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Ornithology

Ornithology

Overview
Ornithology is a branch of zoology
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

 that concerns the study of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds. Most marked among these is the extent of studies undertaken by amateurs working within the parameters of strict scientific methodology.

The science of ornithology has a long history and studies on birds have helped develop several key concepts in evolution, behaviour and ecology such as the definition of species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, the process of speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

, instinct
Instinct
Instinct or innate behavior is the inherent inclination of a living organism toward a particular behavior.The simplest example of an instinctive behavior is a fixed action pattern, in which a very short to medium length sequence of actions, without variation, are carried out in response to a...

, learning
Learning
Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...

, ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

s, guilds
Guild (ecology)
A guild is any group of species that exploit the same resources, often in related ways. As can be seen from the list of examples below, it does not follow that the species within a guild occupy the same, or even similar, ecological niches...

, island biogeography
Island biogeography
Island biogeography is a field within biogeography that attempts to establish and explain the factors that affect the species richness of natural communities. The theory was developed to explain species richness of actual islands...

, phylogeography
Phylogeography
Phylogeography is the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals. This is accomplished by considering the geographic distribution of individuals in light of the patterns associated with a gene genealogy.This term was...

 and conservation
Bird conservation
Bird conservation is a field in the science of conservation biology related to threatened birds. Humans have had a profound effect on many bird species...

.
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Encyclopedia
Ornithology is a branch of zoology
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

 that concerns the study of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds. Most marked among these is the extent of studies undertaken by amateurs working within the parameters of strict scientific methodology.

The science of ornithology has a long history and studies on birds have helped develop several key concepts in evolution, behaviour and ecology such as the definition of species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, the process of speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

, instinct
Instinct
Instinct or innate behavior is the inherent inclination of a living organism toward a particular behavior.The simplest example of an instinctive behavior is a fixed action pattern, in which a very short to medium length sequence of actions, without variation, are carried out in response to a...

, learning
Learning
Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...

, ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

s, guilds
Guild (ecology)
A guild is any group of species that exploit the same resources, often in related ways. As can be seen from the list of examples below, it does not follow that the species within a guild occupy the same, or even similar, ecological niches...

, island biogeography
Island biogeography
Island biogeography is a field within biogeography that attempts to establish and explain the factors that affect the species richness of natural communities. The theory was developed to explain species richness of actual islands...

, phylogeography
Phylogeography
Phylogeography is the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals. This is accomplished by considering the geographic distribution of individuals in light of the patterns associated with a gene genealogy.This term was...

 and conservation
Bird conservation
Bird conservation is a field in the science of conservation biology related to threatened birds. Humans have had a profound effect on many bird species...

. While early ornithology was principally concerned with descriptions and distributions of species, ornithologists today seek answers to very specific questions, often using birds as models to test hypotheses or predictions based on theories. Most modern biological theories apply across taxonomic groups and the number of professional scientists who identify themselves as "ornithologists" has therefore declined. A wide range of tools and techniques are used in ornithology and innovations are constantly made.

History


The history of ornithology largely reflects the trends in the history of biology
History of biology
The history of biology traces the study of the living world from ancient to modern times. Although the concept of biology as a single coherent field arose in the 19th century, the biological sciences emerged from traditions of medicine and natural history reaching back to ayurveda, ancient Egyptian...

. Trends include the move from mere descriptions to the identification of patterns and then towards elucidating the processes that produce the patterns.

Early knowledge and study



Humans must have observed birds from the earliest times, and stone age
Stone Age
The Stone Age is a broad prehistoric period, lasting about 2.5 million years , during which humans and their predecessor species in the genus Homo, as well as the earlier partly contemporary genera Australopithecus and Paranthropus, widely used exclusively stone as their hard material in the...

 drawings are among the oldest indications of an interest in birds. Birds were perhaps important as a food source, and bones of as many as 80 species have been found in excavations of early Stone Age
Stone Age
The Stone Age is a broad prehistoric period, lasting about 2.5 million years , during which humans and their predecessor species in the genus Homo, as well as the earlier partly contemporary genera Australopithecus and Paranthropus, widely used exclusively stone as their hard material in the...

 settlements.

Cultures around the world have rich vocabularies related to birds. Traditional bird names are often based on detailed knowledge of the behaviour, with many names being onomatopoeic, many still in use. Traditional knowledge may also involve the use of birds in folk medicine and knowledge of these practices are passed on through oral traditions (see ethno-ornithology
Ethnoornithology
Ethnoornithology is the study of the relationship between people and birds . It is a branch of ethnozoology and so of the wider field of ethnobiology...

). Hunting of wild birds as well as their domestication would have required considerable knowledge of their habits. Poultry
Poultry
Poultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...

 farming and falconry
Falconry
Falconry is "the taking of wild quarry in its natural state and habitat by means of a trained raptor". There are two traditional terms used to describe a person involved in falconry: a falconer flies a falcon; an austringer flies a hawk or an eagle...

 were practised from early times in many parts of the world. Artificial incubation of poultry was practised in China around 246 BC and around at least 400 BC in Egypt. The Egyptians also made use of birds in their hieroglyphic scripts, many of which, though stylized, are still identifiable to species.

Early written records provide valuable information on the past distributions of species. For instance Xenophon
Xenophon
Xenophon , son of Gryllus, of the deme Erchia of Athens, also known as Xenophon of Athens, was a Greek historian, soldier, mercenary, philosopher and a contemporary and admirer of Socrates...

 records the abundance of the Ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...

 in Assyria
Assyria
Assyria was a Semitic Akkadian kingdom, extant as a nation state from the mid–23rd century BC to 608 BC centred on the Upper Tigris river, in northern Mesopotamia , that came to rule regional empires a number of times through history. It was named for its original capital, the ancient city of Assur...

 (Anabasis, i. 5); this subspecies from Asia minor is extinct and all extant Ostrich races are today restricted to Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

. Other old writings such as the Vedas
Vedas
The Vedas are a large body of texts originating in ancient India. Composed in Vedic Sanskrit, the texts constitute the oldest layer of Sanskrit literature and the oldest scriptures of Hinduism....

