Weebill

{{Short description|Species of bird}} {{Speciesbox | name = Weebill | image = Weebill Smicrornis brevirostris) 12 September 2015 Cropped.jpg | image_caption = Nominate subspecies, Victoria | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2016 |title=''Smicrornis brevirostris'' |volume=2016 |article-number=e.T22704662A93979895 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22704662A93979895.en |access-date=12 November 2021}}</ref> | genus = Smicrornis | parent_authority = [[John Gould|Gould]], 1843 | species = brevirostris | authority = ([[John Gould (ornithologist)|Gould]], 1838) | range_map = Weebill_distribution.png | range_map_caption = Approximate range in Australia {{Leftlegend|#FF0000|Year-round range|outline=gray}} }} [[File:Weebill (Smicrornis brevirostris).jpg|thumb|right|Subspecies ''flavescens'', Northern Territory]] The '''weebill''' ('''''Smicrornis brevirostris''''') is a species of bird in the family [[Acanthizidae]]. It is an [[Insectivore|insectivorous]] [[passerine]] that is found throughout mainland [[Australia]]. At {{convert|8|to|9|cm|in|abbr=on}} long, it is Australia's smallest bird. It was originally described by [[John Gould]] in 1838, and four subspecies are recognised. The weebill's plumage is nondescript, with olive-grey upperparts and paler, more yellowish underparts. It grades from more brownish plumage in the southern regions of Australia to more yellow in tropical areas.

== Taxonomy == The weebill was described by John Gould in 1838 as ''Psilopus brevirostris''. The species epithet is derived from the [[Latin]] words ''brevis'' 'short' and ''rostrum'' 'beak'.<ref name=GrayFraser>{{cite book|last1=Gray|first1=Jeannie|last2=Fraser|first2=Ian|title=Australian Bird Names: A Complete Guide|url=https://books.google.com/books?id=W1TCqHVWQp0C&pg=PT184|year=2013|publisher=CSIRO Publishing|location=Collingwood, Vic. | isbn=978-0-643-10471-6|page=184}}</ref>

In 1843, Gould erected the genus ''Smicrornis'' for his new species ''Smicrornis flavescens'', collected from Port Essington, noting it as distinct from ''[[Gerygone]]'' (which had replaced ''Psilopus as a ''name'').<ref name=Gould>{{cite journal |last1=Gould |first1=John |title=Proceedings of meeting of Zoological Society of London, Oct. 11, 1842 |journal=Proceedings of the Zoological Society of London |date=1842 |volume=10 |pages=131–140 [133–134] |url=https://biodiversitylibrary.org/page/30679895}}</ref>'' The generic name ''Smicrornis'' derives from the Greek ''smicros'' 'small' and ''ornis'' 'bird'.<ref name=Helm>{{cite web|url=https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling|title=Helm Dictionary of Scientific Bird-names|last=Jobling|first=James A.|access-date = 2020-04-17}}</ref> It is the [[Monotypic taxon|only member]] of genus ''Smicrornis''; [[gene flow]] is strong and local variation follows [[Bergmann's rule|Bergmann's]] and [[Gloger's rule|Gloger's]] rules.<ref name="keast1958">{{cite journal |last1=Keast |first1=Allan |title=Geographic variation in the Weebill, Smicrornis brevirostris (Gould) (Passeres: Muscicapidae, malurinae) a sedentary species with a continuous range |journal=Australian Journal of Zoology |date=1958 |volume=6 |issue=2 |pages=152–161 |doi=10.1071/ZO9580152}}</ref><ref name=ALA>{{Cite web |url=https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:e2e2e858-5403-4981-8baf-b5202275fa7a |title=Smicrornis brevirostris: Weebill |work=Atlas of Living Australia |language=en-AU |access-date=2019-06-10}}</ref>

Gould initially called it the short-billed smicrornis, but it did not gain acceptance. Other names include tree-tit, short billed tree-tit, scrub-tit, or short-billed scrub-tit. Weebill was adopted as the name in the 1926 RAOU checklist.<ref name=GrayFraser/>

