoda and Arthropoda . Despite significant advances in uncovering and identifying paleontological specimens, it
3640-407: Is energetically inefficient in warmer waters. With their poor flying ability, many wing-propelled pursuit divers are more limited in their foraging range than other guilds. Gannets , boobies , tropicbirds , some terns, and brown pelicans all engage in plunge diving, taking fast-moving prey by diving into the water from the flight. Plunge diving allows birds to use the energy from the momentum of
3770-479: Is generally accepted that the fossil record is vastly incomplete. Approaches for measuring the completeness of the fossil record have been developed for numerous subsets of species, including those grouped taxonomically, temporally, environmentally/geographically, or in sum. This encompasses the subfield of taphonomy and the study of biases in the paleontological record. Paleontology seeks to map out how life evolved across geologic time. A substantial hurdle
3900-642: Is inconclusive. Some plunge divers (as well as some surface feeders) are dependent on dolphins and tuna to push shoaling fish up towards the surface. This catch-all category refers to other seabird strategies that involve the next trophic level up. Kleptoparasites are seabirds that make a part of their living stealing food of other seabirds. Most famously, frigatebirds and skuas engage in this behaviour, although gulls, terns and other species will steal food opportunistically. The nocturnal nesting behaviour of some seabirds has been interpreted as arising due to pressure from this aerial piracy. Kleptoparasitism
4030-657: Is known as the fossil record . Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of Tiktaalik in the arctic of Canada . Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. The observation in
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4160-545: Is not thought to play a significant part of the diet of any species, and is instead a supplement to food obtained by hunting. A study of great frigatebirds stealing from masked boobies estimated that the frigatebirds could at most obtain 40% of the food they needed, and on average obtained only 5%. Many species of gull will feed on seabird and sea mammal carrion when the opportunity arises, as will giant petrels . Some species of albatross also engage in scavenging: an analysis of regurgitated squid beaks has shown that many of
4290-402: Is often a problem as well—visitors, even well-meaning tourists, can flush brooding adults off a colony, leaving chicks and eggs vulnerable to predators. The build-up of toxins and pollutants in seabirds is also a concern. Seabirds, being apex predators , suffered from the ravages of the insecticide DDT until it was banned; DDT was implicated, for example, in embryo development problems and
4420-607: Is punished for killing an albatross by having to wear its corpse around his neck. Sailors did, however, consider it unlucky to touch a storm petrel, especially one that landed on the ship. Fossil record A fossil (from Classical Latin fossilis , lit. ' obtained by digging ' ) is any preserved remains, impression, or trace of any once-living thing from a past geological age . Examples include bones , shells , exoskeletons , stone imprints of animals or microbes , objects preserved in amber , hair , petrified wood and DNA remnants. The totality of fossils
4550-438: Is replete with the mollusks , the vertebrates , the echinoderms , the brachiopods and some groups of arthropods . Fossil sites with exceptional preservation—sometimes including preserved soft tissues—are known as Lagerstätten —German for "storage places". These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus slowing decomposition. Lagerstätten span geological time from
4680-484: Is some evidence of this, the effects of seabirds are considered smaller than that of marine mammals and predatory fish (like tuna ). Some seabird species have benefited from fisheries, particularly from discarded fish and offal . These discards compose 30% of the food of seabirds in the North Sea , for example, and compose up to 70% of the total food of some seabird populations. This can have other impacts; for example,
4810-589: Is the skimmer , which has a unique fishing method: flying along the surface with the lower mandible in the water—this shuts automatically when the bill touches something in the water. The skimmer's bill reflects its unusual lifestyle, with the lower mandible uniquely being longer than the upper one. Surface feeders that swim often have unique bills as well, adapted for their specific prey. Prions have special bills with filters called lamellae to filter out plankton from mouthfuls of water, and many albatrosses and petrels have hooked bills to snatch fast-moving prey. On
4940-448: Is the deepest diver of the shearwaters, having been recorded diving below 70 metres (230 ft). Some albatross species are also capable of limited diving, with light-mantled sooty albatrosses holding the record at 12 metres (40 ft). Of all the wing-propelled pursuit divers, the most efficient in the air are the albatrosses, and they are also the poorest divers. This is the dominant guild in polar and subpolar environments, but it
5070-470: Is the difficulty of working out fossil ages. Beds that preserve fossils typically lack the radioactive elements needed for radiometric dating . This technique is our only means of giving rocks greater than about 50 million years old an absolute age, and can be accurate to within 0.5% or better. Although radiometric dating requires careful laboratory work, its basic principle is simple: the rates at which various radioactive elements decay are known, and so
5200-413: Is the science of deciphering the "layer-cake" that is the sedimentary record. Rocks normally form relatively horizontal layers, with each layer younger than the one underneath it. If a fossil is found between two layers whose ages are known, the fossil's age is claimed to lie between the two known ages. Because rock sequences are not continuous, but may be broken up by faults or periods of erosion , it
