Chester Zoo scientists are testing a novel tail-tagging technique to help reintroduce rare pheasants to the wild.
Conservationists at Chester Zoo recently trialled attaching dummy transmitters to the tail feathers of three Vietnam pheasants in their care. This crucial step is part of a global effort to reintroduce the critically endangered species back into the wild.
Vietnam pheasants (Lophura edwardsi) have not been seen in their natural habitat for 25 years, and in 2024, the IUCN designated them as “probably extinct in the wild.” The birds, once native to the dense forests of central Vietnam, have been decimated by logging, poaching, habitat loss, and environmental damage caused by chemicals used during the Vietnam War. Now, a collaborative international project is working to restore their population in the wild, with Chester Zoo playing a key role.
The project, led on the ground by Viet Nature, is supported by a range of partners, including Conservation Vietnam, Mandai Nature, Keidanren Nature Conservation Fund, and the World Pheasant Association. Chester Zoo’s work focuses on ensuring that birds bred for release can be effectively monitored post-release — a critical element in evaluating the success of reintroduction efforts.
Leah Williams, Lead Conservation Scientist: Population Biology at Chester Zoo, explained:
“Our ultimate goal is to breed Vietnam pheasants for release, but we need to be certain they can survive in the wild. Post-release monitoring is essential, and that’s where these transmitters come in. Before using them in the wild, we need to make sure they work with this species. They’re commonly used with birds of prey, but they’ve never been tested on Vietnam pheasants before. We’ve established a baseline of the pheasants’ behaviour at the zoo so we can compare how they respond with the transmitters attached.”
The transmitters, weighing just 6g, are attached to the tail feathers using small crimps. The aim is for the transmitters to stay in place until the feathers naturally moult, allowing the devices to be retrieved for data collection. This process will provide critical insights into how the transmitters affect the birds’ behaviour and how long they remain in place.
This part of the project builds on work previously carried out by ZSL (Zoological Society of London), where similar devices were fitted to Vietnam pheasants at Whipsnade Zoo and London Zoo. Chester Zoo’s bird team collaborated with London Zoo staff during the tail tagging process to ensure best practices.
The data gathered through these trials will inform how to attach real Very High Frequency (VHF) transmitters to birds destined for release. VHF technology is being used over GPS transmitters because GPS signals may struggle to penetrate the dense forest canopy where the pheasants will be reintroduced. Monitoring released birds in such environments presents significant challenges — the transmitters must be lightweight yet powerful enough to send signals through thick vegetation.
Andrew Owen, Head of Birds at Chester Zoo, highlighted the importance of this work:
“If the tail tagging trials go well, we can apply this technique at Viet Nature’s conservation breeding centre in Le Thuy, where Vietnam pheasants are prepared for release. Birds there are housed in training aviaries that allow them to develop social and foraging behaviours before they return to the wild. The pheasants at Le Thuy are bred from birds that are part of the EAZA ex-situ conservation-breeding programme (EEP), where zoos like Chester, London, and Whipsnade play a crucial role. Pairs are carefully selected to ensure that chicks are as genetically diverse and healthy as possible, giving them the best chance of thriving once released.”
The longer-term reintroduction strategy involves much more than just breeding and releasing birds. It includes ongoing efforts to remove snares from selected habitats, engage with local trappers, and refine the in-country breeding programme to ensure that the birds are well-prepared for survival in the wild. If successful, the descendants of Vietnam pheasants currently cared for in European and Asian zoos could one day populate their ancestral forests in Vietnam.
Males of the species are striking, with dark blue, iridescent feathers, a short white crest, and distinctive red caruncles around their eyes. Females have rich brown plumage that blends with the forest floor. Visitors to Chester Zoo can find the pheasants in an aviary near the chimpanzee habitat and another close to the snow leopard enclosure.
This tail-tagging trial is a small but significant step toward a much larger goal: ensuring that future generations of Vietnam pheasants can reclaim their place in the wild, safeguarding the survival of this magnificent species.
Project Partners Include:
BirdLife International, Conservation Vietnam, Viet Nature, Critical Ecosystem Partnership Fund, Keidanren Nature Conservation Fund, IUCN Netherlands, World Pheasant Association, Mandai Nature, Stiftung Artenschutz, Wingham Wildlife Park UK, World Land Trust, KNCF, Karlsruhe Zoo, Paignton Zoo, Prague Zoo, VINACONSERV, WPA, Zoo and Tierpark Berlin, Zoological Society of London, Antwerp Zoo, and Chester Zoo.