(1500-800 BC) demonstrate the careful observation of avian life histories and includes the earliest reference to the habit of brood parasitism
Brood parasite
Brood parasites are organisms that use the strategy of brood parasitism, a kind of kleptoparasitism found among birds, fish or insects, involving the manipulation and use of host individuals either of the same or different species to raise the young of the brood-parasite...

 by the Asian Koel
Asian Koel
The Asian Koel is a member of the cuckoo order of birds, the Cuculiformes. It is found in South Asia, China, and Southeast Asia. It forms a superspecies with the closely related Black-billed and Pacific Koels which are sometimes treated as subspecies...

 (Eudynamys scolopacea). Like writing, the early art of China, Japan, Persia and India also demonstrate knowledge, with examples of scientifically accurate bird illustrations.

Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

 in 350 BC in his Historia Animalium noted the habit of bird migration
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, moulting, egg laying and life spans. He however introduced and propagated several myths, such as the idea that swallow
Swallow
The swallows and martins are a group of passerine birds in the family Hirundinidae which are characterised by their adaptation to aerial feeding...

s hibernated in winter although he noted that cranes
Common Crane
The Common Crane , also known as the Eurasian Crane, is a bird of the family Gruidae, the cranes.It is a large, stately bird and a medium-sized crane at 100–130 cm long, with a 180–240 cm wingspan and a weight of 4.5–6 kg...

 migrated from the steppes of Scythia
Scythia
In antiquity, Scythian or Scyths were terms used by the Greeks to refer to certain Iranian groups of horse-riding nomadic pastoralists who dwelt on the Pontic-Caspian steppe...

 to the marshes at the headwaters of the Nile
Nile
The Nile is a major north-flowing river in North Africa, generally regarded as the longest river in the world. It is long. It runs through the ten countries of Sudan, South Sudan, Burundi, Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Ethiopia, Uganda and Egypt.The Nile has two major...

. The idea of swallow hibernation became so well established that, even as late as in 1878, Elliott Coues
Elliott Coues
Elliott Coues was an American army surgeon, historian, ornithologist and author.Coues was born in Portsmouth, New Hampshire. He graduated at Columbian University, Washington, D.C., in 1861, and at the Medical school of that institution in 1863...

 could list as many as 182 contemporary publications dealing with the hibernation of swallows and little published evidence to contradict the theory. Similar misconceptions existed regarding the breeding of Barnacle geese. Their nests had not been seen and it was believed that they grew by transformations of goose barnacles, an idea that became prevalent from around the 11th century and noted by Bishop Giraldus Cambrensis (Gerald of Wales) in Topographia Hiberniae (1187).

The origins of falconry have been traced to Mesopotamia
Mesopotamia
Mesopotamia is a toponym for the area of the Tigris–Euphrates river system, largely corresponding to modern-day Iraq, northeastern Syria, southeastern Turkey and southwestern Iran.Widely considered to be the cradle of civilization, Bronze Age Mesopotamia included Sumer and the...

 and the earliest record comes from the reign of Sargon II (722–705 BC). Falconry made its entry to Europe only after AD 400, brought in from the East after invasions by the Huns and Allans. Frederick II
Frederick II, Holy Roman Emperor
Frederick II , was one of the most powerful Holy Roman Emperors of the Middle Ages and head of the House of Hohenstaufen. His political and cultural ambitions, based in Sicily and stretching through Italy to Germany, and even to Jerusalem, were enormous...

 of Hohenstaufen (1194–1250) learnt about Arabian falconry during wars in the region and obtained an Arabic treatise on falconry by Moamyn. He had this work translated into Latin and also conducted experiments on birds in his menagerie
Menagerie
A menagerie is/was a form of keeping common and exotic animals in captivity that preceded the modern zoological garden. The term was first used in seventeenth century France in reference to the management of household or domestic stock. Later, it came to be used primarily in reference to...

. By sealing the eyes of vultures and placing food nearby, he concluded that they found food by sight, and not by smell. He also developed methods to keep and train falcons. The studies that he undertook over nearly 30 years, were published in 1240 as De Arte Venandi cum Avibus
De arte venandi cum avibus
De Arte Venandi cum Avibus, literally "The Art of Hunting with Birds", is a Latin treatise on ornithology and Falconry written in the 1240s by Frederick II, and dedicated to his son Manfred....

 (The Art of Hunting with Birds), considered one of the earliest studies on bird behaviour.

Several early German and French scholars compiled old works and conducted new research on birds. These included Guillaume Rondelet
Guillaume Rondelet
Guillaume Rondelet , known also as Rondeletus , was Regus Professor of medicine at the University of Montpellier in southern France and Chancellor of the University between 1556 and his death in 1566. He achieved renown as an anatomist and a naturalist with a particular interest in botany and zoology...

 who described his observations in the Mediterranean and Pierre Belon
Pierre Belon
Pierre Belon was a French naturalist. He is sometimes known as Pierre Belon du Mans, or, in Latin translations of his works, as Petrus Bellonius Cenomanus.Belon was born in 1517 at Soulletiere near Cérans-Foulletourte...

 who described the fish and birds that he had seen in France and the Levant. Belon's Book of Birds (1555) is a folio volume with descriptions of some two hundred species. His comparison of the skeleton of humans and birds is considered as a landmark in comparative anatomy
Comparative anatomy
Comparative anatomy is the study of similarities and differences in the anatomy of organisms. It is closely related to evolutionary biology and phylogeny .-Description:...

. Volcher Coiter
Volcher Coiter
Volcher Coiter was a Dutch anatomist who established the study of comparative osteology and first described cerebrospinal meningitis.Coiter was born in Groningen...

 (1534–1576), a Dutch anatomist made detailed studies of the internal structures of birds and produced a classification of birds, De Diferentiis Avium (around 1572), that was based on structure and habits. Konrad Gesner wrote the Vogelbuch and Icones avium omnium around 1557. Like Gesner, Ulisse Aldrovandi
Ulisse Aldrovandi
Ulisse Aldrovandi was an Italian naturalist, the moving force behind Bologna's botanical garden, one of the first in Europe. Carolus Linnaeus and the comte de Buffon reckoned him the father of natural history studies...