=== Subspecies === Four [[subspecies]] are currently recognised in addition to the nominate subspecies:<ref name=HBW/>

* S. ''b''. ''flavescens'' (Gould, 1843) – ranging across Northern Australia from the [[Kimberley (Western Australia)|Kimberley]] to northern and [[western Queensland]] (including [[Cape York Peninsula]]) and southward to the northern [[Great Sandy Desert|Great Sandy]] and [[Tanami Desert]]s, Central Australian ranges, northern [[Simpson Desert]] and central Thomson drainage. * ''S. b. ochrogaster'' (Schodde & Mason, 1999) – western and central [[Western Australia]] (south from the [[Pilbara]]). * ''S. b. occidentalis'' (Bonaparte, 1850) – southwest Western Australia (south from lower [[Murchison Range]] and [[Kalgoorlie]] region), eastward around southern rim of [[Nullarbor Plain]] to [[South Australia]] (southward from central [[Flinders Ranges]], lower [[Lake Frome]] basin and [[Murray Mallee]]). * ''S. b. brevirostris'' (Gould, 1838) – Eastern Australia from central and eastern Queensland ([[Burdekin River]] drainage), southward to [[Victoria (Australia)|Victoria]] and southeast South Australia.

== Description == The weebill is [[Australia]]'s smallest bird at approximately {{convert|8|to|9|cm|in|abbr=on}} long and weighing an average of 6 grams (adult bird).<ref name=HANZAB>{{Cite book|title=Handbook of Australian, New Zealand and Antarctic Birds, Volume 6: Pardalotes to Shrike-thrushes.|author=Higgins, P. J.|author2=J. M. Peter|name-list-style=amp|publisher=Oxford University Press|year=2002|isbn=0-19-553244-9|location=Melbourne}}</ref> Wingspan is approximately {{convert|15|cm|in|abbr=on}}.<ref name=HANZAB/>

Weebills have inconspicuously coloured [[plumage]] ranging from yellowish-grey (front) to olive-brownish-grey (back). The two main feather pigments involved in this variation are yellow ([[phaeomelanin]]) and olive-brown ([[eumelanin]]).<ref name="keast1958" /> There is geographical variation in plumage across the four subspecies.<ref name=HANZAB/>

Adults have pale yellow eyes and a faint cream coloured [[supercilium]]. The throat feathers are grey, often with striation, and the flight feathers on the wings are pale brown.<ref name=HANZAB/> The tail feathers are brown with a black bar and white spot on the tip of all the [[rectrices]], except the central pairs, which are completely dark.<ref name=ALA/> Both sexes are [[Monomorphism (biology)|monomorphic]] in plumage colouration.<ref name=HANZAB/>

The [[Beak|bill]] is short and pale grey.<ref name=HBW/> The stubby bill of the weebill assists in distinguishing it from [[Acanthiza|thornbills]].<ref name=Simpson>{{Cite book|title=Field guide to the birds of Australia|edition=5th|author=Simpson|author2=Day|name-list-style=amp|publisher=Penguin Books Australia Ltd.|year=1996|isbn=0-670-86305-X|location=Ringwood, VIC, Australia|pages=182}}</ref> The legs and feet of the weebill are grey, and like all passerines, their [[Bird feet and legs|toe arrangement]] is [[anisodactyl]] for perching.<ref name=HANZAB/>

Juveniles have a similar plumage to adults, but can be identified by a brighter, yellow bill and greyer eye.<ref name=Backyard/>

Four subspecies of weebill are currently recognised and exhibit slight variation in feather pigmentation, dependent on distribution.<ref name=HANZAB/> In the south and east of Australia, subspecies ''occidentalis'' and ''brevirostris'' are light brown; in the southwest, the subspecies ''occidentalis'' exhibits greyer plumage; while subspecies ''flavescens'' in northern and inland Australia is paler and more yellow.<ref name=mdahlem>{{Cite web |url=https://mdahlem.net/birds/17/weebill.php |title=Weebill (Smicrornis brevirostris) |website=mdahlem.net |access-date=2019-06-09}}</ref> Additionally, the Northern Australian weebills are smaller than those in the south.

