27 January – Death of John James Audubon, French-American ornithologist, naturalist and painter who produced the monumental Birds of America5 July – Birth of William Brewster, American ornithologist and cofounder of the American Ornithologists' UnionEmmanuel Le Maout Les Mammifères et les Oiseaux (1851–1854, 2 vol. gr. in-8, illustrés. Showy work for the publishers stand at Exposition Universelle in 1855Birds described in 1851 include the bare-necked umbrellabird, common ʻamakihi, dusky-headed parakeet, Madeira firecrest, Madeiran storm petrel, North Island brown kiwi, olive sparrow, grey-crowned palm-tanager, red-headed fody, rufous-throated tanager, silver-throated tanager, Sri Lanka bush warbler, yellow-bellied tanager and yellow-eared bulbul.
The last Norfolk Island kākā died in captivity in London.
Isidore Geoffroy Saint-Hilaire describes the Elephant bird.
K.k. Naturhistorisches Hofmuseum in Vienna extensively reorganized.Ongoing events
John Gould The birds of Australia; Supplement 1851-69. 1 vol. 81 plates; Artists: J. Gould and H. C. Richter; Lithographer: H. C. RichterJohn Gould The birds of Asia; 1850-83 7 vols. 530 plates, Artists: J. Gould, H. C. Richter, W. Hart and J. Wolf; Lithographers:H. C. Richter and W. Hart 
