Danum Valley is very popular with bird-watchers from around the world, who come here to bag a whole variety of Southeast Asian rainforest species, including the great argus pheasant, crested fireback pheasant, several species of hornbill, blue-headed pitta and Borneo bristlehead, among many others. Some of the guides at the lodge are particularly knowledgeable about birds and attempts are made to match birders up with these guides.
The access road and canopy walkway are good for early morning bird sightings and you'll likely make a few worthwhile sightings right from the veranda of your cabin.