5330-459: Is very difficult to match up rock beds that are not directly adjacent. However, fossils of species that survived for a relatively short time can be used to match isolated rocks: this technique is called biostratigraphy . For instance, the conodont Eoplacognathus pseudoplanus has a short range in the Middle Ordovician period. If rocks of unknown age have traces of E. pseudoplanus , they have
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5460-757: The Cambrian period to the present . Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan Shales and Burgess Shale , the Devonian Hunsrück Slates , the Jurassic Solnhofen Limestone , and the Carboniferous Mazon Creek localities. A fossil is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, such as from aragonite to calcite . Replacement occurs when
5590-684: The Pelagornithidae and the Plotopteridae (a group of large seabirds that looked like the penguins). Modern genera began their wide radiation in the Miocene , although the genus Puffinus (which includes today's Manx shearwater and sooty shearwater ) might date back to the Oligocene . Within the Charadriiformes, the gulls and allies ( Lari ) became seabirds in the late Eocene, and then waders in
5720-581: The Phacops fossil record was that the aftermaths of the lens changes, but not the rapidly occurring evolutionary process, were fossilized. This and other data led Stephen Jay Gould and Niles Eldredge to publish their seminal paper on punctuated equilibrium in 1971. Synchrotron X-ray tomographic analysis of early Cambrian bilaterian embryonic microfossils yielded new insights of metazoan evolution at its earliest stages. The tomography technique provides previously unattainable three-dimensional resolution at
5850-692: The Polynesians to locate tiny landmasses in the Pacific. Seabirds have provided food for fishermen away from home, as well as bait. Famously, tethered cormorants have been used to catch fish directly. Indirectly, fisheries have also benefited from guano from colonies of seabirds acting as fertilizer for the surrounding seas. Negative effects on fisheries are mostly restricted to raiding by birds on aquaculture , although long-lining fisheries also have to deal with bait stealing. There have been claims of prey depletion by seabirds of fishery stocks, and while there
5980-559: The Renaissance . Leonardo da Vinci concurred with Aristotle's view that fossils were the remains of ancient life. For example, Leonardo noticed discrepancies with the biblical flood narrative as an explanation for fossil origins: If the Deluge had carried the shells for distances of three and four hundred miles from the sea it would have carried them mixed with various other natural objects all heaped up together; but even at such distances from
6110-591: The Song dynasty during the 11th century, who kept a specific seashell fossil with his own poem engraved on it. In his Dream Pool Essays published in 1088, Song dynasty Chinese scholar-official Shen Kuo hypothesized that marine fossils found in a geological stratum of mountains located hundreds of miles from the Pacific Ocean was evidence that a prehistoric seashore had once existed there and shifted over centuries of time . His observation of petrified bamboos in
6240-621: The Sphenisciformes (penguins) and Procellariiformes ( albatrosses and petrels ), all of the Suliformes ( gannets and cormorants ) except the darters , and some of the Charadriiformes (the gulls , skuas , terns , auks and skimmers ) are classified as seabirds. The phalaropes are usually included as well, since although they are waders ("shorebirds" in North America), two of
6370-402: The law of superposition ) preserved different assemblages of fossils, and that these assemblages succeeded one another in a regular and determinable order. He observed that rocks from distant locations could be correlated based on the fossils they contained. He termed this the principle of faunal succession . This principle became one of Darwin's chief pieces of evidence that biological evolution
6500-669: The millinery trade reached industrial levels. Muttonbirding (harvesting shearwater chicks) developed as important industries in both New Zealand and Tasmania, and the name of one species, the providence petrel , is derived from its seemingly miraculous arrival on Norfolk Island where it provided a windfall for starving European settlers. In the Falkland Islands , hundreds of thousands of penguins were harvested for their oil each year. Seabird eggs have also long been an important source of food for sailors undertaking long sea voyages, as well as being taken when settlements grow in areas near
6630-419: The razorbill (an Atlantic auk) requires 64% more energy to fly than a petrel of equivalent size. Many shearwaters are intermediate between the two, having longer wings than typical wing-propelled divers but heavier wing loadings than the other surface-feeding procellariids , leaving them capable of diving to considerable depths while still being efficient long-distance travellers. The short-tailed shearwater
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#17328521752556760-481: The shearwaters and gadfly petrels). Surface feeders in flight include some of the most acrobatic of seabirds, which either snatch morsels from the water (as do frigate-birds and some terns), or "walk", pattering and hovering on the water's surface, as some of the storm-petrels do. Many of these do not ever land in the water, and some, such as the frigatebirds, have difficulty getting airborne again should they do so. Another seabird family that does not land while feeding
6890-403: The thunderbird . There is no such direct mythological connection known from prehistoric Africa, but there is considerable evidence of tribes there excavating and moving fossils to ceremonial sites, apparently treating them with some reverence. In Japan, fossil shark teeth were associated with the mythical tengu , thought to be the razor-sharp claws of the creature, documented some time after
