“I recorded 15 nests on the beach, smaller numbers compared with previous years,” says Ratchaneekorn Buaroey, a member of the Bueng Kan Rak Nok conservation group, who observed the chick in February. “I have serious concerns about the declining numbers of [small pratincoles and little ringed plovers].”
Small pratincoles (Glareola lactea) mate for life and, like other vulnerable birds on the Mekong, lay their eggs in the sands of the October–May dry season. In recent years, hydropower dams have contributed to unseasonable water levels. In the dry season this has included both abnormally low water levels and flooding, says Ratchaneekorn.
She and her husband, Noppadol Buaroey, have been monitoring the birdlife of Bueng Kan for 12 years, noting the eggs of beach-nesting birds on the banks of the Mekong.
In 2018, nests holding 21 bird eggs were flooded, more than half the active eggs Bueng Kan Rak Nok recorded in the area. The same has not happened this year, as the 2021 dry season has been very dry, says Ratchaneekorn.
“These birds require several months of low water to incubate their eggs and rear their chicks. With the unseasonal water levels, the nests are unpredictably flooded,” says Ayuwat Jearwattanakanok from the Bird Conservation Society of Thailand. “The river needs to be dry during the right season, and flooded during the right season. Otherwise, species that have relied on such seasonal rhythms for centuries will gradually go extinct.”
There are 12 operational mainstream Mekong dams upstream of Bueng Kan, 11 in China and one in Laos, and more mainstream dams are in various stages of planning and development in Laos.
“Sudden releases of water from Chinese dams during the dry season have rendered the Mekong almost unrecognisable from the river it once was,” says Phil Round, regional representative of the Wetland Trust and research associate at Michigan State University Museum. “Many eggs and small, still flightless young are washed out and destroyed.”
The 2021 dry season has been unpredictable, largely driven by the maintenance and testing of China’s Jinghong dam site close to the Thai and Laos borders.
According to data from the Stimson Center, a Washington DC-based think-tank, levels below the Jinghong have been spiking up and down since December because of hydropeaking operations. This is when turbines are shut off overnight, restricting water release until demand spikes the next day. Brian Eyler of the Stimson Center says the Jinghong hydropower plant is responding to local energy demand in Yunnan’s Xishuangbanna prefecture.
The principal affected species along Thai stretches of the Mekong are small pratincoles, of which there may be fewer than 1,000 pairs, and river lapwings, with perhaps fewer than 100 pairs, Round says, adding that the little ringed plover and red-wattled lapwing are similarly affected.