In line with science development, bird diversity in Indonesia is ever-changing through time, counting to 1818 species by early 2022. The number was also influenced by the merging and segregation of species. Meanwhile, the highest risk of bird extinction in the world currently occurs in Indonesia.
Achmad Ridha Junaid, Biodiversity Officer of Burung Indonesia, informed that according to data collected in 2022, 177 bird species are in the endangered category. This number consists of 96 Vulnerable (VU) species, 30 Critically Endangered (CR) species, 51 Endangered (EN) species, and 30 Critically Endangered (CR) species. The Critical Citron-crested Cockatoo (Cacatua citrinocristata), a subspecies of the Yellow-crested Cockatoo, is included. This information has brought Indonesia to the top list country with the most endangered bird species, reaching a number of 12%.
"BirdLife International and the International Union for Conservation of Nature (IUCN) conduct an annual reassess on threat status of a number of species in response to changes in threat levels, population changes, taxonomic revisions, and also recent data related to the species being studied," Ridha said in Bogor, Friday (29/4).
The three species Maleo (Macrocephalon maleo), Crested Partridge (Rollulus rouloul) and Green Imperial-pigeon (Ducula aenea) are among the birds with the increase of threat status. Maleo birds incubate their eggs by burying them in the sand. However, about two-thirds of known Maleo nesting sites are no longer visited by adult birds, and the number of visitors on active nesting sites in the last three generations has been dwindling.
Ridha asserted, "Decreasing lowland forest in its distribution area has driven the extinction threat of Maleo to increase to its current Critical status.”
The estimated population of the Crested Partridge has dropped 30% in the last three generations, following the habitat loss and illegal hunting. Currently, the Crested Partridge is among globally endangered species, categorized on Vulnerable status. The population number of Green Imperial-pigeon due to forest cover clearance is on worrying decline, causing the species to be included in the Near Threatened (NT) category. Meanwhile, the Javan Plover (Charadrius javanicus), which was suspected to have a limited distribution on the coast of Java and Kangean Islands, has been downlisted from its previous threat status. Additional evidence and reports from the field confirm that this species also inhabits the coasts of southern Sumatra (Lampung), Sulawesi, Meno, Semau, and Flores. “Thus, the species is no longer approaching the Vulnerable thresholds and has now been classified to Least Concern (LC) category,” Ridha remarked.
Species increase
Ridha explained that in the period of early 2021 to early 2022, there were eight additional species. Three among them are newly-described species, two are Indonesia’s new encounter records, and the last three are additional species caused by revisions on classification or bird taxonomy.
The newly-described species are the Meratus Jungle Flycatcher (Cyornis kadayangensis), Meratus White-eye (Zosterops meratusensis), and Satin Berrypecker (Melanocharis citreola). The Meratus Jungle Flycatcher and Meratus White-eye are on very limited distribution in Kalimantan Island. Both birds are estimated to only exist in the Meratus Mountains above an altitude of 1,000 m asl, which is currently surrounded by secondary forests or plantation landscapes at lower elevations.
“Despite their locally abundant numbers, their population in nature is under the threat of habitat loss and hunting. Therefore, the researchers who described the two species proposed that they be categorized as endangered species in the Vulnerable category,” Ridha said.
The Satin Berrypecker, according to Ridha’s explanation, is a new species with a very limited distribution in Papua Island. Findings from the expedition proved that berrypecker species found in Kumawa Mountains and Fakfak Mountains had morphological and genetic differences with other species which scattered on other parts of Papua.
"The bird is estimated to only exist in the two mountain forests and is designated as a separate species," he explained.
Meanwhile, the two additional species are the Black-tailed Whistler (Pachycephala melanura) and the Dimorphic Jewel-babbler (Ptilorrhoa geislerorum). Their main distribution is outside the Indonesian boundary, but recent observation proved that both species are also spread across the country.
The Black-tailed Whistler, whose main distribution is in Australia and Papua New Guinea, was confirmed to be in Indonesia through observation records collected on the citizen science platform (e-Bird). The observation location is on Komolom Island, West Papua. Previously known to be on limited distribution in Papua New Guinea, the Dimorphic Jewel-babbler was spotted 900 kilometers further west in Yapen Island, Papua.
Ridha added, “The population of the Dimorphic Jewel-babbler in Yapen Island is suspected to be isolated from other populations. Therefore, further research is needed to ascertain the possibility of population divergence as a separate new subspecies.”
The bird taxonomy revision, in particular the taxonomy segregation, also contributed to the increase in the number of bird species in Indonesia this year. The Oriental Cuckoo (Cuculus optatus), Tanahjampea Blue-flycatcher (Cyornis djampeanus), and Citron-crested Cockatoo are the three species that have been added to the list of bird species in Indonesia this year after recognized as full species.
The Oriental Cuckoo and Tanahjampea Blue-flycatcher were treated as species on their own after informations which prove their differences in morphological characteristics and vocalizations with their cousins the Himalayan Cuckoo (Cuculus saturatus) and the Mangrove Blue-flycatcher (Cyornis rugastra), respectively. For the Citron Crested Cockatoo, differences in morphological characteristics are the main basis for separating this species from the Yellow Crested Cockatoo (Cacatua sulphurea). “Larger bill, longer wings and tail, dominantly pale-orange ear patches, and long orange crest. Also, the juvenile has a darker colored bill compared to other yellow-crested cockatoos, thus strengthening the reason for the separation of the Citron Crested Cockatoo and recognition as separate species,” Ridha concluded.
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For further information, please contact:
Achmad Ridha Junaid
Biodiversity Conservation Officer Burung Indonesia Email: a.ridha@burung.org HP: 0823-1123-0749
Kukuh Akhfadaturrahman Tohari
Communications Officer Burung IndonesiaEmail: t.kukuh@burung.org
HP: 0811-1915-0925
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