{{Short description|Species of bird}} {{Speciesbox | image = Tapicuru de cara palida.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 14 November 2021">{{cite iucn |author=BirdLife International |date=2016 |title=''Cercibis oxycerca'' |volume=2016 |article-number=e.T22697432A93613688 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22697432A93613688.en |access-date=14 November 2021}}</ref> | taxon = Cercibis oxycerca | parent_authority = Wagler, 1832 | authority = (Spix, 1825) | synonyms = *''Ibis oxycercus'' <small>Spix, 1825</small> *''Geronticus oxycercus'' <small>(Spix, 1825)</small> | synonyms_ref = <ref name = Gray>{{cite book | author = G.R. Gray | year = 1849 | title = The genera of birds: comprising their generic characters, a notice of the habits of each genus, and an extensive list of species referred to their several genera | volume = 3 | page = 566 | url = https://www.biodiversitylibrary.org/bibliography/60796#/summary | publisher = Longman, Brown, Green, and Longmans}}</ref><ref name = HBW>{{cite web | author1 = Matheu, E. | author2 = del Hoyo, J. | author3 = Garcia, E.F.J. | author4 = Boesman, P. | name-list-style = amp | year = 2019 | title = Sharp-tailed Ibis (Cercibis oxycerca) | editor1 = del Hoyo, J. | editor2 = Elliott, A. | editor3 = Sargatal, J. | editor4 = Christie, D.A. | editor5 = de Juana, E. | work = Handbook of the Birds of the World Alive | publisher = Lynx Edicions, Barcelona. | url = https://www.hbw.com/species/sharp-tailed-ibis-cercibis-oxycerca | access-date = 6 January 2019}}</ref> | range_map = Sharptailedibisworlddistribution.png | range_map_caption = Current world extant distribution according to the IUCN (2012)}}
The '''sharp-tailed ibis''' ('''''Cercibis oxycerca''''') is a species of ibis native to open wet savannas in parts of northern South America.
==Taxonomy and systematics== The sharp-tailed ibis is monotypic, being the only representative of the genus ''Cercibis''.<ref name="Blake">Blake ER. 1977. ''Manual of Neotropical Birds'', vol I. University of Chicago Press, Chicago.</ref> Much remains unknown about this ibis's evolutionary history;<ref name="Hancock">Hancock JA, Kushlan JA, Kahl MP. 1992. ''Storks, Ibises and Spoonbills of the World''. Academic Press.</ref> however, phylogenetic analyses based on skull morphology and function suggest that it is closely related to the spoonbills.<ref>Ferreira CD. 2007. Filogenia dos Ciconiiformes (Aves) com enfase em Threskiornithidae. Open access thesis. Botucatu.</ref>
==Description== This large ibis measures 75–86 cm in length, with males being slightly larger than females.<ref name = "Hancock"/> In adult males, the flat wing measures 390–415mm lengthways, and the culmen measures 156–168mm from the base of the bill.<ref name = "Blake"/> In adult females, the wing is 376–413mm long and the culmen 144–197mm.<ref name ="Blake"/>
The species is distinguished by its notably long tail, the longest among all extant ibis species;<ref name="van Perlo">Van Perlo B. 2009. ''A Field Guide to the Birds of Brazil''. OUP USA, First Edition.</ref> measuring 250–301mm in males and 256–272mm in females.<ref name = "Blake"/> The tail projects beyond the tips of the folded wings when the ibis stands; and beyond the trailing legs in flight.<ref name="Hancock"/> The plumage is predominantly black with greenish glossing;<ref name = "Blake"/><ref name="Hancock"/> and with purplish tinges on the upper back, hindneck, wings and tail.<ref name="Blake"/><ref name="Hancock"/> The forehead and cheek region are occasionally greyish brown.<ref name="Blake"/> Juveniles appear similar to adults, but their plumage lacks a metallic sheen.<ref name="Hancock"/>
The bill, legs, toes, and bare facial skin are orangey-red; the throat is yellowish-orange, and a feathered grey strip extends below the eye from the lower mandible. An inconspicuous fuzzy crest extends down the back of its head and upper neck. The iris is greyish red, but is sometimes scarlet red, which may be associated with breeding.<ref name="Hancock"/> Nothing is however known of changes in soft part colourations as part of courtship.<ref name="Hancock"/> Overall, the sharp-tailed ibis is superficially similar to many sympatric ibises such as the glossy ibis<ref name="Hancock"/> and the bare-faced ibis;<ref name="Hilty">Hilty SL. 2002. ''Birds of Venezuela''. Princeton University Press. 2nd Edition.</ref> but clearly differs through its longer tail and larger body size.<ref name="Hancock"/>
