[2] In 1869, he was persuaded by Richard Bowdler Sharpe to illustrate his Monograph of the Alcedinidae, or Family of Kingfishers (1868-1871) and to move to England,[3] where he lived for the rest of his life.

His notes and findings on the island of Principe, along with those of his colleague Dr. H. Dohrn, would eventually become the basis for a later description of a rare ibis, Lampribis rothschildi Bannerman.

Tony Keulemans later wrote Beyond the grave, which tells the story of a remarkable discovery of a painting John Gerrard had made of his own gravestone.

And finally, Tony Keulemans wrote an errata list to Feathers to Brush, which includes additional literature references and new genealogical findings.

Keulemans's work is characterised by its consistency, showing little change over the course of his career, and focused to an extraordinary degree on the rendering of fine detail.

Aside from this, a number of critics have rightly placed Keulemans above his contemporaries;[7] his ability to create accurate and vivid representations of birds gave him prominence in his field.

Keulemans' first prints appeared in two books by Francois Pollen, Contributions a l'histoire naturelle des Lemuriens (1867) and Een blik in Madagascar (1867).

The vast majority of these were vignettes published within octavo-size books and publications, and a great number of his works also appeared in quarto (Dresser/Europe) and in folio (Seebohm/Turdidae and DuCane Godman/Petrels).

Most of the illustrations by Keulemans were produced through traditional lithography, allowing for a finished product that depicts a vivid, lifelike figure through depth and tone.

[14] Many other chapters of Onze vogels in huis en tuin also show that Keulemans was a careful observer of the species he painted and described.

In an article in the Bristol Mercury and Daily Post of 3 March 1883, Keulemans tells how he and his family were living in Paris in December 1880 when there was an outbreak of smallpox.

[15][page needed] Subsequently, Keulemans experienced further incidents increasing his belief in the supernatural, in particular which he claimed could be awakened via the painting of a bird's eye.