The voice of the weebill is a loud, clear, musical ''pee-pee p'wee'', ''wee bit'' or ''wee willy weetee'', often heard from a considerable distance.<ref name=HANZAB/>

== Distribution and habitat == The weebill is found in [[woodland]]s and forests across most of mainland [[Australia]], excluding Tasmania.<ref name=FeathersPhotos>{{Cite web |url=http://www.feathersandphotos.com.au/forum/showwiki.php?title=Australian+Bird+Guide:Weebill+Smicrornis+brevirostris |title=Weebill (Smicrornis brevirostris) |website=Feathers and Photos |access-date=2019-06-09 |url-access=registration}}</ref> All four subspecies of weebills are sedentary in their range,<ref name=HANZAB/> and numbers are regular throughout the year.

They are most commonly found in the canopies of dry, open [[eucalyptus]] forests, woodlands and [[Mallee Woodlands and Shrublands|mallee]],<ref name=FeathersPhotos/> occasionally coming down to the [[Stratification (vegetation)|midstory]] to feed primarily on small insects and their larvae. They display a preference for foraging in the canopy foliage of healthy eucalyptus trees, where they are more likely to retrieve insects.<ref name=Fleming>{{Cite journal|last1=Fleming|first1=P. A.|last2=Hardy|first2=G. E. StJ|last3=Craig|first3=M. D.|last4=Valentine|first4=L. E.|last5=Moore|first5=T. L.|date=2013|title=Do woodland birds prefer to forage in healthy Eucalyptus wandoo trees?|journal=Australian Journal of Zoology|volume=61|issue=3|pages=187–195|doi=10.1071/ZO13045|s2cid=84595439|issn=0004-959X|url=https://research-repository.uwa.edu.au/en/publications/do-woodland-birds-prefer-to-forage-in-healthy-eucalyptus-wandoo-trees(78751a98-2a0d-4943-9adb-b03b92a16abf).html}}</ref> The weebill is widespread in all climates,<ref name=SchoddeMason>{{Cite book|title=The directory of Australian birds: passerines|author=Schodde, R.|author2=Mason, I. J.|name-list-style=amp|publisher=CSIRO Publishing|year=1999|isbn=978-0-643-06456-0|location=Collingwood, VIC, Australia}}</ref> although localised to watercourses in arid zones. They are somewhat gregarious with other small insectivorous passerines, such as [[Acanthiza|thornbills]], [[silvereye]]s, and [[pardalote]]s.

== Ecology == === Diet === The diet consists mostly of [[insect]]s, [[larva]]e, occasionally seeds and beetles .<ref name=HANZAB/> [[Arthropod]] prey items include spiders ([[Spider|Araneae]]), beetles ([[Beetle|Coleoptera]], including [[Curculionidae|Curculionids]]), and flies ([[Fly|Diptera]]).<ref name=HBW>{{Cite book|title=Handbook of the Birds of the World Alive; Volume 12: Picathartes to Tits and Chickadees|author=del Hoyo, J.|author2=Elliott, A.|author3=Sargatal, J.|author4=Christie, D.A.|author5=de Juana, E.|name-list-style=amp|publisher=Lynx Edicions|year=2007|isbn=978-84-96553-42-2|location=Barcelona}}</ref> Weebills forage busily in pairs, or small parties of up to 8, feeding mainly in trees, often hovering, they are active and noisy and cling to twigs while gleaning insects from the outer foliage of the canopy and midstory.

Weebills assist in maintaining the health of trees, as they [[Gleaning (birds)|glean]] scale insects and eat a range of other insects, including [[Psyllidae|psyllids]] and their protective covers [[Lerp (biology)|(lerps)]].<ref name=Serventy/>

=== Reproduction ===

The dome-shaped [[Bird nest|pendant nests]] of weebills are made from fine, pliable materials, such as grasses and plant fibres suspended from a branch and concealed in dense foliage of the tree canopy.<ref name=Serventy>{{Cite book|title=The Wrens and Warblers of Australia: The National Photographic Index of Australian Wildlife|last=Serventy|first=Vincent|publisher=Angus & Robertson|year=1982|isbn=0-207-14480-X|location=Australia}}</ref> Weebills are known to utilize cobwebs, insect cocoons and animal hair to bind, strengthen, and further conceal the nest.

