The IBA comprises Dayan Lake, the smaller Khar Lake to the southwest, and the area surrounding these two lakes. About 10 small rivers and springs flow into the lake, and only the Khatan River flows out, later merging into the Khovd River. The lake is frozen from October to June. There is emergent vegetation along some stretches of the lake shore. The site is considered to have great potential for ecotourism but this has not yet been developed. The beautiful Mongol Altai mountains with their forests, snow-capped peaks and glaciers can be seen from the lake shore. Areas with tall grass and reeds are often heavily grazed by livestock, which also cause disturbance to breeding waterbirds. In recent years, the water level has dropped due to drought.
Three Globally Threatened species occur in significant numbers: Saker Falcon Falco cherrug (EN); Lesser Kestrel Falco naumanni (VU); and White-throated Bushchat Saxicola insignis (VU, breeding). The site also supports assemblages of species restricted to the Eurasian steppe and desert and Eurasian high montane biomes. In addition, the site supports a population of Mongolian Accentor Prunella koslowi, whose breeding range defines the Mongolian Mountains Secondary Area. The site regularly supports at least 1% of the flyway populations of Bar-headed Goose Anser indicus, Ruddy Shelduck Tadorna ferruginea and Northern Lapwing Vanellus vanellus, which occur in large numbers in autumn.
Non-bird biodiversity: Grey Wolf Canis lupus, Red Fox Vulpes vulpes and Pallas's Cat Felis manul all occur at the site.
BirdLife International (2020) Important Bird Areas factsheet: Dayan Lake. Downloaded from http://www.birdlife.org on 28/09/2020.