Avian species diversity in oil palm plantations of Agusan Del Sur and Compostela Valley, Philippines

Oil palm trees have become the most expanding equatorial crops in the world and their product, palm oil, is produced, traded and used more than any other vegetable oil worldwide. The expansion of oil palm cultivation, however, is frequently cited as a major factor causing deforestation that may result in biodiversity losses in tropical countries. In this study, an assessment of the avifauna in oil palm plantations in Agusan del Sur and Compostela Valley, Mindanao, Philippines was done from April 2010 to July 2010. Sampling sites were categorized based on the age/growth of palm trees. Line transect method, mist netting and birdwatching were used to gather data on avifauna. Eighty-eight species were recorded. Species richness, abundance, and number of endemic species were also recorded to be higher in mature plantations than in young plantations. A significant difference was noted in bird abundance found in the different age groups of oil palm plantations in Agusan del Sur. Thirty-one endemic species were recorded, one of which is Mindanao endemic. Three vulnerable species, Gallicolumba criniger (Mindanao bleeding-heart), Alcedo argentata (silvery kingfisher) and Ficedula basilanica (little slaty flycatcher) were recorded both in the young and mature plantations. The Aethopyga primigenius (grey-hooded sunbird), a near threatened species was recorded in mature plantations only. The presence of these vulnerable species in all study sites indicates the need to protect the degraded secondary residual forest and forest patches along the plantation. Introduction. Oil palm, Elaeis guineensis Jacq., is a tropical plant that originally came from the Gulf of Guinea in West Africa and frequently planted on newly-cleared rainforests or peat-swamp forests rather than on already degraded land or disused agricultural land. Its main product is palm oil, which is commonly used as cooking oil, shortening, margarine, soap, detergents, pharmaceutical products, cosmetics and fuel (Basiron 2002; Brown & Jacobson 2005). About 43 countries are presently cultivating this agricultural crop in a total area that is nearly one-tenth of the world's permanent cropland (FAO 2000; Basiron 2007). Indonesia and Malaysia are the world's principal producers for palm oil accounting for 83 percent of production and 89 percent of global exports. Oil palm plantations in Indonesia have grown to 3,107,985.73 ha and in Malaysia, 3,496,483.95 ha (Brown & Jacobson 2005). It is projected that additional land will be developed from 1 to 28 M ha in Indonesia and 0.06 to 5 M ha in Malaysia in order to meet the demand for palm oil production in 2020. This demand can be met to a large extent when only degraded land may be used and if no further deforestation is assumed (Wicke et al 2010). In the Philippines, 65,000 ha of land situated in CARAGA, and Region 12 in Mindanao and Central Visayas are currently planted with oil palm trees. Production increased from 54,000 T in 2000 to 92,000 in 2010, but the production increase from 2009 to 2010 is very low probably because of the low yield of the aging palm trees. Other plantations in the Philippines are relatively young and they are producing low quality of palm oil. It is to be noted that the domestic demand for oil palm in the country