Blue-wattled Bulbul Microtarsus nieuwenhuisii Scientific name definitions

18 cm. Nominate subspecies has head dark gray-brown to blackish, with vaguely hooded effect; cheeks and forehead washed greenish-olive; mantle rich olive-green, loose and plush feathering of lower back banded darker at base (showing as dark bars when ruffled), rump paler green-gray; wings and tail dark grayish-brown, broadly fringed olive-green on remiges and rectrices, latter with dark brown subter­minal band and small whitish tips; chin and throat dark gray-brown to blackish, merging with dark olive of breast, this in turn merging with pale greenish-yellow of belly and vent; iris warm brown, conspicuous pale fleshy blue eyelids; bill black; legs plumbeous. Sexes alike. Juvenile undescribed. Subspecies inexspectatus is slightly brighter and paler, marginally greener and less grayish on upperparts, paler yellow on underparts, with head less blackish, more gray, dark throat contrasting less sharply with breast, iris red, edges of eyering pale blue, bill and legs black.

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Sometimes placed in Microtarsus. Owing to its extraordinary rarity (known from two specimens, each a taxonomic type, and some observations in Brunei), present species has been suggested to be a hybrid, since an enlarged and differently colored eyering has previously been recorded in pycnonotid hybrids (1 Williams, R.S.R. (2002). The rediscovery and doubtful validity of the Blue-wattled Bulbul Pycnonotus nieuwenhuisii. Forktail 18: 107–109. Close ); however, while one parent would probably be a Black-headed Bulbul (Microtarsus melanocephalos), a plausible second parent is much harder to match against the characters produced (2 Collar, N.J. (2014). Blue-wattled Bulbul Pycnonotus nieuwenhuisii and Black-browed Babbler Malacocincla perspicillata: two Sundaic passerines in search of a life. BirdingASIA 21: 37–44. Close ). The possibility that the form is a rare morph is discounted because it does not appropriately fit any species (1 Williams, R.S.R. (2002). The rediscovery and doubtful validity of the Blue-wattled Bulbul Pycnonotus nieuwenhuisii. Forktail 18: 107–109. Close ). Thus, it seems better maintained as a species at least until genetic analysis illuminates its status (2 Collar, N.J. (2014). Blue-wattled Bulbul Pycnonotus nieuwenhuisii and Black-browed Babbler Malacocincla perspicillata: two Sundaic passerines in search of a life. BirdingASIA 21: 37–44. Close ). Two subspecies recognized.

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Insufficient data. Sumatran specimen was taken in low shrubbery on a river island, at 700 m; the Bornean one in tall primary evergreen forest at 610 m, and reported at all levels in same habitat, down to 60 m in north (Brunei). Given the paucity of records, very few conclusions can be drawn regarding the ecology of this species.

Insufficient data. In Brunei, seen while feeding with other bulbuls (including the Black-and-white Bulbul (Microtarsus melanoleucos) and Black-headed Bulbul (Microtarsus melanocephalos)) on fruiting trees, including Macaranga aetheadenia. In Sumatra, the single specimen perched near (but not directly associating with) large numbers of Black-headed Bulbul gathered at fruiting shrubs.

Unknown; “harsh but quiet notes” thought to be made by this bulbul in Brunei.

Not globally threatened. Currently considered Data Deficient. Restricted-range species: present in the Bornean Mountains EBA and Sumatra and Peninsular Malaysia EBA. Extremely rare: only two specimens known, and very few observations. After the Sumatran specimen (inexspectatus) was taken, the collector spent several days in combing the area for a second individual, but failed to encounter one; in Borneo, the site of discovery of nominate subspecies was revisited after several years, but no further individuals were found. Only subsequent information stems from five observations of single birds (perhaps the same individual) at Kuala Belalong, in Batu Apoi Forest Reserve (Brunei) in 1992 (3 Williams, R.S.R. (2002). The rediscovery and doubtful validity of the Blue-wattled Bulbul Pycnonotus nieuwenhuisii. Forktail. 18: 107-109. Close ). Although this taxon was listed as globally threatened in the 20th century, it was removed from consideration (officially Not Evaluated) for several years because of the belief that it was probably a hybrid (4 Collar, N.J. (2014). Blue-wattled Bulbul Pycnonotus nieuwenhuisii and Black-browed Babbler Malacocincla perspicillata: two Sundaic passerines in search of a life. BirdingASIA. 21: 37-44. Close ) BirdLife International (2015) Species factsheet: Pycnonotus nieuwenhuisii. Downloaded from http://www.birdlife.org on 06/11/2015. . Primary objective is to determine whether it is a true species; to achieve this aim, a molecular analysis of existing specimens is under way (4 Collar, N.J. (2014). Blue-wattled Bulbul Pycnonotus nieuwenhuisii and Black-browed Babbler Malacocincla perspicillata: two Sundaic passerines in search of a life. BirdingASIA. 21: 37-44. Close ). Renewed searches of likely habitat should be conducted, focusing on regions near the specimen localities, and Batu Apoi Forest Reserve. The 1992 sightings come from the "conservation extension" (IUCN Cat. Ia; 26 km²) of Batu Apoi Forest Reserve (3 Williams, R.S.R. (2002). The rediscovery and doubtful validity of the Blue-wattled Bulbul Pycnonotus nieuwenhuisii. Forktail. 18: 107-109. Close , 4 Collar, N.J. (2014). Blue-wattled Bulbul Pycnonotus nieuwenhuisii and Black-browed Babbler Malacocincla perspicillata: two Sundaic passerines in search of a life. BirdingASIA. 21: 37-44. Close ).