The Ornithological Dictionary; or Alphabetical Synopsis of British Birds was written by the English naturalist and army officer George Montagu, and first published by J.

It was one of the texts, along with Thomas Bewick's contemporaneous A History of British Birds (2 volumes, 1797 and 1804) that made ornithology popular in Britain, and, with the 1676 Ornithologia libri tres of Francis Willughby and John Ray, helped to make it the object of serious study.

[6] Montagu states that the "sheets have been entirely drawn from our own observations, and compiled from the notes of twenty years search and attention ... in most parts of this kingdom", mentioning woods, mountains and "barren waste", rivers and lakes.

He records that the species is indigenous to Devon and "confined to the southern parts of that county contiguous to the coast",[8] as it remains in the twentyfirst century.

...[8]The rest of the entry is written in continuous prose, starting with a physical description giving length, weight, and a detailed account of plumage with differences between the sexes (more than a page in the cirl bunting's case).

[12] Terms range from the Cere, "the naked skin that covers the base of the bill in the Hawk kind" to "Pes compedes", "When the legs are placed so far behind as to be rendered almost useless in walking, as in the Grebes and Divers".

He criticises Montagu's grouping of all species of a genus together, as with "Duck-Eider, Duck-King" as "an unnecessary awkwardness, attended with no apparent advantage", and instead lists them as written.

[20] The botanist John Templeton is recorded in the Dictionary of National Biography to have made marginal notes in his copy of Montagu.

[21] In 1831, "J. D." wrote to The Magazine of Natural History, and Journal of Zoology, Botany, Mineralogy, Geology, and Meteorology about James Rennie's second edition "to point out a few of its faults".

He then asks rhetorically whether anyone can identify a bird using the second edition, answering his own question with "that he can do so, no one will, I think, have the hardihood to advance" and hence that "The book, viewed in this light, appears to be a complete failure.

Also in 1831, the ornithologist William Swainson wrote a hostile review of Rennie's edition for the Philosophical Magazine, commenting that we were struck with the extreme assumption and arrogance of the whole style of treating his subject, which is here displayed by the author [Rennie]; with the bitterness and contempt of his vituperation of the naturalists whose views he condemns, disingenuously mingled with praise, which on his own showing must be undeserved; and with the perverse ignorance from which alone such misrepresentations as he makes on all the subjects which he touches, could have arisen.

[26] Charles Darwin quoted from Montagu's account of the role of birdsong in his 1871 Selection in Relation to Sex, commenting that "Few more careful observers ever lived".

[27][28] W. H. Mullens, in a 1908 issue of British Birds, argued that despite the contributions of Thomas Pennant, of Gilbert White's Natural History of Selborne (1789), and Thomas Bewick's fine wood engravings in A History of British Birds (1797–1804), ornithology had not made much progress since the seventeenth century.

[19] Instead, it was not until the genius of George Montagu produced in 1802 the 'Ornithological Dictionary' that the work which had been begun by Willughby and Ray [with their Ornithologia libri tres], was properly continued.

[19]The ornithologist and ethologist David Lack, writing in 1944, praises the book as "a necessary corrective to the ornate and often inaccurate works of the late eighteenth century",[28] adding that Montagu's views on pair formation in songbirds, and the role of birdsong "are remarkably up-to-date.

Lack further wrote that[28] Montagu's correct interpretation of one of the most important functions of bird song did not acquire general recognition until ... over a hundred years later.

[28]Stephen Moss evaluates Montagu's contribution as "of vital importance" to the growth of birdwatching, writing in 2005 that[29] To the modern birder, possessed of the latest field guide with its many hundreds of species, together with full-colour plates and distribution maps, Montagu's achievements may seem a mere footnote in ornithological history.

[29] Mark Cocker and Richard Mabey in their Birds Britannica note that Montagu took the association of the distribution and lifestyle of the stone curlew and the great bustard to mean that they were closely related.