, an encyclopedic naturalist began a 14-volume natural history with three volumes on birds, entitled ornithologiae hoc est de avibus historiae libri XII which was published from 1599 to 1603. Aldrovandi showed great interest in plants and animals and his work included 3000 drawings of fruits, flowers, plants and animals, published in 363 volumes. His Ornithology alone covers 2000 pages and included such aspects as the chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...

 and poultry techniques. William Turner's Historia Avium ("History of Birds"), published at Cologne
Cologne
Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...

 in 1544, was an early ornithological work from England. He noted the commonness of kite
Red Kite
The Red Kite is a medium-large bird of prey in the family Accipitridae, which also includes many other diurnal raptors such as eagles, buzzards, and harriers. The species is currently endemic to the Western Palearctic region in Europe and northwest Africa, though formerly also occurred just...

 in English cities where they snatched food out of the hands of children. He included folk beliefs such as those of anglers. Anglers believed that the Osprey
Osprey
The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...

 emptied their fishponds and would kill them, mixing the flesh of the Osprey into their fish bait. Turner's work reflected the violent times that he lived in and stands in contrast to later works such as Gilbert White
Gilbert White
Gilbert White FRS was a pioneering English naturalist and ornithologist.-Life:White was born in his grandfather's vicarage at Selborne in Hampshire. He was educated at the Holy Ghost School and by a private tutor in Basingstoke before going to Oriel College, Oxford...

's The Natural History and Antiquities of Selborne
The Natural History and Antiquities of Selborne
The Natural History and Antiquities of Selborne, or just The Natural History of Selborne is a book by pioneering English naturalist and ornithologist Gilbert White first published in 1789...

that were written in a tranquil era.

In the 17th century Francis Willughby
Francis Willughby
thumbnail|200px|right|A page from the Ornithologia, showing [[Jackdaw]], [[Chough]], [[European Magpie|Magpie]] and [[Eurasian Jay|Jay]], all [[Corvidae|crows]]....

 (1635–1672) and John Ray
John Ray
John Ray was an English naturalist, sometimes referred to as the father of English natural history. Until 1670, he wrote his name as John Wray. From then on, he used 'Ray', after "having ascertained that such had been the practice of his family before him".He published important works on botany,...

 (1627–1705) came up with the first major system of bird classification that was based on function and morphology rather than on form or behaviour. Willughby's Ornithologiae libri tres (1676) completed by John Ray is sometimes considered to mark the beginning of scientific ornithology. Ray also worked on Ornithologia which was published posthumously in 1713 as Synopsis methodica avium et piscium. The earliest list of British birds, Pinax Rerum Naturalium Britannicarum was written by Christopher Merrett
Christopher Merrett
Christopher Merret FRS was an English physician and scientist. He was the first to document the deliberate addition of sugar for the production of sparkling wine, and produced the first list of British birds.-Life:Merret was born in Winchcombe, Gloucestershire on 16 February; Hunter gives the...

 in 1667, however it was not considered of value by many including John Ray.

Towards the late 18th century, Mathurin Jacques Brisson
Mathurin Jacques Brisson
Mathurin Jacques Brisson was a French zoologist and natural philosopher.Brisson was born at Fontenay-le-Comte. The earlier part of his life was spent in the pursuit of natural history, his published works in this department including Le Règne animal and Ornithologie...

 (1723–1806) and Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, cosmologist, and encyclopedic author.His works influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Georges Cuvier...

 (1707–1788) began new works on birds. Brisson produced a six-volume work Ornithologie in 1760 and Buffon's included nine volumes (volumes 16-24) on birds Histoire naturelle des oiseaux (1770–1785) in his work on science Histoire naturelle générale et particulière (1749–1804). Coenraad Jacob Temminck
Coenraad Jacob Temminck
Coenraad Jacob Temminck was a Dutch aristocrat and zoologist.Temminck was the first director of the National Natural History Museum at Leiden from 1820 until his death. His Manuel d'ornithologie, ou Tableau systematique des oiseaux qui se trouvent en Europe was the standard work on European birds...

 (1778–1858) sponsored François Le Vaillant
François Le Vaillant
François Levaillant or Le Vaillant was a French author, explorer, naturalist, zoological collector, and noted ornithologist.-Biography:...

 [1753-1824] to collect bird specimens in Africa and this resulted in Le Vaillant's six-volume Histoire naturelle des oiseaux d'Afrique (1796–1808). Louis Jean Pierre Vieillot
Louis Jean Pierre Vieillot
Louis Jean Pierre Vieillot was a French ornithologist.Vieillot described a large number of birds for the first time, especially those he encountered during the time he spent in the West Indies and North America, and 26 genera established by him are still in use...

 (1748–1831) spent ten years studying North American birds and wrote the Histoire naturelle des oiseaux de l'Amerique septentrionale (1807-1808?). Vieillot pioneered in the use of life-histories and habits in classification.

Scientific studies



It was not until the Victorian era—with the emergence of the gun, the concept of natural history, and the collection of natural objects such as bird eggs and skins—that ornithology emerged as a specialized science. This specialization led to the formation in Britain of the British Ornithologists' Union
British Ornithologists' Union
The British Ornithologists' Union aims to encourage the study of birds in Britain, Europe and elsewhere, in order to understand their biology and to aid their conservation....

 in 1858. In 1859 the members founded its journal The Ibis. The sudden spurt in ornithology was also due in part to colonialization
Colonialism
Colonialism is the establishment, maintenance, acquisition and expansion of colonies in one territory by people from another territory. It is a process whereby the metropole claims sovereignty over the colony and the social structure, government, and economics of the colony are changed by...

. A hundred years later, in 1959, R. E. Moreau
Reginald Ernest Moreau
Reginald Ernest Moreau, , was an English ornithologist.Moreau was among the pioneering ornithologists who focused on life history studies of birds. In 1944 he suggested in a paper in the Ibis that birds laid larger clutches of eggs in the higher latitudes than in the tropics. This was based on his...

 noted that ornithology in this period was preoccupied with the geographical distributions of various species of birds.
The bird collectors of the Victorian era observed the variations in bird forms and habits across geographic regions, noting local specialization and variation in widespread species. The collections of museums and private collectors grew with contributions from various parts of the world. The naming of species with binomials and the organization of birds into groups based on their similarities became the main work of museum specialists. The variations in widespread birds across geographical region caused the introduction of trinomial names.

