Bartlett supported D. W. Mitchell on the idea that the collection of animals held by the Zoological Society of London could be made accessible to the public for a small fee that could help the society. It was open on Mondays for a fee of six pence. Queen Victoria gave him a gold watch for taking care of her pet birds. Dead birds were sent to him for taxidermic preservation, and for his excellent exhibits, he received a gold medal at the Great Exhibition of 1851. He was among the first to reconstruct a specimen of the dodo, and this was displayed at Sydenham Crystal Palace, where he was also appointed naturalist around 1852. The restoration was destroyed, though, in the 1866 fire. He associated himself with the Zoological Society and was offered the position of superintendent made vacant by the death of John Thompson at the garden in Regents Park in 1859. As superintendent, Bartlett became a familiar figure for visiting naturalists and corresponded with many across the world. He was an agent for the acquisition of wild animals from suppliers such as Edward Blyth and was involved in their sale to circus agents such as P.T. Barnum. He kept the position at the zoo, and became a familiar figure until his death. He became an authority on the care of wild animals and published papers in the" Proceedings of the Zoological Society" and other journals. He received a silver medal by the Zoological Society in 1872 and was made an associate of the Linnean Society in 1879. Charles Darwin often discussed his ideas on sexual selection with Bartlett. He noted, for instance: "I asked Mr. Bartlett, of the Zoological Gardens, who has had very large experience with birds, whether the male tragopan (one of the Gallinaceae) was polygamous, and I was struck by his answering, 'I do not know, but I should think so from his splendid colours.'" When Darwin was studying the facial expressions of wild animals, he was introduced to the artistic and observational abilities of Joseph Wolf by Bartlett. Wolf was able to make illustrations of fleeting facial expressions for Darwin, although Wolf himself had reservations about Darwin's interpretations.