The breeding season of weebills depends on latitude and climatic conditions.<ref name=mdahlem/> They can breed at almost any time of the year, but most commonly from July to May. Courtship displays have been observed in weebills, where males ruffle their cheek and head feathers with outstretched wings to the female. It is thought that male and female weebills display to each other at the nest-site with tail-fanning, slight bowing and wing quivering.<ref name=HANZAB/>

The female usually lays two to four brown-speckled cream-coloured [[Bird egg|eggs]],<ref name=HANZAB/> which are tapered-oval in shape. Only the female [[Egg incubation|incubates]] the eggs, which hatch after 10–12 days, and then both parents care for the chicks.<ref name=Backyard>{{Cite web |url=http://www.birdsinbackyards.net/species/Smicrornis-brevirostris |title=Weebill |website=Birds in Backyards |access-date=2019-06-10}}</ref>

Weebill eggs in the nest are occasionally vulnerable to small [[brood parasite]]s, such as the [[Horsfield's bronze-cuckoo]], where the female cuckoo removes the weebill eggs and lays one or two eggs in the host nest for the weebill to raise.<ref>{{Cite web |url=http://www.birdlife.org.au/bird-profile/horsfields-bronze-cuckoo |website=BirdLife Australia |title=Horsfield's Bronze-Cuckoo |language=en|access-date=2019-06-10}}</ref>

== Threats and conservation == Widespread and common in its habitat throughout its [[range (biology)|range]] on mainland Australia, the weebill is evaluated as [[Least Concern]] on the [[IUCN Red List]] of Threatened Species.<ref name="iucn status 12 November 2021" /> However, like many woodland birds throughout Australia, local declines have been noted, these being consequent upon [[Habitat destruction|habitat loss]] and fragmentation caused by deforestation of ''[[Eucalyptus]]'' woodlands<ref>{{cite magazine |url=http://www.birdlife.org.au/documents/WL-woodland_birdsWS.pdf |title=Woodland birds: the next generation |date=Winter 2011 |magazine=Wingspan |pages=22–25 |first1=Dean |last1=Ingwersen |first2=Chris |last2=Tzaros |access-date=2019-06-09 |archive-date=2021-06-30 |archive-url=https://web.archive.org/web/20210630180226/https://www.birdlife.org.au/documents/WL-woodland_birdsWS.pdf }}</ref> and other [[Human impact on the environment|anthropogenic changes]] to the characteristics of the land.

Human-caused disturbances include introduced flora and fauna species, and altered fire regimes that can result in changes to ecosystem-level processes, modify habitat structure and consequently affect fauna assemblages.<ref name=Valentine>{{Cite thesis|title=The impacts of human-mediated disturbances on birds and reptiles in tropical savannas|url=https://trove.nla.gov.au/version/47062090|date=2009|first=Leonie|last=Valentine}}</ref>

== References == {{Reflist}} {{refbegin}} * {{cite book |editor1-last=Hoyo |editor1-first=J. del |editor2=Elliot, A. |editor3=Christie, D. |year=2006 |title=Handbook of the Birds of the World |volume=12: Picathartes to Tits and Chickadees |publisher=Lynx Edicions |isbn=978-84-96553-42-2 |name-list-style=amp}} {{refend}}

== External links == *{{Commons category-inline|Smicrornis brevirostris|''Smicrornis brevirostris''}} *{{Wikispecies-inline|Smicrornis brevirostris|''Smicrornis brevirostris''}}

[[Category:Acanthizidae]] [[Category:Endemic birds of Australia]] [[Category:Birds described in 1838]] [[Category:Taxa named by John Gould]]