The search for patterns in the variations of birds was attempted by many. Early ornithologists like William Swainson followed the Quinarian system
Quinarian system
The Quinarian system was a method of zoological classification which had a brief period of popularity in the mid 19th century, especially among British naturalists. It was largely developed by the entomologist W. S. MacLeay in 1819. The system was followed by Nicholas Aylward Vigors and William...

 and this was replaced by more complex "maps" of affinities in works by Hugh Edwin Strickland
Hugh Edwin Strickland
Hugh Edwin Strickland , was an English geologist, ornithologist,naturalist, and systematist.Strickland was born at Reighton, in the East Riding of Yorkshire. He was the second son of Henry Eustatius Strickland of Apperley, Gloucestershire, by his wife Mary, daughter of Edmund Cartwright, D.D. [q...

 and Alfred Russell Wallace.

The Galapagos finch
Finch
The true finches are passerine birds in the family Fringillidae. They are predominantly seed-eating songbirds. Most are native to the Northern Hemisphere, but one subfamily is endemic to the Neotropics, one to the Hawaiian Islands, and one subfamily – monotypic at genus level – is found...

es were especially influential in the development of Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

's theory of evolution. His contemporary Alfred Russel Wallace
Alfred Russel Wallace
Alfred Russel Wallace, OM, FRS was a British naturalist, explorer, geographer, anthropologist and biologist...

 also noted these variations and the geographical separations between different forms leading to the study of biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...

. Wallace was influenced by the work of Philip Lutley Sclater on the distribution patterns of birds.

For Darwin, the problem was how species arose from a common ancestor, but he did not attempt to find rules for delineation of species. The species problem
Species problem
The species problem or species concept is a mixture of difficult, related questions that often come up when biologists identify species and when they define the word "species"....

 was tackled by the ornithologist Ernst Mayr
Ernst Mayr
Ernst Walter Mayr was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, historian of science, and naturalist...

. Mayr was able to demonstrate that geographical isolation and the accumulation of genetic differences led to the splitting of species.

Early ornithologists were preoccupied with matters of species identification. Only systematics counted as true science and field studies were considered inferior through much of the 19th century. In 1901 Robert Ridgway wrote in the introduction to The Birds of North and Middle America that:

This early idea that the study of living birds was merely recreation held sway until ecological theories became the predominant focus of ornithological studies. The study of birds in their habitats was particularly advanced in Germany with bird ringing
Bird ringing
Bird ringing or bird banding is a technique used in the study of wild birds, by attaching a small, individually numbered, metal or plastic tag to their legs or wings, so that various aspects of the bird's life can be studied by the ability to re-find the same individual later...

 stations established as early as 1903. By the 1920s the Journal für Ornithologie included many papers on the behaviour, ecology, anatomy and physiology, many written by Erwin Stresemann
Erwin Stresemann
Erwin Stresemann was a German naturalist and ornithologist.Stresemann was one of the outstanding ornithologists of the 20th century...

. Stresemann changed the editorial policy of the journal, leading both to a unification of field and laboratory studies and a shift of research from museums to universities. Ornithology in the United States continued to be dominated by museum studies of morphological variations, species identities and geographic distributions, until it was influenced by Stresemann's student Ernst Mayr. In Britain, some of the earliest ornithological works that used the word ecology appeared in 1915. The Ibis however resisted the introduction of these new methods of study and it was not until 1943 that any paper on ecology appeared. The work of David Lack
David Lack
David Lambert Lack FRS, was a British evolutionary biologist who made contributions to ornithology, ecology and ethology. His book on the finches of the Galapagos Islands was a landmark work.- Early life :...

 on population ecology was pioneering. Newer quantitative approaches were introduced for the study of ecology and behaviour and this was not readily accepted. For instance, Claud Ticehurst wrote:

David Lack's studies on population ecology sought to find the processes involved in the regulation of population based on the evolution of optimal clutch sizes. He concluded that population was regulated primarily by density-dependent controls, and also suggested that natural selection produces life-history traits that maximize the fitness of individuals. Others like Wynne-Edwards interpreted population regulation as a mechanism that aided the "species" rather than individuals
Group selection
In evolutionary biology, group selection refers to the idea that alleles can become fixed or spread in a population because of the benefits they bestow on groups, regardless of the alleles' effect on the fitness of individuals within that group....

. This led to widespread and sometimes bitter debate on what constituted the "unit of selection". Lack also pioneered the use of many new tools for ornithological research, including the idea of using radar to study bird migration.

Birds were also widely used in studies of the niche hypothesis and Georgii Gause's competitive exclusion principle. Work on resource partitioning and the structuring of bird communities through competition were made by Robert MacArthur
Robert MacArthur
Robert Helmer MacArthur was an American ecologist who made a major impact on many areas of community and population ecology....

. Patterns of biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

 also became a topic of interest. Work on the relationship of the number of species to area and its application in the study of island biogeography
Island biogeography
Island biogeography is a field within biogeography that attempts to establish and explain the factors that affect the species richness of natural communities. The theory was developed to explain species richness of actual islands...

 was pioneered by E. O. Wilson
E. O. Wilson
Edward Osborne Wilson is an American biologist, researcher , theorist , naturalist and author. His biological specialty is myrmecology, the study of ants....

 and Robert MacArthur
Robert MacArthur
Robert Helmer MacArthur was an American ecologist who made a major impact on many areas of community and population ecology....

. These studies led to the development of the discipline of landscape ecology
Landscape ecology
Landscape ecology is the science of studying and improving relationships between urban development and ecological processes in the environment and particular ecosystems...

.

John Hurrell Crook
John Crook
John Hurrell Crook, BSc, PhD, DSc , was a British ethologist who filled a pivotal role in British primatology....

 studied the behaviour of weaverbirds and demonstrated the links between ecological conditions, behaviour and social systems. Principles from economics were introduced to the study of biology by Jerram L. Brown. This led to the study of behaviour using cost-benefit analyses. The rising interest in sociobiology
Sociobiology
Sociobiology is a field of scientific study which is based on the assumption that social behavior has resulted from evolution and attempts to explain and examine social behavior within that context. Often considered a branch of biology and sociology, it also draws from ethology, anthropology,...

 also led to a spurt of bird studies in this area.

