Birds are a group of warm-blooded vertebrates constituting the class Aves, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5.5 cm (2.2 in) bee hummingbird to the 2.8 m common ostrich. There are over 11,000 living species, more than half of which are passerine, or "perching" birds. Birds have wings whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds. Wings, which are modified forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in some birds, including ratites, penguins, and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming. The study of birds is called ornithology.
Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds. It has also been an area with a large contribution made by amateurs in terms of time, resources, and financial support. Studies on birds have helped develop key concepts in biology including evolution, behaviour and ecology such as the definition of species, the process of speciation, instinct, learning, ecological niches, guilds, island biogeography, phylogeography, and conservation.
Seabirds 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 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.
The razorbill, razor-billed auk, or lesser auk is a North Atlantic colonial seabird and the only extant member of the genus Alca of the family Alcidae, the auks. It is the closest living relative of the extinct great auk.
In ecology, the competitive exclusion principle, sometimes referred to as Gause's law, is a proposition that two species which compete for the same limited resource cannot coexist at constant population values. When one species has even the slightest advantage over another, the one with the advantage will dominate in the long term. This leads either to the extinction of the weaker competitor or to an evolutionary or behavioral shift toward a different ecological niche. The principle has been paraphrased in the maxim "complete competitors can not coexist".
David Lambert Lack FRS was a British evolutionary biologist who made contributions to ornithology, ecology, and ethology. His 1947 book, Darwin's Finches, on the finches of the Galapagos Islands was a landmark work as were his other popular science books on Life of the Robin and Swifts in a Tower. He developed what is now known as Lack's Principle which explained the evolution of avian clutch sizes in terms of individual selection as opposed to the competing contemporary idea that they had evolved for the benefit of species. His pioneering life-history studies of the living bird helped in changing the nature of ornithology from what was then a collection-oriented field. He was a longtime director of the Edward Grey Institute of Field Ornithology at the University of Oxford.
Christopher Miles Perrins, is Emeritus Fellow of the Edward Grey Institute of Field Ornithology at the University of Oxford, Emeritus Fellow at Wolfson College, Oxford and His Majesty's Warden of the Swans since 1993.
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. These collections are archives of avian diversity and serve the diverse needs of scientific researchers, artists, and educators. Collections may include a variety of preparation types emphasizing preservation of feathers, skeletons, soft tissues, or (increasingly) some combination thereof. Modern collections range in size from small teaching collections, such as one might find at a nature reserve visitor center or small college, to large research collections of the world's major natural history museums, the largest of which contain hundreds of thousands of specimens. Bird collections function much like libraries, with specimens arranged in drawers and cabinets in taxonomic order, curated by scientists who oversee the maintenance, use, and growth of collections and make them available for study through visits or loans.
Ian Newton is an English ornithologist.
John Weaver Fitzpatrick is an American ornithologist primarily known for his research work on the South American avifauna and for the conservation of the Florida scrub jay. He is currently the Louis Agassiz Fuertes Director of the Cornell Lab of Ornithology in Ithaca, New York.
Anurag Agrawal is an American professor of ecology, evolutionary biology, and entomology who has written over a 150 peer-reviewed articles, which earned him an h-index of 92. He is the author of a popular science book, Monarchs and Milkweeds from Princeton University Press, and is currently the James Alfred Perkins Professor of Environmental Studies at Cornell University.
Ellen D. Ketterson is an American evolutionary biologist, behavioral ecologist, neuroendocrinologist and ornithologist best known for her experimental approach to the study of life-history trade-offs in a songbird, the Dark-eyed Junco. She is currently a Distinguished Professor of Biology, Director of the Environmental Resilience Institute, and affiliate professor in Cognitive Science, Gender Studies, Integrative Study of Animal Behavior, and Neuroscience at Indiana University.
Ben C. Sheldon is the Luc Hoffmann Chair in Field Ornithology and Director of the Edward Grey Institute of Field Ornithology of the University of Oxford's Department of Zoology. He was Head of the Department of Zoology between 2016 and 2021.
Donald Eugene Kroodsma is an American author and ornithologist, one of the world's leading experts on the science of birdsong.
Allison K. Shaw is an American ecologist and professor at the University of Minnesota. She studies the factors that drive the movements of organisms.
Patricia Monaghan is Regius Professor of Zoology in the Institute of biodiversity, animal health & comparative medicine at the University of Glasgow.
Taxon cycles refer to a biogeographical theory of how species evolve through range expansions and contractions over time associated with adaptive shifts in the ecology and morphology of species. The taxon cycle concept was explicitly formulated by biologist E. O. Wilson in 1961 after he surveyed the distributions, habitats, behavior and morphology of ant species in the Melanesian archipelago.
Wesley Edwin "Bud" Lanyon (1926–2017) was an American ornithologist.
James Roger King (1927–1991) was an American ornithologist, specializing in avian physiology.
Jessica Gurevitch is a plant ecologist known for meta-analysis in the fields of ecology and evolution.