This ibis is particularly vocal. The call is a loud, distinct single or double {{Not a typo|cuk}} or {{Not a typo|turuck}};<ref name="Hancock"/> or ''{{Not a typo|kut}}'' and ''{{Not a typo|kut-kaaaoh}}''.<ref name="Ogden">Ogden JC, Thomas BT. 1985. A colonial wading bird survey in the central llanos of Venezuela. ''Colonial Waterbirds'' 8: 23–31</ref> These calls resemble the sound of a saxophone or toy trumpet.<ref name = "Ogden"/><ref name = "Van Perlo">Van Perlo B. 2009. ''A Field Guide to the Birds of Brazil''. OUP USA, First Edition</ref> Flight calls have been transcribed as a long drawn-out ''{{Not a typo|tuuut}}'',<ref name= "Van Perlo"/> as a ''{{Not a typo|cuk cuk cuk cuk}}''<ref name="Hancock"/> and as a loud nasal ''{{Not a typo|TUUR-DEE}}''. The male is believed to utter the ''{{Not a typo|TUUR}}'' element, and the female utters the following ''{{Not a typo|DEEE}}'' in response.<ref name="Hilty"/> The timbre of the ''{{Not a typo|TUUR-DEE}}'' call has earned it the local Spanish name {{Lang|es|Tarotaro}}.
The sharp-tailed ibis has a slow, laboured flight; with individuals flying low above the ground and often only covering short distances such as between neighbouring trees.<ref name="Hancock"/> However, they have been observed to fly across wide-open expanses of grassland toward roosting or feeding sites.<ref name="Hilty"/> Due to its noisy wing beating, it is often heard before coming into view.<ref name="Hilty"/>
==Distribution and habitat== The sharp-tailed ibis inhabits wet lowland savannas and riverbanks of northern South America east of the Andes, at less than 300-500m above sea level.<ref name="Hancock"/> It is native to Venezuela, eastern Colombia, southwestern Guyana, Brazil and Suriname. In Venezuela, it is typically found along or near the Orinoco and Apure rivers.<ref name="Blake"/><ref name = "Hancock"/> In the llanos of eastern Colombia, it is found along the Casanare and Cravo Sur rivers, as well as the Colombian stretch of the Apure.<ref name="Blake"/> In Brazil, it often occurs to the northwest of the Amazon<ref name="Hilty"/> and frequents the grasslands near to the Rio Negro and Rio Branco. However, it is also present to the west near Rio Guanco and to the south in northwest Mato Grosso.<ref name="Blake"/><ref name = "Hancock"/> This ibis also sometimes uses gallery forests in which to roost and breed.<ref name = "Hilty"/><ref name = "Aguliera">Aguilera E. 1988. La comunidad de ibises (Threskiornithidae) en los llanos de Venezuela. Sociedad de Ciencias Naturales La Salle 130.</ref>
This ibis is patchily distributed throughout its global range<ref name="Hancock"/><ref name="Birdlife" /> and despite a relatively large total population; it is generally uncommon on a local scale<ref name = "Thomas">Thomas BT. 1979. The birds of a ranch in the Venezuelan Llanos. Pp. 213–232 in Eisenberg JF. ''Vertebrate Ecology of the Northern Neotropics''. Smithsonian Institution Press, Washington D.C.</ref> and is considered to be the least numerous ibis species in the Venezuelan llanos.<ref name = "Hilty"/> It is however more abundant there during the rainy season.<ref name = "Aguliera"/>
It does not associate with other wading bird species, often distancing itself from its heterospecifics.<ref name = "Frederick">Frederick PC, Bildstein KL. 1992. Foraging ecology of seven species of Neotropical ibises (Threskiornithidae) during the dry season in the llanos of Venezuela. ''The Wilson Bulletin'' 104: 1–21.</ref> It is primarily found in male-female pairs and in small intraspecific groups comprising three to five individuals.<ref name="Morton">Morton ES. 1979. A comparative survey of avian social systems in northern Venezuelan habitats. Pp 233–259 in Eisenberg JF. ''Vertebrate Ecology of the Northern Neotropics''. Smithsonian Institution Press, Washington D.C.