7020-449: The 16th century. Roman naturalist Pliny the Elder wrote of " tongue stones ", which he called glossopetra . These were fossil shark teeth, thought by some classical cultures to look like the tongues of people or snakes. He also wrote about the horns of Ammon , which are fossil ammonites , whence the group of shelled octopus-cousins ultimately draws its modern name. Pliny also makes one of
7150-739: The 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization , including permineralization , casts and molds, authigenic mineralization , replacement and recrystallization, adpression, carbonization , and bioimmuration. Fossils vary in size from one- micrometre (1 μm) bacteria to dinosaurs and trees, many meters long and weighing many tons. A fossil normally preserves only
7280-413: The 8th century AD. In medieval China, the fossil bones of ancient mammals including Homo erectus were often mistaken for " dragon bones" and used as medicine and aphrodisiacs . In addition, some of these fossil bones are collected as "art" by scholars, who left scripts on various artifacts, indicating the time they were added to a collection. One good example is the famous scholar Huang Tingjian of
7410-515: The Antarctic mainland, are unlikely to find anything to eat around their breeding sites. The marbled murrelet nests inland in old growth forest , seeking huge conifers with large branches to nest on. Other species, such as the California gull , nest and feed inland on lakes, and then move to the coasts in the winter. Some cormorant, pelican , gull and tern species have individuals that never visit
7540-625: The Arctic tern; birds that nest in New Zealand and Chile and spend the northern summer feeding in the North Pacific off Japan, Alaska and California, an annual round trip of 64,000 kilometres (40,000 mi). Other species also migrate shorter distances away from the breeding sites, their distribution at sea determined by the availability of food. If oceanic conditions are unsuitable, seabirds will emigrate to more productive areas, sometimes permanently if
7670-700: The Austral summer in Antarctica. Other species also undertake trans-equatorial trips, both from the north to the south, and from south to north. The population of elegant terns , which nest off Baja California , splits after the breeding season with some birds travelling north to the Central Coast of California and some travelling as far south as Peru and Chile to feed in the Humboldt Current . The sooty shearwater undertakes an annual migration cycle that rivals that of
7800-620: The Firth of Forth; in 2014, this colony contained some 75,000 pairs. Sulasgeir off the coast of the Isle of Lewis , St. Kilda , Grassholm in Pembrokeshire , Bempton Cliffs in the East Riding of Yorkshire , Sceilig Bheag , Ireland, Cape St. Mary's , Newfoundland, and Bonaventure Island , Quebec , are also important northern-gannet breeding sites. The three gannet species are now usually placed in
7930-597: The Preservation of Favoured Races in the Struggle for Life , the oldest animal fossils were those from the Cambrian Period, now known to be about 540 million years old. He worried about the absence of older fossils because of the implications on the validity of his theories, but he expressed hope that such fossils would be found, noting that: "only a small portion of the world is known with accuracy." Darwin also pondered
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#17328521752558060-555: The Proterozoic and deeper still in the Archean is only "recounted by microscopic fossils and subtle chemical signals." Molecular biologists, using phylogenetics , can compare protein amino acid or nucleotide sequence homology (i.e., similarity) to evaluate taxonomy and evolutionary distances among organisms, with limited statistical confidence. The study of fossils, on the other hand, can more specifically pinpoint when and in what organism
8190-543: The UK was the Scottish Seabird Centre , near the important bird sanctuaries on Bass Rock , Fidra and the surrounding islands. The area is home to huge colonies of gannets, puffins , skuas and other seabirds. The centre allows visitors to watch live video from the islands as well as learn about the threats the birds face and how we can protect them, and has helped to significantly raise the profile of seabird conservation in
8320-480: The UK. Seabird tourism can provide income for coastal communities as well as raise the profile of seabird conservation, although it needs to be managed to ensure it does not harm the colonies and nesting birds. For example, the northern royal albatross colony at Taiaroa Head in New Zealand attracts 40,000 visitors a year. The plight of albatross and large seabirds, as well as other marine creatures, being taken as bycatch by long-line fisheries, has been addressed by
8450-517: The United Kingdom, the term " gannet " is used to refer to people who steadily eat vast quantities of food, especially at public functions. Young gannets were historically used as a food source, a tradition still practised in Ness , Scotland, where they are called "guga". Like examples of continued traditional whale harvesting , the modern-day hunting of gannet chicks results in great controversies as to whether it should continue to be afforded "exemption from
8580-460: The albatrosses and gulls, are more well known to humans. The albatross has been described as "the most legendary of birds", and have a variety of myths and legends associated with them. While it is widely considered unlucky to harm them, the notion that sailors believed that is a myth that derives from Samuel Taylor Coleridge 's famous poem, " The Rime of the Ancient Mariner ", in which a sailor
