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Abstract. Agusan marsh is one of the most ecologically significant wetland ecosystems in the Philippines. Sago, terminalia, mixed swamp, and peat swamp forests in Agusan Marsh were surveyed from August 2005 to January 2006 using a combination of mist netting (3,337 net days) and transect walk methods to determine the distribution, endemicity, and conservation of birds in Agusan marsh. One hundred twenty-four species of birds were identified with low endemism of 25%. The mixed swamp forest had the highest species richness (S = 92) while sago forest had the least (S = 70). Peat swamp forest had the highest number of migratory birds (S = 26). Highest endemicity was recorded in the terminalia forest (21%). Migratory birds were recorded at the start of sampling in August and considerably increased thereafter reaching its peak in November. A sudden decline in the number of endemic species was observed in November. Forty-six species of birds which include six migratory species were reported to be of socio-economic importance. Changes in the structural and floristic composition brought about by forest degradation such as conversion of forest into agriculture, timber poaching and hunting were seen as threats to the birds in Agusan marsh. Conservation of the different habitats in the marsh is necessary for the retention of the broadest avifaunal diversity.
Key Words: distribution, endemicity, migratory, peat swamp, wetland.
Introduction. The Philippines has 576 birds species, 195 of which are endemic and 74 (12.8%) of which are threatened with global extinction (Gomez et al 2009). The latest report is a higher count of more than 600 bird species (Birdwatch.ph 2012). Birds are considered the most important indicator of changes in ecosystem balance in nature because of their highly specific habitat requirements (Prakash & Manasvini 2013).
The Agusan Marsh is a protected area, officially called the Agusan Marsh Wildlife Sanctuary (AMWS). It stores more than 15% of the freshwater resources in the Philippines (Almeria & Nuñeza 2013). Mallari et al (2001) reported that several threatened species have been recorded in or near Agusan Marsh in the past, mainly forest birds, but it is unclear whether they have significant populations in the remaining forests. However, Alcedo argentata (Silvery Kingfisher) was recently recorded in the marsh itself. The marsh is also home for...