</ref> Despite this ibis's territoriality, individuals very rarely forage alone.<ref name="Frederick"/> The two individuals of a dyad differ markedly in body size, which suggests that they constitute a paired male and female given the differences in biometrics between the sexes.<ref name = "Blake"/> The groups of more than two individuals appear to comprise a paired male and female along with their juvenile offspring.<ref name="Hancock"/> In observations of flocks of three, the individual assumed to be the offspring is notably smaller with less developed facial colourations.<ref name="Luthin">Luthin CS. 1983. ''Breeding ecology of Neotropical ibises in Venezuela and comments on captive propagation''. Proceedings Jean DeLacour/IFCB Symposium on Breeding Birds in Captivity. International Foundation for the Conservation of Birds, Hollywood, California.</ref>
==Ecology==
===Food and feeding=== thumb|Sharp-tailed ibis foraging Like the sympatric glossy ibis, the sharp-tailed ibis largely feeds terrestrially or semi-terrestrially;<ref name="Frederick"/> either on open land or in short grass.<ref name="Kushlan">Kushlan JA, Morales G, Frohring PC. 1985. Foraging niche relations of wading birds in tropical wet savannas. ''Ornithological Monographs'' 36: 663–682.</ref> It typically forages in moist soil, shallow mud<ref name="Ogden"/> and along marshy edges of lagoons<ref name="Thomas"/> and rice fields.<ref name="Hilty"/> However, it also occasionally forages in shallow water at depths of 3 cm or less.<ref name="Hancock"/> It is less aquatic in its feeding habits than many other South American Ibises.<ref name="Frederick"/><ref name = "Kushlan"/> Throughout the sharp-tailed ibis's range, only the buff-necked ibis forages on drier, higher-altitude ground.<ref name="Ogden"/> More rarely, the sharp-tailed ibis has been observed to forage in gallery forests during the wet season.<ref name="Luthin"/>
The species primarily feeds tactilely. Its typical foraging method consists in walking quickly over moist soil and through shallow mud or water; probing deeply into the moist underlying substrate for prey at intervals.<ref name = "Hancock"/><ref name="Kushlan"/> It is relatively flexible in microhabitat use, foraging either on open ground or in short grass.<ref name="Kushlan"/> Several individuals have been observed with dried mud along the length of their bills.<ref name="Ogden"/> Its foraging highly resembles that of the glossy ibis and buffnecked ibis.<ref name = "Kushlan"/> Despite the largely overlapping niches, the sharp-tailed ibis may be more active during the morning than other sympatric ibises; hence suggesting temporal niche partitioning.<ref name = "Frederick"/> There may also be differences between these sympatric ibis species in specific dry-season probing depths and microhabitat use within the large-scale savannas.<ref name = "Ogden"/>
The sharp-tailed ibis feeds primarily on medium-sized insects,<ref name = "Kushlan"/> especially in the dry season.<ref name="Frederick"/> It also occasionally feeds on amphibians, crustaceans, earthworms and snails.<ref name="Matheu">Matheu E, del Hoyo J, Garcia EFJ, Boesman P. 2016. Sharp-tailed ibis (Cercibis oxycerca). In: del Hoyo J, Elliot A, Sargatal J, Christie DA, de Juana E. ''Handbook of the birds of the World Alive'': Lynx Edicions, Barcelona (retrieved from http://www.hbw.com/node/52770 on 21 July 2016).</ref> Its tendency to forage in pairs or small groups may be partly attributable to the relatively dispersed distribution of its insect prey in the llanos.<ref name="Morton"/>
This ibis probably migrates locally during the wet season to higher altitude feeding grounds which may serve as a refuge from the extensive flooding of the lowland grassland.<ref name="Kushlan"/> Its persistence as a primarily terrestrial forager in its semi-aquatic habitat suggests that its relatively dry higher-altitude feeding grounds which remain unflooded in the wet season are sufficiently extensive, or that the dry season is sufficiently long to ensure high annual prey availability in the lowlands.<ref name="Kushlan"/>