8710-448: The attention of predators , principally other birds, and many species attend their colonies nocturnally to avoid predation. Birds from different colonies often forage in different areas to avoid competition. Like many birds, seabirds often migrate after the breeding season . Of these, the trip taken by the Arctic tern is the farthest of any bird, crossing the equator in order to spend
8840-413: The beach, indicating the fossils were once living animals. He had previously explained them in terms of vaporous exhalations , which Persian polymath Avicenna modified into the theory of petrifying fluids ( succus lapidificatus ). Recognition of fossil seashells as originating in the sea was built upon in the 14th century by Albert of Saxony , and accepted in some form by most naturalists by
8970-710: The beginning of recorded history. The fossils themselves are referred to as the fossil record. The fossil record was one of the early sources of data underlying the study of evolution and continues to be relevant to the history of life on Earth . Paleontologists examine the fossil record to understand the process of evolution and the way particular species have evolved. Fossils have been visible and common throughout most of natural history, and so documented human interaction with them goes back as far as recorded history, or earlier. There are many examples of paleolithic stone knives in Europe, with fossil echinoderms set precisely at
9100-454: The bird is young. After fledging, juvenile birds often disperse further than adults, and to different areas, so are commonly sighted far from a species' normal range. Some species, such as the auks, do not have a concerted migration effort, but drift southwards as the winter approaches. Other species, such as some of the storm petrels, diving petrels and cormorants, never disperse at all, staying near their breeding colonies year round. While
9230-512: The bookshop proprietor ( John Cleese ) for "the expurgated version" of Olsen's Standard Book of British Birds , "the one without the gannet", because he does not like gannets due to their "long nasty beaks". Desperate to satisfy the customer, the proprietor tears the page about the gannet out of the book, only for the customer to then refuse to buy it because it is damaged. The sketch is reprised in Monty Python's Contractual Obligation Album , where
9360-480: The chicks of the sooty shearwater as they have done for centuries, using traditional stewardship, kaitiakitanga , to manage the harvest, but now also work with the University of Otago in studying the populations. In Greenland , however, uncontrolled hunting is pushing many species into steep decline. Other human factors have led to declines and even extinctions in seabird populations and species. Of these, perhaps
9490-510: The customer ( Graham Chapman ) says he does not like the gannet because "they wet their nests." In Series 1, Episode 3 of The F Word , Gordon Ramsay travels to the northwestern coast of Scotland and is shown how to prepare, cook, and eat gannet. Seabirds Seabirds (also known as marine birds ) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution , as
9620-453: The definition of seabirds suggests that the birds in question spend their lives on the ocean, many seabird families have many species that spend some or even most of their lives inland away from the sea. Most strikingly, many species breed tens, hundreds or even thousands of miles inland. Some of these species still return to the ocean to feed; for example, the snow petrel , the nests of which have been found 480 kilometres (300 mi) inland on
9750-660: The deity Sopdu , the Morning Star, equivalent of Venus in Roman mythology. Fossils appear to have directly contributed to the mythology of many civilizations, including the ancient Greeks. Classical Greek historian Herodotos wrote of an area near Hyperborea where gryphons protected golden treasure. There was indeed gold mining in that approximate region , where beaked Protoceratops skulls were common as fossils. A later Greek scholar, Aristotle , eventually realized that fossil seashells from rocks were similar to those found on
9880-451: The disease have scarred digestive tracts from ingesting plastic waste . "When birds ingest small pieces of plastic, they found, it inflames the digestive tract. Over time, the persistent inflammation causes tissues to become scarred and disfigured, affecting digestion, growth and survival." The threats faced by seabirds have not gone unnoticed by scientists or the conservation movement . As early as 1903, U.S. President Theodore Roosevelt
10010-456: The dive to combat natural buoyancy (caused by air trapped in plumage), and thus uses less energy than the dedicated pursuit divers, allowing them to utilise more widely distributed food resources, for example, in impoverished tropical seas. In general, this is the most specialised method of hunting employed by seabirds; other non-specialists (such as gulls and skuas) may employ it but do so with less skill and from lower heights. In brown pelicans,
10140-499: The diversity of seabirds in general was much higher than today. The cause the decline in species at the end of the Pleistocene is not clear; increased competition due to the spread of marine mammals may have played a role. The genus Morus is much better documented in the fossil record than Sula , though the latter is more numerous today. The reasons are not clear; boobies possibly were better adapted or simply "lucky" to occur in
10270-466: The dry northern climate zone of what is now Yan'an , Shaanxi province, China, led him to advance early ideas of gradual climate change due to bamboo naturally growing in wetter climate areas. In medieval Christendom , fossilized sea creatures on mountainsides were seen as proof of the biblical deluge of Noah's Ark . After observing the existence of seashells in mountains, the ancient Greek philosopher Xenophanes (c. 570 – 478 BC) speculated that
10400-415: The earlier known references to toadstones , thought until the 18th century to be a magical cure for poison originating in the heads of toads, but which are fossil teeth from Lepidotes , a Cretaceous ray-finned fish. The Plains tribes of North America are thought to have similarly associated fossils, such as the many intact pterosaur fossils naturally exposed in the region, with their own mythology of
