The rare birds were released on Thursday in Lampang’s Chae Son National Park by the Zoological Park Organisation (ZPO).
The two released birds are among several great hornbills being raised and studied in artificial habitats.
“Researchers will continue studying the released birds to see how they nest, how they survive and raise their young,” ZPO director Atthaporn Sriheran said. “We will then use this data to supplement our study before deciding where the next pair will be released.”
He said great hornbills were an endangered species and can only be found in certain parts of Thailand. No great hornbills have been sighted in the North over the past 20 years.
Great hornbills are the largest of this species and can grow 95 to 120 centimetres long with a wingspan of 150cm to 178cm and can weigh up to 4 kilos.
Atthaporn said the breeding project kicked off in 1997 with the first great hornbill being hatched five years later.
This project is a collaboration between ZPO, six national parks in the North, Kasetsart and Mahidol universities as well as private partners.
The birds are being bred in natural surroundings and trained to survive in the wild.
Great hornbills are one of the 13 species of hornbills found in Thailand, all of which come under the 2019 Wild Animal Conservation and Protection Act. The species is also included in the International Union for Conservation of Nature’s “Red List” of Threatened Species.