The study of imprinting behaviour in ducks and geese by Konrad Lorenz
Konrad Lorenz
Konrad Zacharias Lorenz was an Austrian zoologist, ethologist, and ornithologist. He shared the 1973 Nobel Prize with Nikolaas Tinbergen and Karl von Frisch...

 and the studies of instinct in Herring Gulls by Nicolaas Tinbergen, led to the establishment of the field of ethology
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....

. The study of learning became an area of interest and the study of bird song
Bird song
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs are distinguished by function from calls.-Definition:The distinction between songs and calls is based upon...

 has been a model for studies in neuro-ethology. The role of hormones and physiology in the control of behaviour has also been aided by bird models. These have helped in the study of circadian and seasonal cycles. Studies on migration have attempted to answer questions on the evolution of migration, orientation and navigation.

The growth of genetics and the rise of molecular biology led to the application of the gene-centered view of evolution
Gene-centered view of evolution
The gene-centered view of evolution, gene selection theory or selfish gene theory holds that evolution occurs through the differential survival of competing genes, increasing the frequency of those alleles whose phenotypic effects successfully promote their own propagation, with gene defined as...

 to explain avian phenomena. Studies on kinship and altruism, such as helpers
Helpers at the nest
Helpers at the nest is a term used in behavioural ecology and evolutionary biology to describe a social structure in which juveniles and sexually mature adolescents of either one or both sexes, remain in association with their parents and help them raise subsequent broods or litters, instead of...

, became of particular interest. The idea of inclusive fitness
Inclusive fitness
In evolutionary biology and evolutionary psychology, the inclusive fitness of an organism is the sum of its classical fitness and the number of equivalents of its own offspring it can add to the population by supporting others...

 was used to interpret observations on behaviour and life-history and birds were widely used models for testing hypotheses based on theories postulated by W. D. Hamilton
W. D. Hamilton
William Donald Hamilton FRS was a British evolutionary biologist, widely recognised as one of the greatest evolutionary theorists of the 20th century....

 and others.

The new tools of molecular-biology changed the study of bird systematics. Systematics changed from being based on phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...

 to the underlying genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...

. The use of techniques such as DNA-DNA hybridization to study evolutionary relationships was pioneered by Charles Sibley
Charles Sibley
Charles Gald Sibley was an American ornithologist and molecular biologist. He had an immense influence on the scientific classification of birds, and the work that Sibley initiated has substantially altered our understanding of the evolutionary history of modern birds.Sibley's taxonomy has been a...

 and Jon Edward Ahlquist
Jon Edward Ahlquist
Jon Edward Ahlquist is an American molecular biologist and ornithologist who has specialized in molecular phylogenetics. He has collaborated extensively with Charles Sibley, primarily at Yale University.By 1987, both Ahlquist and Sibley had left Yale....

 resulting in what is called the Sibley-Ahlquist taxonomy
Sibley-Ahlquist taxonomy
The Sibley-Ahlquist taxonomy is a bird taxonomy proposed by Charles Sibley and Jon Edward Ahlquist. It is based on DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s....

. These early techniques have been replaced by newer ones based on mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...

 sequences and molecular phylogenetics approaches that make use of computational procedures for sequence alignment
Sequence alignment
In bioinformatics, a sequence alignment is a way of arranging the sequences of DNA, RNA, or protein to identify regions of similarity that may be a consequence of functional, structural, or evolutionary relationships between the sequences. Aligned sequences of nucleotide or amino acid residues are...

, construction of phylogenetic tree
Phylogenetic tree
A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...

s and calibration of molecular clock
Molecular clock
The molecular clock is a technique in molecular evolution that uses fossil constraints and rates of molecular change to deduce the time in geologic history when two species or other taxa diverged. It is used to estimate the time of occurrence of events called speciation or radiation...

s to infer evolutionary relationships. Molecular techniques are also widely used in studies of avian population biology
Population biology
Population biology is a study of populations of organisms, especially the regulation of population size, life history traits such as clutch size, and extinction...

 and ecology.

Rise to popularity


The use of field glasses or telescopes for bird observation began in the 1820s and 1830s with pioneers like J. Dovaston
John Freeman Milward Dovaston
John Freeman Milward Dovaston was a British poet and naturalist.Dovaston was born in West Felton in the Shrewsbury district in an estate called "The Nursery" that was started by his father John Dovaston . Dovaston Sr...

 (who also pioneered in the use of bird-feeders), but it was not until the 1880s that instruction manuals began to insist on the use of optical aids such as "a first-class telescope" or "field glass."

The rise of field guides for the identification of birds was another major innovation. The early guides were large and cumbersome and were mainly focused on identifying specimens in the hand. The earliest of the new generation of field guides was prepared by Florence Merriam
Florence Augusta Merriam Bailey
Florence Augusta Merriam Bailey was an American ornithologist and nature writer. She was born in Locust Grove, New York. The third child in her family, she was the younger sister of Clinton Hart Merriam.-Life and work:...

, sister of Clinton Hart Merriam
Clinton Hart Merriam
Clinton Hart Merriam was an American zoologist, ornithologist, entomologist and ethnographer.Known as "Hart" to his friends, Dr. Clinton Hart Merriam was born in New York City in 1855. His father, Clinton Levi Merriam, was a U.S. congressman. He studied biology and anatomy at Yale University and...

, the mammalogist. This was published in 1887 in a series Hints to Audubon Workers:Fifty Birds and How to Know Them in Grinnell's Audubon Magazine. These were followed by new field guides including classics by Roger Tory Peterson
Roger Tory Peterson
Roger Tory Peterson , was an American naturalist, ornithologist, artist, and educator, and held to be one of the founding inspirations for the 20th century environmental movement.-Background:...

.

The interest in birdwatching
Birdwatching
Birdwatching or birding is the observation of birds as a recreational activity. It can be done with the naked eye, through a visual enhancement device like binoculars and telescopes, or by listening for bird sounds. Birding often involves a significant auditory component, as many bird species are...

 grew in popularity in many parts of the world and it was realized that there was a possibility for amateurs to contribute to the professional biology. As early as 1916, Julian Huxley
Julian Huxley
Sir Julian Sorell Huxley FRS was an English evolutionary biologist, humanist and internationalist. He was a proponent of natural selection, and a leading figure in the mid-twentieth century evolutionary synthesis...

 wrote a two part article in the Auk, noting the tensions between amateurs and professionals and suggesting the possibility that the "vast army of bird-lovers and bird-watchers could begin providing the data scientists needed to address the fundamental problems of biology."

