Richard Treacy Henry, the fourth of seven children of John Stephenson Henry, a civil engineer, and his wife, Sarah Anna Treacy, was born at Glanbane House, near Athy, County Kildare, Ireland, on 4 June 1845. The family emigrated to South Australia on the Asia in May 1851, arriving on 31 August. Richard's mother and infant brother died during the journey. John Henry could not find work and on 8 October the family reboarded the Asia for Melbourne. In his search for employment he moved his family frequently around Victoria; they eventually settled in the Warrnambool district of western Victoria.
Henry spent much of his time hunting, fishing, canoeing and making friends with Aboriginals. He watched the seasons change and noted how the abundant wildlife responded. Insatiably curious, he was fascinated by the ecology of the river, swamp, grass and bushlands. He had no formal training in natural history but worked out his own method of studying animal behaviour. In 1866 Henry went into partnership in a sawmilling enterprise with his father at Woodford, Victoria. After the death of a brother at the mill a year later he drifted around the Australian outback, working for a time at a mill in Gunbower county. On 24 October 1872 at Christ Church, Echuca, Victoria, Henry marrried Isabella Curran. Her fate, and that of any children, is unknown.
About 1874 Henry emigrated by himself to New Zealand. Slight but compactly built, agile, somewhat retiring and self-reliant, Henry travelled widely, taking employment where it appealed. He lived in Golden Bay and Taranaki, and on Banks Peninsula before joining the battle to eliminate rabbits on the Middle Dome run in Southland and assisting with the building of a paddle-steamer for the Wakatipu Steam Navigation Company. Then, rejected by the woman he loved, he settled in 1883 at the southern end of Lake Te Anau, building a small dwelling on the lake shore. He took miscellaneous work in the back country, becoming known as a bush guide and explorer and competing unsuccessfully with Quintin McKinnon in finding a route to the West Coast.
In his spare time Henry observed, collected and preserved birds, often analysing their stomach contents to determine their feeding habits. He correctly attributed a loud booming sound heard locally to the kakapo and, noting that its numbers, along with those of the weka, kiwi, teal and whio, declined after the introduction of weasels, stoats and ferrets, predicted the kakapo's extinction. He overcame an initial diffidence about written expression, and turned many of his observations into articles for the Echo, a Dunedin weekly, and, particularly from 1890, for other newspapers. In 1887 he published a pamphlet on The New Zealand rabbit and its prey under the pseudonym 'An Old Acquaintance'; he wrote many letters to the press on the rabbit problem. Writing was to become an important outlet for Henry, who was frustrated by scientists' preference for formal analysis over field observations.
Edward Melland, a Te Anau runholder and member of the Otago Institute, befriended Henry and promoted his increasingly conservationist views among friends who included members of the Otago Acclimatisation Society. Both organisations advocated Resolution Island in Dusky Sound as a safe national sanctuary for flightless birds. It was proclaimed a reserve in 1891 and the position of curator seemed a logical step for Henry, now middle-aged and in indifferent health. Unfortunately, delays caused by sectional infighting in the growing conservation movement led him to become so depressed that he settled his affairs and made his way to Auckland. Unable to convince scientists of the correctness of his views about the kakapo, his depression deepened and he attempted to shoot himself.
In spite of these problems, in 1894 Henry, with Melland's assistance, was appointed curator and caretaker of Resolution Island. In July he and an assistant, Andrew Burt, were landed on neighbouring Pigeon Island, chosen as their base because of its two usable harbours. They had with them timber for housing supplies and Henry's boat, Putangi; they built a house, store and boatshed. Henry is thought to have moved some 750 ground birds to island sanctuaries within the area of Dusky Sound and prepared a further 100 for shipping to reserves, government departments, botanical gardens, exhibitions and private keepers. Often working alone and in wet, windy field conditions, he pioneered capture techniques, experimenting with dogs and nets. He also proved that with the right conditions birds could survive relocation.
After four years of concentrated work Henry focused on monitoring progress, relocating as necessary. He also devoted almost two years to the search for the takahe. By August 1900 he had become depressed about the threat posed by stoats to the island's birds. He devoted less time to actively relocating birds and more to passive custodianship of the reserves. He wrote articles for the press and the Transactions and Proceedings of the New Zealand Institute, and published a book, The habits of the flightless birds of New Zealand (1903). He reported regularly on his work to the commissioner of Crown lands in Dunedin, and was later transferred from the Department of Lands and Survey to the Department of Tourist and Health Resorts.
In July 1908 Henry was appointed ranger at Kapiti Island, where he stayed until 1911. He retired to Katikati in 1912, moving to Helensville in 1922. He died in the Auckland Mental Hospital at Avondale on 13 November 1929.