10530-413: The earliest instances known is in southern Chile, where archaeological excavations in middens has shown hunting of albatrosses, cormorants and shearwaters from 5000 BP. This pressure has led to some species becoming extinct in many places; in particular, at least 20 species of an original 29 no longer breed on Easter Island . In the 19th century, the hunting of seabirds for fat deposits and feathers for
10660-550: The earliest known stromatolites are over 3.4 billion years old. The fossil record is life's evolutionary epic that unfolded over four billion years as environmental conditions and genetic potential interacted in accordance with natural selection. The Virtual Fossil Museum Paleontology has joined with evolutionary biology to share the interdisciplinary task of outlining the tree of life, which inevitably leads backwards in time to Precambrian microscopic life when cell structure and functions evolved. Earth's deep time in
10790-460: The earth during earthquake and subsidences, and petrifies whatever comes into contact with it. As a matter of fact, the petrifaction of the bodies of plants and animals is not more extraordinary than the transformation of waters. From the 13th century to the present day, scholars pointed out that the fossil skulls of Deinotherium giganteum , found in Crete and Greece, might have been interpreted as being
10920-470: The establishment of wildlife refuges and adjustments to fishing techniques. There exists no single definition of which groups, families and species are seabirds, and most definitions are in some way arbitrary. Elizabeth Shreiber and Joanna Burger, two seabird scientists, said, "The one common characteristic that all seabirds share is that they feed in saltwater ; but, as seems to be true with any statement in biology, some do not." However, by convention all of
11050-404: The exception of the cormorants and some terns, and in common with most other birds, all seabirds have waterproof plumage . However, compared to land birds, they have far more feathers protecting their bodies. This dense plumage is better able to protect the bird from getting wet, and cold is kept out by a dense layer of down feathers . The cormorants possess a layer of unique feathers that retain
11180-478: The existence of a world previous to ours, destroyed by some kind of catastrophe. Interest in fossils, and geology more generally, expanded during the early nineteenth century. In Britain, Mary Anning 's discoveries of fossils, including the first complete ichthyosaur and a complete plesiosaurus skeleton, sparked both public and scholarly interest. Early naturalists well understood the similarities and differences of living species leading Linnaeus to develop
11310-676: The feathers resist abrasion. Seabirds evolved to exploit different food resources in the world's seas and oceans, and to a great extent, their physiology and behaviour have been shaped by their diet . These evolutionary forces have often caused species in different families and even orders to evolve similar strategies and adaptations to the same problems, leading to remarkable convergent evolution , such as that between auks and penguins. There are four basic feeding strategies, or ecological guilds, for feeding at sea: surface feeding, pursuit diving, plunge-diving, and predation of higher vertebrates ; within these guilds, there are multiple variations on
11440-466: The first time in over a hundred years. Seabird mortality caused by long-line fisheries can be greatly reduced by techniques such as setting long-line bait at night, dying the bait blue, setting the bait underwater, increasing the amount of weight on lines and by using bird scarers, and their deployment is increasingly required by many national fishing fleets. One of the Millennium Projects in
11570-478: The frequency of breeding failures due to unfavourable marine conditions, and the relative lack of predation compared to that of land-living birds. Because of the greater investment in raising the young and because foraging for food may occur far from the nest site, in all seabird species except the phalaropes, both parents participate in caring for the young, and pairs are typically at least seasonally monogamous . Many species, such as gulls, auks and penguins, retain
11700-616: The genus Morus , Abbott's booby in Papasula , and the remaining boobies in Sula . However, some authorities believe that all nine sulid species should be considered congeneric, in Sula . At one time, the various gannet species were considered to be a single species. [REDACTED] [REDACTED] [REDACTED] Most fossil gannets are from the Late Miocene or Pliocene , when
11830-519: The hand grip, dating back to Homo heidelbergensis and Neanderthals . These ancient peoples also drilled holes through the center of those round fossil shells, apparently using them as beads for necklaces. The ancient Egyptians gathered fossils of species that resembled the bones of modern species they worshipped. The god Set was associated with the hippopotamus , therefore fossilized bones of hippo-like species were kept in that deity's temples. Five-rayed fossil sea urchin shells were associated with
11960-636: The largest seabirds in the North Atlantic , having a wingspan of up to two metres ( 6 + 1 ⁄ 2 feet). The other two species occur in the temperate seas around southern Africa , southern Australia, and New Zealand. "Gannet" is derived from Old English ganot meaning "strong or masculine", ultimately from the same Old Germanic root as "gander". Morus is derived from Ancient Greek μωρός moros "stupid" or "foolish" due to lack of fear shown by breeding gannets and boobies, allowing them to be easily killed. Gannets hunt fish by diving into
