Slimbridge Wildlife and Wetlands Trust (WWT) has issued a heartfelt tribute after the loss of a key colleague whose death triggered global praise for his contribution to bird conservation.

Richard Hearn, who lived in Stroud, began his career with the WWT in 1993 and rose to become an internationally recognised figure in pioneering research for endangered birds.

A statement from the Trust said Richard, had "lost his battle with illness and has sadly passed away", adding that the staff's thoughts are with his family and friends."

Richard was 54 and leaves a partner, Becca.

The statement added: "The waterbird world will be a different place going forwards without Rich Hearn, he leaves a huge hole and will be desperately missed. Rich will be known to many for he has been instrumental not only in the monitoring and research of wildfowl species in the UK and Europe, indeed he has worldwide, too.

"Rich started his career at the Wildfowl & Wetlands Trust (WWT) back in 1993, when the Trust hired him to plan an expedition to Argentina to search for Brazilian Merganser, in which he participated from June to October that year.

"This expedition sparked Rich's interest in studying wildfowl and on returning, he went on to work on non-native Ruddy Ducks (in the UK) and Pink-footed Geese (in the UK and Iceland). In 1995, Rich took on a full-time post as a Bird Ringing Assistant, coordinating WWT's bird capture and ringing activities, along with working closely with UK bird ringers to increase capture and marking effort."

As the Trust's Head of Species Monitoring, Rich went on to work on a range of mostly international waterbird conservation projects, including numerous population monitoring and assessment projects, while he also led the UK's Goose & Swan Monitoring Programme for several years.

 Kane Brides, senior research officer, told Punchline-Gloucester.com: "Rich also worked on species action planning and recovery for Baer's Pochard and Long-tailed Duck, avian influenza surveillance, capacity building for waterbird monitoring in the African-Eurasian and East Asian flyways, and other issues such as sustainable hunting and goose-agriculture conflict."

Richard's research took him to Iceland for work on Pink-footed Geese and Whooper Swans, to Russia, to ring Bewick's Swans, Bulgaria (Red-breasted Geese), China (Spoon-billed Sandpipers and Baer's Pochard), Bangladesh, Kuwait, Dubai and Nigeria, while he also became a seasoned figure on the international conferences circuit.

More recently, he worked in policy and advocacy, focussing on international issues.

Mr Kanes added: "This involved closely working with WWT teams to secure changes to policy, strategy and legislation among key international stakeholders, including multilateral environmental agreements such as the Ramsar Convention on Wetlands, the East-Asian Australasian Flyway Partnership and the African-Eurasian Migratory Waterbird Agreement.

"His passion for birds, especially waterbirds and their monitoring, status and conservation was infectious. He was always kind with his time and knowledge and always keen to pass this on to younger scientists. As the Global Chair of the IUCN's SSC Duck Specialist Group, he provided strong and sustained promotion to the Pan-European Duck Symposia, with a particular support to students and young scientists. We all owe him a lot.

Professor Ding Changqing of Beijing Forestry University said: There seemed no end to the sheer number of people whose lives Rich has touched from all corners of the of the world and every level of seniority. He was clearly held in such high esteem by so very many. His charming, easy personality, and his generous giving of his expertise without show or ego, made him one of the greatest waterbird conservationists I have had the privilege of knowing."

Online reaction reflected a tide of praise for Richard. Adele Masztalerz wrote: "Wonderful tributes from his colleagues for a brilliant conservationist and all-round good egg."