John Gerrard Keulemans (1842-1912) produced thousands of drawings and lithographic plates for over one hundred major bird books and ornithological journals. With his skill as an artist and lithographer, and his excellent observation as a naturalist, J.G. Keulemans will always hold his status as one of the greatest of all ornithological illustrators. The compositions of many of his lithographs are given greater personality by his inclusion of female as well as (usually more colourful) male, and greater sensitivity by including birds with their young, their nests, habitat foliage, fruit and insects or other food.
John Gerrard Keulemans (1842-1912), was trained in Rotterdam, in the family tradition of garment embroidery. From his youth, John Gerrard was interested in natural history, particularly birds. Like Gould before him, Keulemans studied the taxidermy 
of birds before he developed his artistic skills. Keulemans lacked formal higher education, but the Director of the Rijksmuseum of Natural History at Leyden in Holland, Dr Hermann Schlegel, encouraged him in his study of anatomy and the scientific representation of birds. When 22 and supporting himself by providing birds and their feathers for millinery (and the embellishment of the fabulous head attire of the period), Keulemans appealed to Dr Schlegel for more important work.
Schlegel recommended Keulemans for the position of scientific illustrator, travelling to West Africa with the expedition by German biologist, W.L.H. Dohrn. After exploring areas around their base, Keulemans travelled further afield with an African native guide. As well as recording birds they found, Keulemans 
gathered botanical specimens for accurate illustration of their habitats. After repeated bouts of fever in 1866 John Gerrard returned to Europe. In the Dutch Journal of Zoology Keulemans published an article on 64 bird species identified by Dohrn and himself; and zoologists acknowledged Keulemans’ precise scientific documentation of bird-life in Africa.
There was increasing interest in worldwide biological discoveries - particularly in England. Aristocratic enthusiasts, various museums and the Zoological Society sought specimens from all over the world to add to their collections - and they all required illustrations. At that time, all grand publications were drawn and engraved or lithographed by hand, and then watercoloured by hand.
The centre for ornithological publications became London, where John Gould at the Zoological Society had become known as 'the bird man'. Told by Dr Schlegel of Keulemans' fine illustrations, in 1868 the young librarian at the Royal Zoological Society, Richard Bowdler Sharpe, pursuaded John Gerrard Keulemans to move to London to draw and lithograph 120 hand-coloured lithographs for Sharpe's Monograph of the Alcedinidae or Family of Kingfishers. Keulemans moved to London and supported himself by illustrating mainly birds - as a regular illustrator for the Proceedings and Transactions of the Zoological Society and The Ibis, published by the British Ornithological Union. Keulemans' lithographs are usually distinguishable by his monogram JGK on the lithographic plates.
Keulemans' work was of high quality and finer detail and composition than many of his contemporary artists. When Buller’s Birds of New Zealand was published in 1871, Keulemans' lithographic plates were described as “absolutely perfect” in London's The Times newspaper. George Rowley's Ornithological Miscellany, published between 1876 and 1888, included many bird species not previously illustrated - with 127 hand-coloured lithographs by John Gerrard Keulemans. He might have been the most popular ornithological illustrator of his day, but work for a lithographer decreased as technology advanced. Supporting some of his ten surviving children as well as himself, Keulemans continued working and moved to a smaller dwelling. His artistic daughters (closely supervised) often assisted with colouring.
Keulemans’ 163 beautiful hand-coloured lithographs for G.M. Mathews’ The Birds of Australia were among his finest work. Published between 1910 and 1927, and including many newly discovered species, it was one of the last grand works to be superbly illustrated by this exquisitely detailed, slower, skillled process.
The British Birds Rarity Committee obituary, written by Gregory M. Mathews said “… few realized the individuality of the unassuming artist, or recognized that for thirty years he was the unrivalled and unequalled draughtsman of ornithological subjects. From 1870 to 1900, scarcely any ornithologicial work of importance was completed without “illustrations by Keulemans” and his sureness of design combined with a felicity of expression, made his beautiful figures always a delight to refer to.”