Species richness, population, sex ratio and activities of hornbills inhabiting patches of forests in an oil palm plantation concession in Penajam Paser Utara, East Kalimantan

Well-maintained oil palm concessions with patches of natural ecosystems can be a home for Hornbills. This paper is mainly focused to evaluate the species richness and activities of the hornbill community inhabiting patches of forest in oil palm plantations in Penajam Paser Utara, East Kalimantan. The ecological observation was focused on the largest forest patches, a total of 1 432 Ha. The data collected included species inventory and behavioral activities of hornbills. Hornbill activities were observed from 45 observation stations using the fixed radius point count method. Vegetation data were collected using a single plot method in 52 stations. Based on the vegetation survey, the number of plant species found was 151 species from 53 plant families. Dominant families are Moraceae and Euphorbiaceae with 14 species. The forest patches are used for foraging sites by hornbills, they fed on Ficus benjamina (Moraceae) and Ficus sp. (Moraceae). The favorite tree for roosting is Kompasia excelsa because the tree is around the Ficus benjamina and is an Emergent tree. Our results show that remnants of forest patches on oil palm plantations can provide spaces for hornbills' activities which supports the sustainability of hornbills in the region.