The Duke of Edinburgh first became interested in bird-watching in 1956 while travelling in HM Yacht Britannia across the southern Pacific Ocean between New Zealand and the Antarctic continent.
He began to look at the seabirds, to put names to them and to take photographs. The journey continued through the South Atlantic with more opportunities to take photographs of the birds on the various islands visited and at sea.
A second long voyage in 1959 across the Central Pacific provided him with the chance to take photographs of the best-known tropical seabirds on Christmas Island, which was then being used to test nuclear devices.
Opportunities for bird-watching and photography were sometimes available during breaks in official visits to Iceland, South America, Canada and other countries, particularly in Africa.
While on a visit to Australia in 1963, His Royal Highness got up early one morning to watch birds at Pelican Point on the Swan River.
He visited Hilbre Island off West Kirby in Cheshire in 1965 and in 1969 he paid bird-watching visits to lakes in Ethiopia and Lake Rudolf in Northern Kenya. He first visited the Galapagos Islands in 1964 and toured the Okavango Delta in Botswana in 1996 as President of WWF.
The Duke of Edinburgh was President of the British Trust for Ornithology from 1987.