12090-535: The limits of fossilization. Fossils of two enigmatic bilaterians, the worm-like Markuelia and a putative, primitive protostome , Pseudooides , provide a peek at germ layer embryonic development. These 543-million-year-old embryos support the emergence of some aspects of arthropod development earlier than previously thought in the late Proterozoic. The preserved embryos from China and Siberia underwent rapid diagenetic phosphatization resulting in exquisite preservation, including cell structures. This research
12220-468: The longest period of parental care of any bird except a few raptors and the southern ground hornbill , with each chick fledging after four to six months and continued assistance after that for up to fourteen months. Due to the extended period of care, breeding occurs every two years rather than annually for some species. This life-history strategy has probably evolved both in response to the challenges of living at sea (collecting widely scattered prey items),
12350-408: The marine ecosystems caused by dredging, which alters the biodiversity of the seafloor, can also have a negative impact. The hunting of seabirds and the collecting of seabird eggs have contributed to the declines of many species, and the extinction of several, including the great auk and the spectacled cormorant . Seabirds have been hunted for food by coastal peoples throughout history—one of
12480-569: The middle Miocene ( Langhian ). The highest diversity of seabirds apparently existed during the Late Miocene and the Pliocene . At the end of the latter, the oceanic food web had undergone a period of upheaval due to extinction of considerable numbers of marine species; subsequently, the spread of marine mammals seems to have prevented seabirds from reaching their erstwhile diversity. Seabirds have made numerous adaptations to living on and feeding in
12610-490: The most desirable nesting spaces. The tropical Bonin petrel nests during the winter to avoid competition with the more aggressive wedge-tailed shearwater . When the seasons overlap, the wedge-tailed shearwaters will kill young Bonin petrels in order to use their burrows. Many seabirds show remarkable site fidelity , returning to the same burrow, nest or site for many years, and they will defend that site from rivals with great vigour. This increases breeding success, provides
12740-552: The most serious are introduced species . Seabirds, breeding predominantly on small isolated islands, are vulnerable to predators because they have lost many behaviours associated with defence from predators. Feral cats can take seabirds as large as albatrosses, and many introduced rodents, such as the Pacific rat , take eggs hidden in burrows. Introduced goats, cattle, rabbits and other herbivores can create problems, particularly when species need vegetation to protect or shade their young. The disturbance of breeding colonies by humans
12870-428: The ocean lead to decreased availability of food and colonies are more often flooded as a consequence of sea level rise and extreme rainfall events. Heat stress from extreme temperatures is an additional threat. Some seabirds have used changing wind patterns to forage further and more efficiently. In 2023, plasticosis , a new disease caused solely by plastics, was discovered in seabirds. The birds identified as having
13000-471: The ordinary protection afforded to sea birds in UK and EU law". The Ness hunt is currently limited to 2,000 chicks per year, and dates back at least to the Iron Age. The hunt is considered to be sustainable, as between 1902 and 2003, gannet numbers in Scotland increased dramatically from 30,000 to 180,000. In "The Bookshop Sketch", originally from At Last the 1948 Show (1967), a customer ( Marty Feldman ) asks
13130-841: The other hand, most gulls are versatile and opportunistic feeders who will eat a wide variety of prey, both at sea and on land. Pursuit diving exerts greater pressures (both evolutionary and physiological) on seabirds, but the reward is a greater area in which to feed than is available to surface feeders. Underwater propulsion is provided by wings (as used by penguins, auks, diving petrels and some other species of petrel) or feet (as used by cormorants, grebes , loons and several types of fish-eating ducks ). Wing-propelled divers are generally faster than foot-propelled divers. The use of wings or feet for diving has limited their utility in other situations: loons and grebes walk with extreme difficulty (if at all), penguins cannot fly, and auks have sacrificed flight efficiency in favour of diving. For example,
13260-545: The problems involved in matching rocks of the same age across continents . Family-tree relationships also help to narrow down the date when lineages first appeared. For instance, if fossils of B or C date to X million years ago and the calculated "family tree" says A was an ancestor of B and C, then A must have evolved earlier. It is also possible to estimate how long ago two living clades diverged, in other words approximately how long ago their last common ancestor must have lived, by assuming that DNA mutations accumulate at
13390-443: The ratio of the radioactive element to its decay products shows how long ago the radioactive element was incorporated into the rock. Radioactive elements are common only in rocks with a volcanic origin, and so the only fossil-bearing rocks that can be dated radiometrically are volcanic ash layers, which may provide termini for the intervening sediments. Consequently, palaeontologists rely on stratigraphy to date fossils. Stratigraphy
13520-462: The relative ages of rock strata as determined by the early paleontologists and stratigraphers . Since the early years of the twentieth century, absolute dating methods, such as radiometric dating (including potassium/argon , argon/argon , uranium series , and, for very recent fossils, radiocarbon dating ) have been used to verify the relative ages obtained by fossils and to provide absolute ages for many fossils. Radiometric dating has shown that
