The rare birds were released in Lampang’s Chae Son National Park on Thursday by the Zoological Park Organization (ZPO).
The two released birds are among several large hornbills bred and studied in artificial habitats.
“Researchers will continue to study 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 complete our study before deciding where the next pair will be released.”
He said the great hornbills were an endangered species and could only be found in certain parts of Thailand. No great hornbills have been sighted in the North for the past 20 years.
Great hornbills are the largest of this species and can measure from 95 to 120 centimeters in length with a wingspan of 150 to 178 cm and weigh up to 4 kilos.
Atthaporn said the breeding project started in 1997, with the first great hornbill hatching five years later.
This project is a collaboration between ZPO, six northern national parks, Kasetsart and Mahidol universities and private partners.
The birds are raised in a natural environment and trained to survive in the wild.
Greater hornbills are one of 13 species of hornbills found in Thailand, all of which fall under the Wildlife Conservation and Protection Act 2019. The species is also listed on the International Union for Conservation of Nature’s “Red List” of Threatened Species.