Organizations were started in many countries and these grew rapidly in membership, most notable among them being the Royal Society for the Protection of Birds
Royal Society for the Protection of Birds
Bird Notes and News was first published in April 1903.The title changed to 'Bird Notes' in 1947. In the 1950s, there were four copies per year . Each volume covered two years, spread over three calendar years...

 (RSPB) in Britain and the Audubon Society in the US. The Audubon Society started in 1885. Both these organizations were started with the primary objective of conservation. The RSPB, born in 1889, grew from a small group of women in Croydon
Croydon
Croydon is a town in South London, England, located within the London Borough of Croydon to which it gives its name. It is situated south of Charing Cross...

 who met regularly and called themselves the Fur, Fin and Feather Folk and who took a pledge "to refrain from wearing the feathers of any birds not killed for the purpose of food, the Ostrich only exempted." The organization did not allow men as members initially, avenging a policy of the British Ornithologists' Union to keep out women. Unlike the RSPB, which was primarily conservation oriented, the British Trust for Ornithology (BTO) was started in 1933 with the aim of advancing ornithological research. Members were often involved in collaborative ornithological projects. These projects have resulted in atlases which detail the distribution of bird species across Britain. In the United States, the Breeding Bird Surveys, conducted by the US Geological Survey have also produced atlases with information on breeding densities and changes in the density and distribution over time. Other volunteer collaborative ornithology projects were subsequently established in other parts of the world.

Techniques


The tools and techniques of ornithology are varied and new inventions and approaches are quickly incorporated. The techniques may be broadly dealt under the categories of those that are applicable to specimens and those that are used in the field, however the classification is rough and many analysis techniques are usable both in the laboratory and field or may require a combination of field and laboratory techniques.

Collections




The earliest approaches to modern bird study involved the collection of eggs, a practice known as oology
Oology
Oology is a branch of ornithology studying bird eggs, nests and breeding behavior. Oology can also refer to the hobby of collecting wild birds' eggs, sometimes called birdnesting or egging, which is now illegal in many jurisdictions.-As a science:Oology became increasingly popular in Britain and...

. While collecting became a pastime for many amateurs, the labels associated with these early egg collections made them unreliable for the serious study of bird breeding. In order to preserve eggs, a tiny hole was pierced and the contents extracted. This technique became standard with the invention of the blow drill around 1830. Egg collection is no longer popular; however historic museum collections have been of value in determining the effects of pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

s such as DDT
DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....

 on physiology. Museum bird collections
Bird collections
Bird collections are curated repositories of scientific specimens consisting of birds and their parts. They are a research resource for ornithology, the science of birds, and for other scientific disciplines in which information about birds is useful...

 continue to act as a resource for taxonomic studies.

The use of bird skins to document species has been a standard part of systematic ornithology. Bird skins are prepared by retaining the key bones of the wings, leg and skull along with the skin and feathers. In the past, they were treated with arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

 to prevent fungal and insect (mostly dermestid) attack. Arsenic, being toxic, was replaced by borax
Borax
Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...

. Amateur and professional collectors became familiar with these skinning techniques and started sending in their skins to museums, some of them from distant locations. This led to the formation of huge collections of bird skins in museums in Europe and North America. Many private collections were also formed. These became references for comparison of species and the ornithologists at these museums were able to compare species from different locations, often places that they themselves never visited. Morphometrics
Morphometrics
Morphometrics refers to the quantitative analysis of form, a concept that encompasses size and shape. Morphometric analyses are commonly performed on organisms, and are useful in analyzing their fossil record, the impact of mutations on shape, developmental changes in form, covariances between...

 of these skins, particularly the lengths of the tarsus, bill, tail and wing became important in the descriptions of bird species. These skin collections have been utilized in more recent times for studies on molecular phylogenetics by the extraction of ancient DNA
Ancient DNA
Ancient DNA is DNA isolated from ancient specimens. It can be also loosely described as any DNA recovered from biological samples that have not been preserved specifically for later DNA analyses...

. The importance of type specimens
Biological type
In biology, a type is one particular specimen of an organism to which the scientific name of that organism is formally attached...

 in the description of species make skin collections a vital resource for systematic ornithology. However, with the rise of molecular techniques, it has now become possible to establish the taxonomic status of new discoveries, such as the Bulo Burti Boubou
Bulo Burti Boubou
The Somali Boubou is a medium-size bushshrike. It was split from the Tropical Boubou as a result of DNA sequence analysis, and this change in status was recognized by the International Ornithological Committee in 2008...

 Laniarius liberatus (no longer a valid species) and the Bugun Liocichla
Bugun Liocichla
The Bugun Liocichla, Liocichla bugunorum, is a passerine bird species from the Old World babbler family closely related to the Grey-faced Liocichla. First spotted in 1995, it was described as a new species in 2006 by Ramana Athreya. The description was made without the collection of a type...

 Liocichla bugunorum, using blood, DNA and feather samples as the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 material.

Other methods of preservation include the storage of specimens in spirit. Such wet-specimens have special value in physiological and anatomical study, apart from providing better quality of DNA for molecular studies. Freeze drying
Freeze drying
Freeze-drying is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport...

 of specimens is another technique that has the advantage of preserving stomach contents and anatomy, although it tends to shrink making it less reliable for morphometrics.

In the field


The study of birds in the field was helped enormously by improvements in optics. Photography made it possible to document birds in the field with great accuracy. High power spotting scopes today allow observers to detect minute morphological differences that were earlier possible only by examination of the specimen in the hand.