13650-495: The removal of exotic invaders from increasingly large islands. Feral cats have been removed from Ascension Island , Arctic foxes from many islands in the Aleutian Islands , and rats from Campbell Island . The removal of these introduced species has led to increases in numbers of species under pressure and even the return of extirpated ones. After the removal of cats from Ascension Island, seabirds began to nest there again for
13780-480: The right places for dealing with the challenges of the Late Pliocene ecological change, or many more fossil boobies could still await discovery. Notably, gannets are today restricted to temperate oceans, while boobies are also found in tropical waters, whereas several of the prehistoric gannet species had a more equatorial distribution than their congeners of today. Fossil species of gannets are: In many parts of
13910-399: The same environmental problems and feeding niches have resulted in similar adaptations. The first seabirds evolved in the Cretaceous period , and modern seabird families emerged in the Paleogene . Seabirds generally live longer, breed later and have fewer young than other birds, but they invest a great deal of time in their young. Most species nest in colonies , varying in size from
14040-465: The same mate for several seasons, and many petrel species mate for life. Albatrosses and procellariids , which mate for life, take many years to form a pair bond before they breed, and the albatrosses have an elaborate breeding dance that is part of pair-bond formation. Ninety-five percent of seabirds are colonial, and seabird colonies are among the largest bird colonies in the world, providing one of Earth's great wildlife spectacles. Colonies of over
14170-429: The sea and that they were still living when the strait of Gibraltar was cut through. In the mountains of Parma and Piacenza multitudes of shells and corals with holes may be seen still sticking to the rocks.... In 1666, Nicholas Steno examined a shark, and made the association of its teeth with the "tongue stones" of ancient Greco-Roman mythology, concluding that those were not in fact the tongues of venomous snakes, but
14300-653: The sea at all, spending their lives on lakes, rivers, swamps and, in the case of some of the gulls, cities and agricultural land. In these cases, it is thought that these terrestrial or freshwater birds evolved from marine ancestors. Some seabirds, principally those that nest in tundra , as skuas and phalaropes do, will migrate over land as well. The more marine species, such as petrels, auks and gannets , are more restricted in their habits, but are occasionally seen inland as vagrants. This most commonly happens to young inexperienced birds, but can happen in great numbers to exhausted adults after large storms , an event known as
14430-404: The sea from a height of 30 m (100 ft) and pursuing their prey underwater, and have a number of adaptations: Gannets can achieve speeds of 100 km/h (62.13 mph) as they strike the water, enabling them to catch fish at a much greater depth than most airborne birds. The gannet's supposed capacity for eating large quantities of fish has led to "gannet" becoming a description of somebody with
14560-423: The sea we see the oysters all together and also the shellfish and the cuttlefish and all the other shells which congregate together, found all together dead; and the solitary shells are found apart from one another as we see them every day on the sea-shores. And we find oysters together in very large families, among which some may be seen with their shells still joined together, indicating that they were left there by
14690-501: The sea's edge (coast), but are also not treated as seabirds. Sea eagles and other fish-eating birds of prey are also typically excluded, however tied to marine environments they may be. German ornithologist Gerald Mayr defined the "core waterbird" clade Aequornithes in 2010. This lineage gives rise to the Gaviiformes , Sphenisciformes , Procellariiformes, Ciconiiformes , Suliformes and Pelecaniformes . The tropicbirds are part of
14820-407: The sea. Wing morphology has been shaped by the niche an individual species or family has evolved , so that looking at a wing's shape and loading can tell a scientist about its life feeding behaviour. Longer wings and low wing loading are typical of more pelagic species, while diving species have shorter wings. Species such as the wandering albatross , which forage over huge areas of sea, have
14950-416: The skewed sex ratio of western gulls in southern California. Oil spills are also a threat to seabirds: the oil is toxic, and bird feathers become saturated by the oil, causing them to lose their waterproofing. Oil pollution in particular threatens species with restricted ranges or already depressed populations. Climate change mainly affect seabirds via changes to their habitat : various processes in
15080-432: The skills of plunge-diving take several years to fully develop—once mature, they can dive from 20 m (66 ft) above the water's surface, shifting the body before impact to avoid injury. It may be that plunge divers are restricted in their hunting grounds to clear waters that afford a view of their prey from the air. While they are the dominant guild in the tropics, the link between plunge diving and water clarity
15210-581: The skulls of the Cyclopes of Greek mythology , and are possibly the origin of that Greek myth. Their skulls appear to have a single eye-hole in the front, just like their modern elephant cousins, though in fact it's actually the opening for their trunk. In Norse mythology , echinoderm shells (the round five-part button left over from a sea urchin) were associated with the god Thor , not only being incorporated in thunderstones , representations of Thor's hammer and subsequent hammer-shaped crosses as Christianity
15340-489: The spread of the northern fulmar through the United Kingdom is attributed in part to the availability of discards. Discards generally benefit surface feeders, such as gannets and petrels, to the detriment of pursuit divers like penguins and guillemots, which can get entangled in the nets. Fisheries also have negative effects on seabirds, and these effects, particularly on the long-lived and slow-breeding albatrosses, are
