During construction, the Welsh Harp attracted uncommon birds. James Edmund Harting and Frederick Bond were regular visitors and shot many birds. Harting documented these in his 1866 book the Birds of Middlesex. They included rare vagrants to the UK such as little bittern, squacco heron and white-rumped sandpiper. This started an interest in the birds of the Welsh Harp that continues until today, giving a unique historical perspective of a site in London. The next prominent ornithologist was William Glegg from the 1920s onwards and he wrote a paper for the London Naturalist in 1930 called 'The Birds of Middlesex since 1866, then a follow-up book to Harting's in 1935, called A History of the Birds of Middlesex. After the Second World War, a new generation of ornithologists took an interest, such as Professor Warmington, and Eric Simms, who lived just south of the reservoir in Dollis Hill. They were joined by Dr Leo Batten in the late 1950s. He was one of the movers in setting up the Welsh Harp Conservation Group (WHCG) in 1972 to fight off development. The WHCG has worked to protect the area as a nature reserve, including preventing a golf course and driving range from being built.