The capture and marking of birds enables detailed studies of life-history. Techniques for capturing birds are varied and include the use of bird liming
Birdlime
Birdlime is an adhesive substance used in trapping birds. It is spread on a branch or twig, upon which a bird may land and be caught. Its use is illegal in many jurisdictions....

 for perching birds, mist net
Mist net
Mist nets are used by ornithologists and bat biologists to capture wild birds and bats for banding or other research projects. Mist nets are typically made of nylon mesh suspended between two poles, resembling an oversized volleyball net. When properly deployed, the nets are virtually invisible...

s for woodland birds, cannon netting
Cannon netting
Cannon-netting is a method of catching large numbers of animals, often birds, usually to band them, or otherwise tag them, as well as acquiring biometric data , in order to find out about their movements, migration routes, survival rates and metabolism...

 for open area flocking birds, the bal-chatri
Bal-chatri
Bal-chatri traps are designed to catch birds of prey . The use of such traps is one of the most effective ways of catching free-flying raptors. Modified bal-chatri traps are also used for catching shrikes.-History:...

 trap for raptors, decoys and funnel traps
Heligoland trap
A Heligoland trap is a large, building-sized, funnel-shaped, rigid structure of wire mesh or netting used to trap birds, so that they can be banded or otherwise studied by ornithologists....

 for water birds.

The bird in the hand may be examined and measurements
Morphometrics
Morphometrics refers to the quantitative analysis of form, a concept that encompasses size and shape. Morphometric analyses are commonly performed on organisms, and are useful in analyzing their fossil record, the impact of mutations on shape, developmental changes in form, covariances between...

 can be made including standard lengths and weight. Feather moult and skull ossification provide indications of age and health. Sex can be determined by examination of anatomy in some sexually non-dimorphic species. Blood samples may be drawn to determine hormonal conditions in studies of physiology, identify DNA markers for studying genetics and kinship in studies of breeding biology and phylogeography. Blood may also be used to pathogens and arthropod borne viruses. Ectoparasites may be collected for studies of coevolution and zoonoses. In many of cryptic species, measurements (such as the relative lengths of wing feathers in warblers) are vital in establishing identity.

Captured birds are often marked for future recognition. Rings or bands
Bird ringing
Bird ringing or bird banding is a technique used in the study of wild birds, by attaching a small, individually numbered, metal or plastic tag to their legs or wings, so that various aspects of the bird's life can be studied by the ability to re-find the same individual later...

 provide long-lasting identification but require capture for the information on them to be read. Field identifiable marks such as coloured bands, wing tags or dyes enable short-term studies where individual identification is required. Mark and recapture
Mark and recapture
Mark and recapture is a method commonly used in ecology to estimate population size. This method is most valuable when a researcher fails to detect all individuals present within a population of interest every time that researcher visits the study area...

 techniques make demographic studies possible. Ringing has traditionally been used in the study of migration. In recent times satellite transmitters provide the ability to track migrating birds in near real-time.

Techniques for estimating population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

 include point counts, transect
Transect
A transect is a path along which one records and counts occurrences of the phenomena of study .It requires an observer to move along a fixed path and to count occurrences along the path and, at the same time, obtain the distance of the object from the path...

s and territory mapping. Observations are made in the field using carefully designed protocols and the data may be analysed to estimate bird diversity, relative abundance or absolute population densities. These methods may be used repeatedly over large time spans to monitor changes in the environment. Camera trap
Camera trap
A camera trap is a remotely activated camera that is equipped with a motion sensor or an infrared sensor, or uses a light beam as a trigger. Camera trapping is a method for capturing wild animals on film when researchers are not present, and has been used in ecological research for decades...

s have been found to be a useful tool for the detection and documentation of elusive species, nest predators and in the quantitative analysis of frugivory, seed dispersal and behaviour.

In the laboratory



Many aspects of bird biology are difficult to study in the field. These include the study of behavioural and physiological changes that require a long duration of access to the bird. Non-destructive samples of blood or feathers taken during field studies may be studied in the laboratory. For instance, the variation in the ratios of stable hydrogen isotopes across latitudes makes it possible to roughly establish the origins of migrant birds using mass spectrometric
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...

 analysis of feather samples. These techniques can be used in combination with other techniques such as ringing.

The first attenuated vaccine developed by Louis Pasteur
Louis Pasteur
Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...

 was for fowl cholera and was tested on poultry in 1878. Poultry continues to be used as a model for many studies in non-mammalian immunology.

Studies in bird behaviour include the use of tamed and trained birds in captivity. Studies on bird intelligence
Bird intelligence
Bird intelligence deals with the definition of intelligence and its measurement as it applies to birds. Traditionally, birds have been considered inferior in intelligence to mammals, and derogatory terms such as bird brains have been used colloquially in some cultures. Such perceptions are no...

 and song learning have been largely laboratory based. Field researchers may make use of a wide range of techniques such as the use of dummy owls to elicit mobbing behaviour, dummy males or the use of call playback to elicit territorial behaviour and thereby to establish the boundaries of bird territories.

Studies of bird migration
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 including aspects of navigation, orientation and physiology are often studied using captive birds in special cages that record their activities. The Emlen funnel
Emlen funnel
An Emlen funnel is a bird cage shaped like an inverted cone, used to study bird behaviour, in particular birds' migratory instincts. It is named after S T and J T Emlen who introduced the technique in 1966. An ink pad is placed on the bottom, so when the bird hops or flutters onto the sloping walls...

 for instance makes use of a cage with an inkpad at the centre and a conical floor where the ink marks can be counted to identify the direction in which the bird attempts to fly. The funnel can have a transparent top and visible cues such as the direction of sunlight may be controlled using mirrors or the positions of the stars simulated in a planetarium
Planetarium
A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation...

.

The entire genome of the domestic fowl Gallus gallus was sequenced in 2004 and was followed in 2008 by the genome of the Zebra Finch (Taeniopygia guttata). Such whole genome sequencing projects allow for studies on evolutionary processes involved in speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

. Associations between the expression of genes and behaviour may be studied using candidate genes. Variations in the exploratory behaviour of Great Tits (Parus major) have been found to be linked with a gene orthologous to the human gene DRD4 (Dopamine receptor D4) which is known to be associated with novelty-seeking behaviour. The role of gene expression in developmental differences and morphological variations have been studied in Darwin's finches
Darwin's finches
Darwin's finches are a group of 14 or 15 species of passerine birds. It is still not clear which bird family they belong to, but they are not related to the true finches. They were first collected by Charles Darwin on the Galápagos Islands during the second voyage of the Beagle...

. The difference in the expression of Bmp4 have been shown to be associated with changes in the growth and shape of the beak.

