Bhutan is a paradise for bird lovers and ornithologists. These include ducks, waders, birds of prey, thrushes, finches and buntings. The partial migrants to Bhutan include cuckoos, swifts, bee-eaters, warblers and flycatchers. The country harbors more than 16 species of vulnerable birds. They are the Pallas’s Fish Eagle, White bellied Heron, Satyr Tragopan, Gray-bellied Tragopan, Ward’s Trogon, Blyth’s King Fisher, Yellow-rumped Honey Guide, Rufous Throated Wren Babbler, Chestnut-breasted Partridge, Blyth’s Trogon, Wood Snipe, Dark-rumped Swift, Rufous-necked Hornbill, Gray-crowned Prinia and the Beautiful Nuthatch all of which breed in Bhutan. Bhutan is home to many species of birds that are in danger of extinction, including the Imperial Heron, which is one of the fifty rarest birds in the world and the rare Black-Necked Crane, which breeds in Tibet and then migrates over the Himalayas to Bhutan during the winter months. The Cranes can be spotted in Phobjikha Valley in Western Bhutan, Bumthang in Central Bhutan and in Bumdeling in Eastern Bhutan. They migrate to these winter roosting sites in the months of September and October and fly back to Tibet between February and March.