Ebird describes it as "A medium-sized bird of forest and edge in the mountains on Palawan. Olive-brown above, blending to a more brownish crown which can be slightly raised into a crest, with a yellow belly blending to an olive chest and a whitish throat. Note the pale orange eye. Somewhat similar to Ash-fronted Bulbul, but has yellow belly and pale eyes. Call is a simple nasal “chewp!”[3]The sulphur-bellied bulbul was originally described in the genus Criniger. Some authorities have classified the sulphur-bellied bulbul in the genera Hypsipetes and Ixos. Alternate names for the sulphur-bellied bulbul include the golden-eyed bulbul and olive bulbul. The latter name should not be confused with the species bearing the same name, Iole virescens
Not much is known about its diet but it is presumed to be the typical bulbul diet of fruit and insects. Found single, in pairs or small flocks. [4]
Habitat and conservation status
Its habitat is primary lowland forest, secondary growth and forest edge.
^BirdLife International (2016). "Iole palawanensis". IUCN Red List of Threatened Species. 2016: e.T22713176A94363503. doi:10.2305/IUCN.UK.2016-3.RLTS.T22713176A94363503.en. Retrieved 12 November 2021.
^Fishpool, Lincoln; Tobias, Joseph A. (2020). "Sulphur-bellied Bulbul (Iole palawanensis), version 1.0". Birds of the World. doi:10.2173/bow.subbul1.01species_shared.bow.project_name. ISSN 2771-3105.
^IUCN (2023-05-23). Dicrurus palawanensis: BirdLife International: The IUCN Red List of Threatened Species 2023: e.T232589773A235461135 (Report). International Union for Conservation of Nature. doi:10.2305/iucn.uk.2023-1.rlts.t232589773a235461135.en.
^IUCN (2016-10-01). Iole palawanensis: BirdLife International: The IUCN Red List of Threatened Species 2016: e.T22713176A94363503 (Report). International Union for Conservation of Nature. doi:10.2305/iucn.uk.2016-3.rlts.t22713176a94363503.en.
Gregory, Steven M. (2000): Nomenclature of the Hypsipetes Bulbuls (Pycnonotidae). Forktail16: 164–166. PDF fulltext
Moyle, Robert G. & Marks, Ben D. (2006): Phylogenetic relationships of the bulbuls (Aves: Pycnonotidae) based on mitochondrial and nuclear DNA sequence data. Mol. Phylogenet. Evol.40(3): 687–695. doi:10.1016/j.ympev.2006.04.015 (HTML abstract)
Pasquet, Éric; Han, Lian-Xian; Khobkhet, Obhas & Cibois, Alice (2001): Towards a molecular systematics of the genus Criniger, and a preliminary phylogeny of the bulbuls (Aves, Passeriformes, Pycnonotidae). Zoosystema23(4): 857–863. PDF fulltext