Leoffn Beresford Mouritz, the son of Henry Joseph Mouritz of Chicago, USA, was a prospector, stockman and ornithologist. He did a good deal of ornithological work in England, especially in and around London. Most of his earlier observations were made in Richmond Park, near his home on the west side of London, and at the age of seventeen he published an article in the Zoologist on the birds of the neighbourhood. After extending his observations to particularly the moorlands in the south-western part of Surrey he decided, with several other ornithologists, to publish an annual report on the birds of Surrey in the Zoologist. The first of these reports appeared in 1907. However, the work was discontinued when he left for Southern Rhodesia (now Zimbabwe) later that year.
Mouritz compiled 'Ornithological notes from the south-western border of Rhodesia', a paper that was presented on his behalf by E.C. Chubb* before the Rhodesia Scientific Association in Bulawayo in June 1910 and published in the association's Proceedings (1910). It presented an annotated list with breeding notes. His next paper, 'Notes on Euplectes xanthomelas, Ruepp' was a study of the Yellow-rumped Wydah in Zimbabwe and appeared in the Journal of the South African Ornithologists' Union (1913). From August to December 1911 Mouritz prospected in south-eastern Katanga, Belgian Congo (now the Democratic Republic of the Congo). His notes on birds observed in Katanga were published in The Ibis (1914). During 1912 he was again in Zimbabwe. His comprehensive 'Notes on the ornithology of the Matopo District' (a total of 70 pages) was published in The Ibis (1915), in two parts, in the form of an annotated list. He was a careful and well-informed observer and collector, but the whereabouts of the material he collected is unknown.
When Mouritz left Zimbabwe he first returned to England and then proceeded to Australia, where he worked as a stockman at Dalby, Queensland. In September 1914, following the outbreak of World War I (1914-1918), he joined the Australian Army as a private in the Second Light Horse Regiment, embarked in Brisbane that same month, and was killed in the battle on the Gallipoli Peninsula, Turkey, the next year.
Mouritz became a member of the British Ornithologists' Union in 1912 and was also a member of the South African Ornithologists' Union. He was not married.