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Isabela oriole
Conservation status
	; Critically Endangered (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Oriolidae
Genus:	Oriolus
Species:	O. isabellae
Binomial name
	Oriolus isabellae; Ogilvie-Grant, 1894
	Known locations of sightings or collections

The Isabela oriole (Oriolus isabellae) is a species of the oriole family endemic to Luzon in the Philippines. It is an oriole identified by its yellowish green plumage and a very large gray bill. This species was presumed to be extinct for many years until its rediscovery in December 1993 near Diffun, Quirino,^[2] and in Mansarong in September 1994.^[3] Additional sightings were made in San Mariano, Isabela. and Baggao, Cagayan Valley^[4] It It is found in moist lowland forest up to 440 masl. It is critically endangered with estimates of just 50 to 250 mature individuals remaining. It is threatened by habitat loss and hunting.

Description and taxonomy

It is described on EBird as "A medium-sized bird of lowland forest, including secondary habitats and bamboo in northern Luzon. Yellow underparts blend into olive upperparts. Bill fairly long and silver. Forages for fruit and insects, sometimes in mixed-species flocks. Similar to White-lored Oriole, but slightly larger, with a silver rather than red bill and no white spot in front of the eye. Song consists of a medium-pitched, upslurred whistle, “hoowit!”^[5] This species is monotypic.

The Isabela oriole is commonly confused with the much more common white-lored orioles and black-naped orioles. It is differentiated by its extremely large bill grey bill, uniform olive-yellow plumage and lack of white on its lores.

The Isabela oriole is most closely related to the white-lored oriole. Both species are closely related to the paraphyletic Philippine oriole.^[6] The Isabela oriole is sometimes considered to form a superspecies with the dark-throated oriole and the Philippine oriole.^[7] Alternate names for the Isabela oriole include the green-lored oriole and olive-lored oriole.

Ecology and behavior

Feeds mostly on fruit but also insects such as larvae and caterpillars. Typically seen alone, in pairs or small groups in the middle storey to the canopy. It is seen in mixed flocks with other birds such as bar-bellied cuckooshrikes, black-and-white trillers, blackish cuckooshrikes and other forest birds.

Breeding believed to occur during April to June. In 2022, the first record and photographs of a juvenile were released.^[8]

Distribution and habitat

The Isabela oriole is now confined to the lowland forests in the Northern Sierra Madre mountain range in Luzon.^[9] It is frequently seen in the canopy and middle storeys of forests and also forest edge or patches up to 440 masl.

It has not been recorded in Bataan province since 1947 despite an intensive search done in 2014.^[1]

Conservation status

The Isabela oriole has a known population of about 50-250 mature individuals and is assessed as Critically Endangered based on its extremely small and fragmented population.^[1] Organisations such as Buhay-Ilang, ORIS Project and the Mabuwaya Foundation are working to conserve them with educational programs and festivals celebrating this bird. The oriole is now a Flagship species for the North Sierra Madre National Park.

Since 2015, a research and conservation project for the Isabela Oriole has been implemented in Baggao by the Mabuwaya Foundation. Information, education and communication, community consultations are held in Baggao with the local government, the Department of Environment and Natural Resources and local residents. Plans are underway to declare the oriole site in Baggao a Critical Habitat and to encourage ecotourism.^[10]

Under the Philippine law RA9147, it is completely illegal to hunt these birds or to capture and keep them as pets.^[11] As it is crically endangered species on the Philippine Red List, any violations have harsher punishments including "imprisonment of a minimum of six (6) years and one (1) day to twelve (12) years and/or a fine of One hundred thousand pesos (100,000.00) to One million pesos (1,000,000.00), if inflicted or undertaken against species listed as critical"

References

^ ^a ^b ^c BirdLife International (2018). "Oriolus isabellae". IUCN Red List of Threatened Species. 2018: e.T22706378A134213171. doi:10.2305/IUCN.UK.2018-2.RLTS.T22706378A134213171.en. Retrieved 12 November 2021.
^ Gamauf, Anita; Tebbich, Sabine (February 1996). "Re-discovery of the Isabela Oriole, Oriolus isabellae" (PDF). Forktail. 11: 170–171. ISSN 0950-1746.
^ van der Linde, K. (1996). "A further record of the Isabela oriole (Oriolus isabellae) from Baggao, Cagayan Province, northern Philippines." Forktail 11: 171.
^ van Weerd, M. and Hutchinson, R. (2004) "Observations of Isabela Oriole Oriolus isabellae in the Sierra Madre, Luzon, Philippines, with descriptions of the call." Forktail 20: 133-136. [1] Archived 2012-04-14 at the Wayback Machine
^ "Isabela Oriole - eBird". ebird.org. Retrieved 2024-09-10.
^ Knud A. Jønsson, Rauri C. K. Bowie, Robert G. Moyle, Martin Irestedt, Les Christidis, Janette A. Norman, Jon Fjeldså (2010) Phylogeny and biogeography of Oriolidae (Aves: Passeriformes) Ecography 33(2): 232–241 doi:10.1111/j.1600-0587.2010.06167.x
^ "Dark-throated Oriole (Oriolus xanthonotus)". www.hbw.com. Retrieved 2017-02-24.
^ "Juvenile Isabela Oriole". Facebook. Mabuwaya Foundation.
^ "Oriolus isabellae - Avibase". avibase.bsc-eoc.org. Retrieved 2017-02-25.
^ International), BirdLife International (BirdLife (2018-08-20). "IUCN Red List of Threatened Species: Oriolus isabellae". IUCN Red List of Threatened Species. Retrieved 2021-09-04.
^ "Republic Act 9147". www.officialgazette.gov.ph. Retrieved 2021-09-08.