During his career in Etawah, he built up a personal collection of bird specimens, however the first collection that he made was destroyed during the 1857 rebellion. After 1857 Hume made several expeditions to collect birds both on health leave and where work took him but his most systematic work began after he moved to Shimla. He was Collector and Magistrate of Etawah from 1856 to 1867 during which time he studied the birds of that area. He later became Commissioner of Inland Customs which made him responsible for the control of of coast from near Peshawar in the northwest to Cuttack on the Bay of Bengal. He travelled on horseback and camel in areas of Rajasthan to negotiate treaties with various local maharajas to control the export of salt and during these travels he took note of the birdlife: