The Gilbert's whistler (''Pachycephala inornata'') is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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 ...

endemic 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 ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, scattered in semi-arid zones of southern Australia.

Taxonomy

The family

Pachycephalidae The Pachycephalidae are a family of bird species that includes the whistlers, shrikethrushes, and three of the pitohuis, and is part of the ancient Australo-Papuan radiation of songbirds. The family includes 64 species that are separated into f ...

originated within the Australo-Papuan region. Together with the

red-lored whistler The red-lored whistler (''Pachycephala rufogularis'') is one of nine species of whistler occurring in AustraliaMenkhorst, Peter; Rogers, Danny & Clarke, Rohan (2017). '' The Australian Bird Guide''. Clayton South: CSIRO Publishing. p. 476. . and ...

and the

olive whistler The olive whistler (''Pachycephala olivacea'') or olivaceous whistler, is a species of bird in the family Pachycephalidae, the whistlers, that is native to southeastern Australia. Taxonomy and systematics Subspecies Five subspecies are recog ...

, the Gilbert's whistler is basal to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Pachycephala ''Pachycephala'' is a genus of birds native to Oceania and Southeast Asia. They are commonly known as typical whistlers. Older guidebooks may refer to them as thickheads, a literal translation of the generic name, which is derived from the Ancien ...

– the typical whistlers. This old

lineage Lineage may refer to: Science * Lineage (anthropology), a group that can demonstrate its common descent from an apical ancestor or a direct line of descent from an ancestor * Lineage (evolution), a temporal sequence of individuals, populati ...

represents a relictual form that was once more widespread. John Gould, who first described this

in 1841, named it after Mr Gilbert who discovered the

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

and collected specimens that he handed over to Gould. As for its

scientific name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

– ''Pachycephala inornata'' – in

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''pachys'' and ''kephale'' respectively mean ‘thick’ and ‘head’; several of the members of the

are indeed called ‘thickheads’, and other

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s for the Gilbert's whistler include black-lored Gilbert thickhead, red-throated thickhead, Gilbert's thickhead, or simply thickhead. With ‘inornatus’ meaning ‘plain’ in

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

, the second part of its

binominal name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

is attributed to the Gilbert's whistler's

plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...

, which is often described in the literature as being plain. There are several entries in the GenBank DNA sequence database for ''Pachycephala inornata.''

Description

The adult male, which weighs 29.8-32.5 g, possesses a rufous coloured chin and throat from its third year of life, as does its most likely closest relative, the

. Both males can easily be differentiated by the colour of their lores: black for the Gilbert's and red for the

. The female Gilbert's whistler (23.5-32.2 g) has a pale grey throat and a white ring around the eye; her underparts can be lightly streaked. Both sexes are uniformly brownish-grey, and have a red iris and a black stubby

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Plac ...

(17–18 mm). Juveniles (30.9 g) are darker than adults, with tinges of brown, and have dark streaks on the breast and belly. Immatures are very similar to adult females except for their brown

and dark brown iris. Care should be taken not to mistake the female and immature Gilbert's whistler for the female

golden Golden means made of, or relating to gold. Golden may also refer to: Places United Kingdom *Golden, in the parish of Probus, Cornwall *Golden Cap, Dorset *Golden Square, Soho, London *Golden Valley, a valley on the River Frome in Gloucestershir ...

western whistler The western whistler (''Pachycephala fuliginosa'') is a species of bird in the family Pachycephalidae found in southwest Australia. Prior to 2015, the western whistler was considered as a subspecies of the Australian golden whistler until recognize ...

s where they co-exist. At one stage, the Gilbert's whistler was divided into two

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

: ''Pachycephala inornata inornata'' in the east of the Flinders Ranges with greyish white underparts, and ''Pachycephala inornata gilberti'' in the west with cinnamon and buff underparts; this variation is now considered clinal. A study undertaken by Onley, Gardner and Symonds (2020) on possible larger

appendage An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...

s in whistlers caused by

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

( Allen's rule) from museum specimens collected between 1915 and 2013, found an increase in the body size of the Gilbert's whistler at higher

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

s, following

Bergmann's rule Bergmann's rule is an ecogeographical rule that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer ...

Ecology

Diet

Gilbert's whistlers feed mostly on the ground, as does about half of all declining species of birds in southern Australia. This species also forages in understorey layers. They feed primarily on

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s, although

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

and

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s can also form part of its diet.

Nesting and clutch

Gilbert's whistlers erect a deep cup nest in dense shrub, often on top of old babblers’ nests. Both sexes build the nest, incubate two or three, sometimes four eggs over a period of 15 days, and look after the chicks. Young are altricial and nidicolous.

Vocalisations

All whistlers are

songsters A "songster" is a wandering musician, usually but not always African-American, of the type which first appeared in the late 19th century in the southern United States. Songsters in American culture The songster tradition both pre-dated and co-exi ...

, and the Gilbert's whistler, in particular, is more often heard than seen. Its loud, melodious and clear call can be heard at distances up to 900 m, mostly during the breeding season when it establishes a breeding territory. Its

song A song is a musical composition intended to be performed by the human voice. This is often done at distinct and fixed pitches (melodies) using patterns of sound and silence. Songs contain various forms, such as those including the repetitio ...

is described as a series of swelling cheop, cheop, cheop repeated five to 20 times, with another ascending call er-WHIT, er-WHIT, er-WHIT similar to the rufous whistler, and also a more scratchy call eechowk, eechOWK, eeCHOWK.

