Ronald Mathias Lockley was born in 1903 in Cardiff. In 1927 he obtained a lease for the island of Skokholm, a 240-acre island off the coast of Pembrokeshire, where he made a living from the rabbits and farming. He also wrote articles for the magazine The Countryman, scientific papers, novels on Pembrokeshire life and factual books on island life and its wildlife. He continued to write prolifically throughout his life.

In 1933 he established the first bird observatory in Britain on Skokholm, and in 1934 he co-directed with Julian Huxley the filming of a documentary, The Private Life of the Gannet, on the island of Grassholm, which later won an Oscar for best documentary. In 1938 he helped found the Pembrokeshire Bird Protection Society, which became the West Wales Field Society and then the Wildlife Trust. He also visited a number of islands in the 1930s, including Bardsey, Fair Isle, North Ronaldsay, Heligoland, the Blaskets, Faeroe, the Westman islands, Berlengas, Madeira, the Desertas and Selvagens.

In 1940, Lockley and his family were forced to leave Skokholm for mainland Pembrokeshire. He spent the war years farming in North Pembrokeshire and for a time was involved in naval intelligence operations surveying beaches. After the war he remained in mainland Pembrokeshire and in 1946 established a field centre on the island of Skomer. In 1953 he investigated the outbreak of myxomatosis in rabbits for the Nature Conservancy. He also studied the behaviour of rabbits at his home in Orielton, Pembrokeshire. In 1955 he became the founding editor of Nature in Wales and served as editor until 1970. He also served on the National Parks Commission and the Pembrokeshire National Parks Committee. He moved to Devon in 1964 and then emigrated to New Zealand in 1977. In New Zealand he helped establish the Miranda Naturalists' Trust and New Zealand's first bird observatory. He was awarded an honorary MSc from the University College of Wales, Aberystwyth, in 1977, and the British Ornithologists' Union medal in 1993. He died in New Zealand in 2000.

Biographical notes written with reference to 'Ronald Mathias Lockley (1903-2000)', Ibis, vol. 143, 2001, pp. 167-168, and 'Lockley, Ronald Mathias (1903-2000)', Oxford Dictionary of National Biography, both written by David Saunders.