Charles Bethune Horsbrugh was the younger son of Captain Charles Bell Horsbrugh of the Second Central India Horse Regiment. His older brother Boyd R. Horsbrugh* also lived in South Africa for some time and the two have sometimes been confused. Charles published a paper on "Occurrence of the Night Heron in County Cork" in The Irish Naturalist in 1896. He came to South Africa in June 1905 and joined his brother in Bloemfontein, where they studied and collected birds together. The next year he contributed "Some observations upon the behaviour and treatment in captivity of Otis caerulescens (Blue Korhaan)" to the Journal of the South African Ornithologists' Union (Vol. 2(1), pp. 29-31). In December 1905 he was appointed as clerk at the Transvaal Museum, now the Ditsong National Museum of Natural History. He presented the museum with Lepidoptera from the Pretoria district during 1906/7, but had left by the middle of 1907. He returned to England in August 1907 with a large collection of South African birds.
In 1915 Horsbrugh resided in Alberta, Canada, and published two notes on the birds he observed at Alix, Buffalo Lake and Red Deer during 1915-1916 in The Ibis (1915, 1918). He settled at Red Deer in October 1915 and maintained an interest in ornithology for the rest of his life.