15470-695: The squid eaten are too large to have been caught alive, and include mid-water species likely to be beyond the reach of albatrosses. Some species will also feed on other seabirds; for example, gulls, skuas and pelicans will often take eggs, chicks and even small adult seabirds from nesting colonies, while the giant petrels can kill prey up to the size of small penguins and seal pups. Seabirds' life histories are dramatically different from those of land birds. In general, they are K-selected , live much longer (anywhere between twenty and sixty years), delay breeding for longer (for up to ten years), and invest more effort into fewer young. Most species will only have one clutch
15600-467: The sudden appearance of many groups (i.e. phyla ) in the oldest known Cambrian fossiliferous strata. Since Darwin's time, the fossil record has been extended to between 2.3 and 3.5 billion years. Most of these Precambrian fossils are microscopic bacteria or microfossils . However, macroscopic fossils are now known from the late Proterozoic. The Ediacara biota (also called Vendian biota) dating from 575 million years ago collectively constitutes
15730-451: The teeth of some long-extinct species of shark. Robert Hooke (1635–1703) included micrographs of fossils in his Micrographia and was among the first to observe fossil forams . His observations on fossils, which he stated to be the petrified remains of creatures some of which no longer existed, were published posthumously in 1705. William Smith (1769–1839) , an English canal engineer, observed that rocks of different ages (based on
15860-495: The theme. Many seabirds feed on the ocean's surface, as the action of marine currents often concentrates food such as krill , forage fish , squid , or other prey items within reach of a dipped head. Surface feeding itself can be broken up into two different approaches, surface feeding while flying (for example as practiced by gadfly petrels , frigatebirds , and storm petrels ), and surface feeding while swimming (examples of which are practiced by gulls , fulmars , many of
15990-491: The three species ( Red and Red-necked ) are oceanic for nine months of the year, crossing the equator to feed pelagically. Loons and grebes , which nest on lakes but winter at sea, are usually categorized as water birds, not seabirds. Although there are a number of sea ducks in the family Anatidae that are truly marine in the winter, by convention they are usually excluded from the seabird grouping. Many waders (or shorebirds) and herons are also highly marine, living on
16120-499: The tropicbirds and some penguins), but most of the colour in seabirds appears in the bills and legs. The plumage of seabirds is thought in many cases to be for camouflage , both defensive (the colour of US Navy battleships is the same as that of Antarctic prions , and in both cases it reduces visibility at sea) and aggressive (the white underside possessed by many seabirds helps hide them from prey below). The usually black wing tips help prevent wear, as they contain melanins that help
16250-511: The world was once inundated in a great flood that buried living creatures in drying mud. In 1027, the Persian Avicenna explained fossils' stoniness in The Book of Healing : If what is said concerning the petrifaction of animals and plants is true, the cause of this (phenomenon) is a powerful mineralizing and petrifying virtue which arises in certain stony spots, or emanates suddenly from
16380-778: The world's population. These live mainly in Scotland, including the Shetland Isles . The rest of the world's northern-gannet population nests in Canada, Ireland, the Faroe Islands , and Iceland , with small numbers in France (they are present in the Bay of Biscay ), the Channel Islands , Norway, and a single colony in Germany on Heligoland . The biggest northern-gannet colony is on Scotland's Bass Rock in
16510-584: Was 22 metres (72 ft); another study, this time on Cory's shearwaters nesting near Corsica , found that of nine out of 61 male chicks that returned to breed at their natal colony bred in the burrow they were raised in, and two actually bred with their own mother. Colonies are usually situated on islands, cliffs or headlands, which land mammals have difficulty accessing. This is thought to provide protection to seabirds, which are often very clumsy on land. Coloniality often arises in types of bird that do not defend feeding territories (such as swifts , which have
16640-458: Was adopted, but also kept in houses to garner Thor's protection. These grew into the shepherd's crowns of English folklore, used for decoration and as good luck charms, placed by the doorway of homes and churches. In Suffolk , a different species was used as a good-luck charm by bakers, who referred to them as fairy loaves , associating them with the similarly shaped loaves of bread they baked. More scientific views of fossils emerged during
16770-653: Was convinced of the need to declare Pelican Island in Florida a National Wildlife Refuge to protect the bird colonies (including the nesting brown pelicans ), and in 1909 he protected the Farallon Islands. Today many important seabird colonies are given some measure of protection, from Heron Island in Australia to Triangle Island in British Columbia. Island restoration techniques, pioneered by New Zealand, enable
16900-408: Was real. Georges Cuvier came to believe that most if not all the animal fossils he examined were remains of extinct species. This led Cuvier to become an active proponent of the geological school of thought called catastrophism . Near the end of his 1796 paper on living and fossil elephants he said: All of these facts, consistent among themselves, and not opposed by any report, seem to me to prove
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