Hume made several expeditions almost solely to study ornithology the largest being an expedition to the Indus area in late November 1871 and continued until the end of February 1872. In March 1873, he visited the Andaman and Nicobar Islands in the Bay of Bengal along with geologists Dr. Ferdinand Stoliczka and Dr. Dougall of the Geological Survey of India and James Wood-Mason of the Indian Museum in Calcutta. In 1875, he made an expedition to the Laccadive Islands aboard the marine survey vessel IGS "Clyde" under the command of Staff-Commander Ellis. The official purpose of the visit being to examine proposed sites for lighthouses. During this expedition Hume collected many bird specimens, apart from conducting a bathymetric survey to determine whether the island chain was separated from India by a deep canyon. And in 1881 he made his last ornithological expedition to Manipur, a visit in which he collected and described the Manipur bush quail ("Perdicula manipurensis"), a bird that has remained obscure with few reliable reports since. Hume spent an extra day with his assistants cutting down a large tract of grass so that he could obtain specimens of this species. This expedition was made on special leave following his demotion from the Central Government to a junior position on the Board of Revenue of the North Western Provinces. Apart from personal travel, he also sent out a trained bird-skinner to accompany officers travelling in areas of ornithological interest such as Afghanistan. Around 1878 he was spending about £1500 a year on his ornithological surveys.