Six captive-bred white-shouldered ibises, recognized among the rarest birds on earth, have been released into the wild in northeastern Cambodia, according to the Angkor Centre for Conservation of Biodiversity (ACCB). Conservationists confirmed the milestone on September 19, marking what organizations describe as the first reintroduction effort of its kind for the critically endangered species.
Siem Pang Wildlife Sanctuary Chosen as Release Site
The three male and three female birds, hatched at the ACCB between 2023 and 2025, entered the wild inside the Siem Pang Wildlife Sanctuary. According to the ACCB, the sanctuary serves as the most suitable habitat and represents one of the final remaining strongholds for the species, hosting Cambodia’s largest known wild population.
Cambodia currently supports nearly the entire global population of the white-shouldered ibis, with total estimates remaining below 1,000 individuals. The International Union for Conservation of Nature (IUCN) lists the forest-dwelling bird as critically endangered on its Red List due to severe habitat loss.
Rigorous Health and Behavioral Screening
Prior to release, ACCB specialists evaluated each candidate’s age, physical health, and behavior. Teams monitored flight capabilities, foraging skills, social interactions, and natural wariness toward humans.
"The selection initial des six oiseaux reposait sur plusieurs facteurs, notamment leur âge, leur comportement et leur état de santé," stated Amber Flewitt, ex-situ conservation manager at the ACCB.
Before entering the open sanctuary, the birds spent four weeks inside a soft-release enclosure to acclimatize. Four of the six individuals now carry solar-powered GPS tracking tags, costing approximately $1,000 each, to allow researchers to monitor post-release movements.
Long-Term Monitoring and Protection Plans
According to Jack Willis, in-situ conservation and research manager at the ACCB, the newly freed birds remained close to the release site during their initial adaptation phase. The ACCB and conservation partner Rising Phoenix will track the flock and protect local nesting and roosting locations.
Habitat destruction remains the primary threat to the species, which relies heavily on large trees for roosting and seasonal forest pools, known as trapeangs, for feeding. The current program evaluates survival rates and the return of natural behaviors, such as colony resting.
"Ce relâcher nous donne la possibilité d’apprendre et de corriger d’éventuels problèmes imprévus," Willis noted.
Future Expansion of the Conservation Program
The ACCB currently houses 18 white-shouldered ibises at its facility, with eight individuals identified as potential candidates for future releases pending health and behavioral assessments. Conservationists aim to conduct subsequent releases annually, supported by three active breeding pairs.
The initial reintroduction received technical and financial backing from the Cambodian Ministry of Environment, the Ministry of Agriculture, Forestry and Fisheries, alongside international donors including the Zlín Zoo in the Czech Republic.