Lake Lanao is the second largest lake in the Philippines and the largest in Mindanao. It is a large, oligotrophic, freshwater lake, formed by the tectonic volcanic damming of a basin between two mountain ranges and the collapse of a large volcano. This IBA includes the lake itself and some extensive forest cover on its south and southeast shorelines. Some of the higher altitude forests of the Lake Lanao Watershed are included in the Butig Mountains (PH099) and Mt Piagayungan (PH098). There are extensive reed beds around the edges of the lake, and large areas of Eichhornia crassipes and other aquatic vegetation on the lake surface. Most of the surrounding areas have been cleared for agriculture but there is still some primary lowland dipterocarp forest on the nearby Sacred Mountain, and there are patches of secondary dipterocarp forest at Wao. The lake serves as a reservoir for the generation of hydroelectric power on the Agus River, which generates 70% of the electricity used by the people of Mindanao. It supports a major fishery, and is important for recreational activities including boating, swimming and sport fishing. There are several towns and many villages around it, and a Mindanao State University campus is situated there.
Several of the threatened and restricted-range species of the Mindanao and Eastern Visayas Endemic Bird Area have been recorded around Lake Lanao, all forest birds apart from Spot-billed Pelican and Philippine Duck. The pelican is extinct there, but Philippine Duck probably still occurs, as the lake is reported to support large numbers of waterfowl. It is likely that some of the old bird records from ‘near Lake Lanao’ were actually collected in, for example, the nearby Mt. Piagayungan (PH098) or the Butig Mountains (PH099). However, the limited area of lowland forest near the lake could still support some forest birds.
Non-bird biodiversity: Lake Lanao is of great limnological interest. The fauna includes many species of fishes and invertebrates that are endemic to the lake, and presents an outstanding opportunity for research on evolution in the Cyprinids. There are about twenty species of Cyprinidae endemic to the lake, but many of the other fishes occurring in the lake have been introduced.. Mammals occurring in the area include wild pig (probably Sus philippensis) and deer Cervus mariannus and many endemic small mammals.
BirdLife International (2021) Important Bird Areas factsheet: Lake Lanao. Downloaded from http://www.birdlife.org on 02/03/2021.