1,039 articles
Northern cardinal
Northern cardinal (Cardinalis cardinalis), also redbird or cardenal rojo, a non-migratory red-crested songbird of eastern North America; about 130 million birds, increasing 0.32% yearly, IUCN Least Concern, state bird of seven U.S. states.
Northern flicker
Northern Flicker (Colaptes auratus), a large ground-foraging North American woodpecker that eats ants and beetles. Yellow-shafted and Red-shafted groups hybridize from Alaska to Texas; Guatemalan Flicker split in 2024.
Northern gannet
Northern gannet (Morus bassanus), largest seabird of the North Atlantic, family Sulidae. Plunge-dives from over 100 feet at 60 mph; breeds in six Canadian and 32 European colonies; 2022 avian influenza cut Bass Rock by about 30%.
Northern mockingbird
Northern mockingbird (Mimus polyglottos), a Mimidae songbird resident across the continental U.S. and Mexico, known for lifelong song learning, roughly 200-song repertoires, mimicry of birds and frogs, and bold nest defense.
Nucifraga
Nucifraga (nutcrackers) is a corvid bird genus, Brisson 1760, with four species after the 2024 Eurasian split: Northern, Clark's, Southern, and Kashmir Nutcrackers, defined by pine-seed caching, a sublingual seed pouch, and keystone pine seed dispersal.
Numenius
Numenius (curlews and whimbrels), genus Brisson 1760 of nine Scolopacidae shorebird species with long decurved bills; two species extinct, slender-billed curlew declared Extinct 2025, Far Eastern curlew Critically Endangered.
Numida
Numida, guineafowl genus erected by Linnaeus in 1764, family Numididae, order Galliformes; monotypic for the helmeted guineafowl Numida meleagris, an African bird domesticated about 2,000 years ago in Mali and Sudan.
Nuthatch
Nuthatches (genus Sitta, family Sittidae) are small Northern Hemisphere passerine birds that climb down trunks headfirst and wedge nuts in bark to open them; 24 species, most diverse in southern Asia, with six Eurasian nuthatch lineages.
Nycticorax
Nycticorax (night herons), genus of Ardeidae herons erected by Forster 1817; type species black-crowned night heron Nycticorax nycticorax, worldwide except Australia, IUCN Least Concern, 440,000-1,990,000 mature individuals.
Oceanites
Oceanites is a genus of austral storm-petrels (Oceanitidae) erected by Keyserling & Blasius, 1840, type species Wilson's storm-petrel O. oceanicus; also the name of a DC-based Antarctic penguin research nonprofit founded 1987.
Ocreatus
Ocreatus, Gould 1846, is a genus of Andean racket-tail hummingbirds (Trochilidae). Once one species with eight subspecies, a 2016 Zootaxa revision split it into four species; current checklists recognize three: White-booted, Peruvian, and Rufous-booted Racket-tail.
Oena
Oena is a monotypic dove genus (Swainson, 1837) holding the Namaqua Dove, Oena capensis, a 28 cm arid-zone columbid of sub-Saharan Africa, Madagascar, and Arabia, Least Concern with an increasing, northward-expanding population.
Old World sparrow
Old World sparrows (Passeridae): house sparrow, Eurasian tree sparrow, snowfinches. Small brown seed-eating passerines native to Eurasia and Africa, unrelated to New World sparrows (Passerellidae), widely introduced.
Old World vulture
Old World vultures: 16 Accipitridae vulture species of Africa and Eurasia, convergent with New World vultures; obligate scavengers now among the most threatened bird groups due to poisoning, diclofenac, and belief-based use.
Oriental magpie-robin
Oriental magpie-robin (Copsychus saularis, 鵲鴝), a 19–21 cm black-and-white Muscicapidae songbird from Pakistan to south China and Southeast Asia; IUCN Least Concern, endangered in Singapore.
Origin of birds
Origin of birds: birds evolved from maniraptoran theropod dinosaurs, established by Ostrom's 1976 Archaeopteryx work and Gauthier's 1986 cladistics; feathers and flight-related traits predate birds, with flight origin still debated.
Oriolus
Oriolus is the Linnaean 1766 genus of Old World orioles in the family Oriolidae, spanning Africa, Eurasia, and Australasia; its type species is the Eurasian Golden Oriole Oriolus oriolus, a Least Concern migrant, distinct from unrelated American icterid orioles.
Oriolus oriolus
Oriolus oriolus, the Eurasian golden oriole (also common golden oriole, pirol), a Palearctic-migrating Oriolidae passerine breeding in Europe and wintering in Africa; only Old World oriole breeding in temperate Northern Hemisphere; IUCN Least Concern.
Ornithology
Ornithology, the scientific study of birds, from Aristotle and Ray and Willughby's 1678 Ornithology through Linnaean taxonomy, Audubon, and modern citizen science (eBird) and bird conservation research.
Ortalis
Ortalis, the chachalacas, is a genus of Merrem, 1786 in the Cracidae (Galliformes), with about 12 American species 42–67 cm long; molecular work places it sister to curassows, and Ortalidini was conserved by ICZN Opinion 2456.
Ortalis vetula
Ortalis vetula, the plain chachalaca (chachalaca norteña), is an arboreal cracid of the Gulf-Caribbean slope from southern Texas to Costa Rica, named for its loud cha-cha-lac chorus; IUCN Least Concern, about 2 million birds.
Ortolan bunting
Ortolan bunting (Emberiza hortulana), a 16.5 cm migratory bunting breeding from Spain to Mongolia and wintering in sub-Saharan Africa. Two flyways split at a Belarus-to-Serbia divide; European population fell about 92%, the steepest of any European bird.
Osprey
Osprey (Pandion haliaetus), also Western Osprey or fish hawk: a cosmopolitan raptor, sole species of family Pandionidae, feeding almost entirely on live fish caught by feet-first dives; rebounded after the 1972 DDT ban but now faces Chesapeake Bay reproduction declines linked to menhaden.
Ostrich
The ostrich (Struthio camelus) is a large flightless bird native to African grasslands and savannas, the tallest and heaviest living bird, able to sprint at 69 km/h.
Otus
Otus is the Old World scops-owl genus of small tufted Strigidae owls, the most speciose owl genus with about 51 species; type species Otus scops, species limits set mainly by voice.
Otus ireneae
Otus ireneae, the Sokoke Scops Owl or Morden's Scops-owl, is Africa's smallest owl (15 cm), an Endangered beetle-eating forest specialist confined to Arabuko-Sokoke, Dakatcha, and the East Usambaras.
Otus scops
Otus scops, the Eurasian or Common Scops Owl, is a small 90 g migratory owl breeding from southern Europe to Pakistan and wintering in sub-Saharan Africa; insectivorous, cavity-nesting, five subspecies, IUCN Least Concern.
Oviraptoridae
Oviraptoridae, an Asian Late Cretaceous family of feathered, toothless theropod dinosaurs including Oviraptor and Citipati; named "egg thief" in error, they are now known to have brooded ring-shaped nests of their own eggs.
Owl
Owl (order Strigiformes): nocturnal birds of prey in families Tytonidae and Strigidae, 200-254 species worldwide except Antarctica; known for fixed tubular eyes, 270-degree head rotation, asymmetric ears, silent flight, and pellet-forming carnivory.
Owl aviaries
Owl aviaries are large enclosed enclosures for owls in zoos, sanctuaries, and rehabilitation centers, requiring covered tops, species-appropriate perching, and separate breeding enclosures; modern standards phase out tethering by 2030 in favor of free-lofted aviaries.