The chicken has long been a model organism
Model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...

 for studying vertebrate developmental biology
Developmental biology
Developmental biology is the study of the process by which organisms grow and develop. Modern developmental biology studies the genetic control of cell growth, differentiation and "morphogenesis", which is the process that gives rise to tissues, organs and anatomy.- Related fields of study...

. As the embryo is readily accessible, its development can be easily followed (unlike mice
House mouse
The house mouse is a small rodent, a mouse, one of the most numerous species of the genus Mus.As a wild animal the house mouse mainly lives associated with humans, causing damage to crops and stored food....

). This also allows the use of electroporation
Electroporation
Electroporation, or electropermeabilization, is a significant increase in the electrical conductivity and permeability of the cell plasma membrane caused by an externally applied electrical field...

 for studying the effect of adding or silencing a gene. Other tools for perturbing their genetic makeup are chicken embryonic stem cell
Embryonic stem cell
Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of the blastocyst, an early-stage embryo. Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells...

s and viral vector
Viral vector
Viral vectors are a tool commonly used by molecular biologists to deliver genetic material into cells. This process can be performed inside a living organism or in cell culture . Viruses have evolved specialized molecular mechanisms to efficiently transport their genomes inside the cells they infect...

s.

Collaborative studies



With the widespread interest in birds, it has been possible to use a large number of people to work on collaborative ornithological projects that cover large geographic scales. These citizen science
Citizen science
Citizen science is a term used for the systematic collection and analysis of data; development of technology; testing of natural phenomena; and the dissemination of these activities by researchers on a primarily avocational basis...

 projects include nation-wide projects such as the Christmas Bird Count
Christmas Bird Count
The Christmas Bird Count is a census of birds in the Western Hemisphere, performed annually in the early Northern-hemisphere winter by volunteer birders...

, Backyard Bird Count, the North American Breeding Bird Survey
Breeding Bird Survey
A breeding bird survey monitors the status and trends of bird populations. Data from the survey are an important source for the range maps found in field guides. The North American Breeding Bird Survey is a joint project of the United States Geological Survey and the Canadian Wildlife Service...

, the Canadian EPOQ or regional projects such as the Asian Waterfowl Census and Spring Alive in Europe. These projects help to identify distributions of birds, their population densities and changes over time, arrival and departure dates of migration, breeding seasonality and even population genetics. The results of many of these projects are published as bird atlas
Bird atlas
A bird atlas is an ornithological work that attempts to provide information on the distribution, abundance, long-term change as well as seasonal patterns of bird occurrence and usually represented in the form of maps...

es. Studies of migration using bird ringing or colour marking often involve the cooperation of people and organizations in different countries.

Applications



Wild birds impact many human activities while domesticated birds are important sources of eggs, meat, feathers and other products. Applied and economic ornithology aim to reduce the ill effects of problem birds and enhance gains from beneficial species.

The role of some species of birds as pests has been well known, particularly in agriculture. Granivorous birds such as the quelea
Quelea
Quelea is a small genus of passerine birds that belongs to the weaver family Ploceidae, confined to Africa. These are small-sized, sparrow- or finch-like gregarious birds, with bills adapted to eating seeds...

s in Africa are among the most numerous birds in the world and foraging flocks can cause devastation. Many insectivorous birds are also noted as beneficial in agriculture. Many early studies on the benefits or damages caused by birds in fields were made by analysis of stomach contents and observation of feeding behaviour. Modern studies aimed to manage birds in agriculture make use of a wide range of principles from ecology. Intensive aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

 has brought humans in conflict with fish-eating birds such as cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...

s.

Large flocks of pigeons and starlings in cities are often considered as a nuisance and techniques to reduce their populations or their impacts are constantly innovated. Birds are also of medical importance and their role as carriers of human diseases such as Japanese Encephalitis
Japanese Encephalitis
Japanese encephalitis —previously known as Japanese B encephalitis to distinguish it from von Economo's A encephalitis—is a disease caused by the mosquito-borne Japanese encephalitis virus. The Japanese encephalitis virus is a virus from the family Flaviviridae. Domestic pigs and wild birds are...

, West Nile Virus
West Nile virus
West Nile virus is a virus of the family Flaviviridae. Part of the Japanese encephalitis antigenic complex of viruses, it is found in both tropical and temperate regions. It mainly infects birds, but is known to infect humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, domestic...

 and H5N1
H5N1
Influenza A virus subtype H5N1, also known as "bird flu", A or simply H5N1, is a subtype of the influenza A virus which can cause illness in humans and many other animal species...

 have been widely recognised. Bird strike
Bird strike
A bird strike—sometimes called birdstrike, avian ingestion , bird hit, or BASH —is a collision between an airborne animal and a man-made vehicle, especially aircraft...

s and the damage they cause in aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...

 are of particularly great importance, due to the fatal consequences and the level of economic losses caused. It has been estimated that the airline industry incurs worldwide damages of US $ 1.2 billion each year.

Many species of birds have been driven to extinction by human activities. Being conspicuous elements of the ecosystem, they have been considered as indicators of ecological health. They have also helped in gathering support for habitat conservation
Habitat conservation
Habitat conservation is a land management practice that seeks to conserve, protect and restore, habitat areas for wild plants and animals, especially conservation reliant species, and prevent their extinction, fragmentation or reduction in range...

. Bird conservation
Bird conservation
Bird conservation is a field in the science of conservation biology related to threatened birds. Humans have had a profound effect on many bird species...

 requires specialized knowledge in aspects of biology, ecology and may require the use of very location specific approaches. Ornithologists contribute to conservation biology
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...

 by studying the ecology of birds in the wild and identifying the key threats and ways of enhancing the survival of species. Critically endangered species such as the California Condor
California Condor
The California Condor is a New World vulture, the largest North American land bird. Currently, this condor inhabits only the Grand Canyon area, Zion National Park, and coastal mountains of central and southern California and northern Baja California...

 have had to be captured and bred in captivity. Such ex-situ conservation
Ex-situ conservation
Ex-situ conservation means literally, "off-site conservation". It is the process of protecting an endangered species of plant or animal outside of its natural habitat; for example, by removing part of the population from a threatened habitat and placing it in a new location, which may be a wild...

 measures may be followed by re-introduction of the species into the wild.

See also


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