Ornithology is the science of studying birds. It includes many biological disciplines, like taxonomy, behavioral studies (ethology), species distribution, ecology and many other branches of biology focused on birds. Among the taxon-focused biological sciences, ornithology enjoys the greates number of amateur biologists or birdwatchers applying scientifically sound methodologies. There is no doubt this has to do with the visibility of birds and the glamour of some of the more colourful species. While not all amateurs study birds scientifically, birdwatching is considered the most popular outdoors recreational activity in the world, with more that 50 000 000 birders in North America Alone.
Ornithology has let the way to the development of many concepts in taxonomy, evolution, ethology and ecology such as the definition of species, the process of speciation, instinct, learning, ecological niches, conservation. While early ornithology was principally concerned with descriptions and distributions of species, ornithologists today seek answers to many specific questions, often using birds as models to test hypotheses or predictions based on theories. A wide range of tools and techniques are used in ornithology, but some basic equipment includes: binoculars, field guides, ipods with bird songs and telescopes.
Ornithology took off as a popular science during the 19th century with the popularity of natural history as a passtime for high society, and the collection of natural objects such as bird eggs and skins. During those early days, ornithology was primarily focused on the geographical distributions, the taxonomic distinction and the identification of birds based on collected specimens. The collections of museums and private collectors grew with contributions from various parts of the world.
The study of birds in their habitats was particularly advanced in Germany with bird ringing stations established as early as 1903. By the 1920s the Journal für Ornithologie included many papers on the behaviour, ecology, anatomy and physiology, while ornithology in the United States continued to be dominated by museum studies of morphological variations, species identities and geographic distributions. 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 and newer quantitative approaches were introduced for the study of ecology and behaviour.
The study of imprinting behaviour in ducks and geese by Konrad Lorenz and the studies of instinct in Herring Gulls by Nicolaas Tinbergen, led to the establishment of the field of ethology. The study of learning became an area of interest and the study of bird song 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.
The new tools of molecular-biology changed the study of bird systematics. Systematics changed from being based on phenotype to the underlying genotype. The use of techniques such as DNA-DNA hybridization to study evolutionary relationships was pioneered by Charles Sibley and Jon Edward Ahlquist resulting in what is called the Sibley-Ahlquist taxonomy. These early techniques have been replaced by mitochondrial DNA sequencing and molecular phylogenetics approaches that make use of computational procedures for sequence alignment, construction of phylogenetic trees and calibration of molecular clocks to infer evolutionary relationships. Many new species have been identified on the basis of these thechniques, while some have been downgraded to the level of subspecies.
The use of binoculars and telescopes for bird observation began in the 1820s and 1830s with pioneers like J. Dovaston (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 in ornithology. The early guides were large and cumbersome and were mainly focused on identifying specimens in the hand. This changed with the new field guides by Roger Tory Peterson.
Birding 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 (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 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.
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. Powerful digital cameras allow instantaneous documentation and peer review by colleagues across the globe.
Captured birds are often marked for future recognition. Rings or bands 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 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.
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 regions. These citizen science projects include nation-wide projects such as the Christmas Bird Count, Backyard Bird Count, the North American Breeding Bird Survey, 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. These citizen science projects have clearly narrowed the gap the gap between the wonderful passtime of birdwatching and the science of ornothology, while many birdwatchers are better at identifying birds in th field than their academic counterpart ornithologists.