A growing number of red-headed Sarus cranes are reportedly flocking west from Vietnam to a protected sanctuary in Kampot province’s Kampong Trach district, and conservationists observing the trend aren’t sure why.

The Tuoitrenews website reported on Saturday that unusually large numbers of the birds, which are classified as vulnerable to extinction, have left their well-known flapping grounds in Vietnam’s southwestern Kien Giang province for the Kingdom’s wetlands.

Hundreds have flocked to the 217-hectare Anlung Pring sanctuary, the report said, referring to the name for the preserve in Kampong Trach district where the cranes have been known to nest in smaller numbers from November to May before flying to Ang Trapeng Thmor Reserve in Banteay Meanchey province, about 100 kilometres from Siem Reap.

Mere kilometres from the Vietnamese border, Anlung Pring was declared a protected wetland area in 2006, making hunting wildlife there illegal.

Sarus cranes frequently make short seasonal trips between dry and wet season habitats in Southeast Asia and Australia, according to the International Crane Foundation. But better data are needed to understand why more of the cranes than usual are coming to Cambodia, Bou Vorsak, BirdLife International country program manager, said.

“Since February 14, we have counted 310 cranes in the area, which is an increase when compared to previous years,” Vorsak said.

“Part of the success that could explain the increase in population in Anlung Pring Sanctuary is that BirdLife has been working to educate the community about the importance of protecting the cranes,” he said. “We haven’t received any reports about people hunting in the sanctuary for the last three years.”

Hong Chamnan, a project manager for Wildlife Conservation Society, said yesterday that about 859 Sarus cranes were found living throughout all of Cambodia in 2013.

“About 1,500 of the cranes live in Cambodia, Myanmar and Vietnam,” Chamnan said, adding that the population has decreased in the past 50 years due to hunting, pollution and the conversion of wetlands for agricultural use.