Legge was elected the founding President of the RAOU in 1901 and served various offices within it, notably on the Check-list Committee, until his death. He was also a Colonial Member of the British Ornithologists' Union, an Honorary Fellow of the American Ornithologists' Union, a fellow of the Royal Geographical Society and a member of the Zoological Society of London, the Linnean Society. He was also a founder and president of the Royal Australasian Ornithologists Union and vice-president of the Royal Society of Tasmania. The highest point on the Ben Lomond plateau is named Legges Tor to honour his survey of the region.