Habitat, distribution and threats

The Gilbert's whistler inhabits semi-arid tall mallee with sparse shrubby understorey or prickly ''

Acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...

'' thickets and ''

Casuarina ''Casuarina'' is a genus of 17 tree species in the family Casuarinaceae, native to Australia, the Indian subcontinent, southeast Asia, islands of the western Pacific Ocean, and eastern Africa. It was once treated as the sole genus in the fami ...

'' woodlands, and is also found in thickets of ''

Melaleuca ''Melaleuca'' () is a genus of nearly 300 species of plants in the myrtle family, Myrtaceae, commonly known as paperbarks, honey-myrtles or tea-trees (although the last name is also applied to species of '' Leptospermum''). They range in size ...

'' and, occasionally, in taller eucalypt woodlands or forests. A study undertaken in 2017 on the effect of bushfires and prescribed burns on the distribution of 12

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensat ...

bird species predicted that

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

burnt between 30 and 60 years approximately would be favoured by Gilbert's whistlers while

burnt more frequently or not burnt for more than 60 years would not readily suit this species. The

distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations * Probability distribution, the probability of a particular value or value range of a vari ...

of Gilbert's whistlers is scattered in the semi-arid parts of southern

and

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

, north west Victoria and central west

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

. No large scale movements were recorded for the species which is thought to be

resident Resident may refer to: People and functions * Resident minister, a representative of a government in a foreign country * Resident (medicine), a stage of postgraduate medical training * Resident (pharmacy), a stage of postgraduate pharmaceutic ...

or sedentary with a high degree of

site fidelity Philopatry is the tendency of an organism to stay in or habitually return to a particular area. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, may be the most common. The term derives ...

. It is therefore not surprising that this species is sensitive to

disturbance Disturbance and its variants may refer to: Math and science * Disturbance (ecology), a temporary change in average environmental conditions that causes a pronounced change in an ecosystem * Disturbance (geology), linear zone of faults and folds ...

, as described by Murphy following a study on the conservation value of small woodland remnants in

, where he noted that the

of Gilbert's whistler in this region is largely restricted to the remaining original

vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic character ...

. Another project undertaken by a

bird banding 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 lightweight ...

group in the Charcoal Tank Nature Reserve in central west

sadly recorded the

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

of the Gilbert's whistler in this patch of remnant

during the ‘ Big Dry’ in 2000–01. This

local extinction Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

, a classic example of the ‘

Extinction Debt In ecology, extinction debt is the future extinction of species due to events in the past. The phrases dead clade walking and survival without recovery express the same idea. Extinction debt occurs because of time delays between impacts on a speci ...

’, was mainly attributed to:

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...

land clearing Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...

for agriculture during the last 100 years,

introduced predators An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its indigenous (ecology), native distributional range (biolog ...

, increased

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

from other native species, and

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

periods exacerbated by

. Additional details on these threats are outlined on the NSW Government species profile page.

Conservation

Of the four states in which the Gilbert's whistler occurs, this species is listed vulnerable only in

under the NSW Biodiversity Conservation Act 2016 based on population decrease in size and

. A

conservation Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws. Conservation may also refer to: Environment and natural resources * Nature conservation, the protection and manageme ...

strategy was developed in 2015 as part of the Saving our Species program with some of the priority management areas including: restoring

native vegetation In biogeography, a native species is indigenous to a given region or ecosystem if its presence in that region is the result of only local natural evolution (though often popularised as "with no human intervention") during history. The term is equi ...

, removing weeds, implementing actions to reduce the impact of

noisy miner The noisy miner (''Manorina melanocephala'') is a bird in the honeyeater family, Meliphagidae, and is endemic to eastern and southeastern Australia. This miner is a grey bird, with a black head, orange-yellow beak and feet, a distinctive yellow ...

s when deemed necessary, encouraging landholders to implement sensitive

grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...

practices, strip

burning Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...

with refuge areas remaining unburnt for 25 years or more, raising

public awareness In public relations and communication science, publics are groups of individual people, and the public (a.k.a. the general public) is the totality of such groupings. This is a different concept to the sociological concept of the ''Öffentlichkei ...

of the importance of large old trees, revegetating, and identifying methods to improve soil quality. The Gilbert's whistler is not listed at national level under the Environment Protection and Biodiversity Conservation Act 1999, and is listed as

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 ...

at international level under the IUCN Red List of Threatened Species 2016.

Image gallery

File:Naturalis Biodiversity Center - RMNH.AVES.130044 1 - Pachycephala inornata gilbertii Gould, 1844 - Pachycephalidae - bird skin specimen.jpeg, Bird skin specimen, Gilbert's whistler (''Pachycephala inornata)'' (Gould, 1844) File:Gilbert's Whistler (Pachycephala inornata) (8079675892).jpg, Male Gilbert's whistler (''Pachycephala inornata)'' File:Gilbert's Whistler (Pachycephala inornata) (31380214646).jpg, Female Gilbert's whistler (''Pachycephala inornata)''

References

{{Reflist Gilbert's whistler Birds of Western Australia Birds of South Australia Birds of New South Wales Birds of Victoria (Australia) Endemic birds of Australia Gilbert's whistler Taxonomy articles created by Polbot