Jonathan was amongst the first international conservationists to work in Vietnam and first visited the country in 1988. As the political climate became relaxed and donor interest increased he became progressively more involved in developing BirdLife's conservation activities in-country. He moved to Vietnam in 1993, first on secondment to WWF working on the Biodiversity Action Plan, and then opening a representative office for BirdLife and developing a portfolio of conservation projects. Early project interventions were focused on conducting status assessments for threatened species and sites, and later shifted to protected area establishment, which has remained the focus of the programme. Since its start, BirdLife Vietnam Programme has conducted biodiversity assessments of the Red River and Mekong Deltas, secured the gazettement of numerous new protected areas, undertaken a gap analysis of the protected areas system, and published the first Vietnamese-language field guide to the birds of Vietnam.

Jonathan has a strong interest in ornithological exploration which was kindled through his museum training, and has resulted in the discovery and description of three bird species and numerous subspecies new to science, as a result of expeditions to the remoter parts of Vietnam's Central Highlands. In 2000, he participated in the first ornithological exploration of the Cardamom Mountains in Cambodia. He publishes regularly on bird taxonomy and distribution. Jonathan has worked for BirdLife International for 10 years and has seen the organisation evolve and become a force in international conservation. Prior to joining BirdLife, Jonathan worked in reserve management at Strumpshaw Fen Nature Reserve in Norfolk, UK, and earlier worked for the British Trust for Ornithology. He has a B.A. in Development Studies from the University of East Anglia, U.K.