The bare-faced bulbul (''Nok hualon'') is a member of the

bulbul The bulbuls are members of a family, Pycnonotidae, of medium-sized passerine songbirds, which also includes greenbuls, brownbuls, leafloves, and bristlebills. The family is distributed across most of Africa and into the Middle East, tropical As ...

family of

passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s. It was newly described from central Laos in 2009. It is one of the very few Asian

songbird A songbird is a bird belonging to the suborder Passeri of the perching birds (Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes contains 500 ...

s with a bald (featherless) face and is the first new species of bulbul to be described from Asia in almost a century.

Taxonomy and systematics

The species epithet ''hualon'' is from the Lao word for "bald-headed". A 2018 molecular phylogenetic study of the bulbuls suggested that the species does not fit in the clade containing the core ''Pycnonotus'' and stood apart suggesting its placement in a new genus ''Nok'' from Lao language for "bird" as ''Nok hualon''.

Description

The mainly olive-green bare-faced bulbul is distinctive in having a bare pink face with blueish skin around the eyes. The two specimens so far collected were around 20 cm in length and weighed 32-40 g. The breast and belly are fawn-grey, the uppersides olive and the throat is off-white. According to researchers, its call is a "dry bubbly tweet".

Habitat

The bare-faced bulbul is known only from the limestone

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

region near Pha Lom in central

Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...

. The area is characterised by steep terrain with bare limestone and low (less than 4 m in height)

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

trees and shrubs. It seems likely that the species is restricted entirely to this habitat, though it may occur at other sites in Laos with similar habitats. Observations of similar birds were made in 1995 at another site. Limestone karst is the habitat of several newly discovered

endemic species Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

, including the unusual

Laotian rock rat The Laotian rock rat or ''kha-nyou'' (''Laonastes aenigmamus'', Lao: ຂະຍຸ), sometimes called the "rat-squirrel", is a species of rodent found in the Khammouan region of Laos. The species was first described in a 2005 article by Paulina ...

Behaviour

The bare-faced bulbul is mainly arboreal but sometimes perches on rocks on the steep hillsides. It is a conspicuous species, foraging during the day in pairs or as singles. Single birds tend to call regularly, and will link up with another before flying to a new area to forage. They have not been observed to join

mixed-species feeding flock A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These ar ...

s. The breeding behaviour of this species has not yet been observed.

Status and conservation

The bare-faced bulbul was assessed for the first time in 2010 by

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...

as of

Least Concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

, on the basis that the species has a large range, and there is insufficient evidence on population trend and size.Birdlife Species Factsheet
/ref> In the paper describing the species it was suggested that it be listed as

data deficient A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...

until further surveys of likely habitat were undertaken. The limestone karst in which it lives is threatened by quarrying and

habitat degradation Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

caused by

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...

References

External links

Notes on the bird prior to its formal description by Stijn De Win
{{Taxonbar, from=Q781347 bare-faced bulbul Birds of Laos bare-faced bulbul