Agusan Marsh is the biggest marshland in Asia in terms of
area which is 19, 196.558 hectares. It is the wintering
ground of the migratory water and wetland birds from the
South East Asia Region. It is the host to a wide array of
rare threatened and endangered species and is considered the
most significant wetland in the Philippines.
Agusan Marsh is found in the middle of the Agusan River Basin which is the third largest river basin in the country. The municipalities within the Marsh are San Francisco, Loreto, La Paz, Veruela and Rosario.
There are 33 species of flowering plants in the seven habitat types of Agusan Marsh. A total of 102 birds species were iodentified by the 1991 wetland survey team. Among the endangered bird species found in the area are the oriental darter ( Anhinga melonogaster) and the purple heron (Area purpurea). The marshland is also noted for its high population of wandering whistling ducks (Dendrocygna arcuata). Also common in the area are the small fruit bats and the macaque (Macaca fascicularis). Of reptile and amphibius, two species were identified to dwell in the marshland, namely crocodylus porosus and crocodylus mindorensis. There are also 22 lizard species and seven snake species including the reticulater phyton and the Philippine Cobra (Naja naja).