===Breeding=== Unusually for a wading bird of the llanos, this ibis breeds in the dry season months from August until February;<ref name ="Aguliera"/><ref name="Morton"/> whereas the majority of llanos avifauna breeds in the wet season around May to October.<ref name="Morton"/> The sharp-tailed ibis breeds solitarily in gallery forests, where egg-laying is believed to occur from August to September; and fledged offspring remain with their parents until late February.<ref name="Aguliera"/> Average egg measurements have been reported as 65.9 x 44mm and the average egg weight as 70g.<ref>Schönwetter M. 1967. Handbuch der Oologie (W. Meise, ed) Band I. Akademie – Verlag, Berlin.</ref> In a six-year wading bird survey of Masaguaral in the llanos, the sharp-tailed ibis was never seen on the lowland grasslands during the dry-season months of August and December.<ref name = "Thomas"/> In one other study, it was not sighted in the months of December and January.<ref name="Aguliera"/> Its secretive nesting behaviours probably explains its apparent absence from the open llanos grasslands during the breeding season. Details of courtship in this species are largely unknown.<ref name="Hancock"/> However, preening behaviours between mates have been observed in which one individual nibbles with its bill at the base of the other's bill;<ref name = "Ogden"/> which could potentially be part of courtship.<ref name = "Hancock"/> Additionally, larger individuals have been observed to preen smaller individuals assumed to be their offspring, which also sometimes gently peck with their bills at the larger individuals in return.<ref name="Frederick"/>
==Threats and survival== One natural enemy of this ibis may be the black-collared hawk ''Busarellus nigricollis'', one individual of which was once seen pursuing a sharp-tailed ibis over a flooded marsh. Further, the ibis flew with a rapid twisting flight which was unusual considering its normally torpid wing beating.<ref name = "Ogden"/>
==Relationship to humans== This ibis has thus far not been kept in captivity in zoological institutions;<ref>Archibald GW, Lantis SDH, Lantis LR, Munetchika I. 1980. Endangered ibises Threskiornithae: their future in the wild and in captivity. ''International Year Zoobook'' 20: 6–17.</ref><ref>Brouwer K, Schrifter H, Jones ML. 1994. Longevity and breeding records of ibises and spoonbills Threskiornithidae in captivity. ''International Zoo Yearbook'' 33: 94–102.</ref> nor has it ever been reported to have been imported to countries outside its range in South America.<ref>Delacour J. 1931. Herons, storks, spoonbills and ibises. ''Aviculture'' 3: 772–778.</ref>
==Status== Despite this ibis's infrequent occurrence in its savannah habitat, the population appears to have remained stable since the early 20th century;<ref name="Byers">Byers O, Brouwer K, Coulter M, Seal US. 1995. Stork, Ibis and Spoonbill Conservation Assignment Management Plan: Working Document. IUCN/SSC Conservation Breeding Specialist Group: Apple Valley, MN.</ref> There have been no trade records of this species, and the global population is not considered to be threatened generally.<ref name="Matheu"/><ref name="Byers"/> The world population has been estimated at 10,000–25,000 individuals,<ref name="Birdlife">{{cite iucn |author=BirdLife International |date=2016 |title=''Theristicus caerulescens'' |volume=2016 |article-number=e.T22697435A93613867 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22697435A93613867.en |access-date=14 November 2021}}</ref><ref name="Byers"/> with 6700-17000 of these being mature.<ref name="Birdlife"/> The sharp-tailed ibis has been evaluated by the IUCN as Least Concern since 2004 because this bird does not approach Vulnerable under the population trend and range size criteria.<ref name="Birdlife"/> Nevertheless, this species could potentially decline unnoticed due to its solitary lifestyle and hence the potential difficulty in detecting individuals during population monitoring.<ref name="Hancock"/> Further information on its basic biology and ecology is required to safeguard it against appreciable future population declines.<ref name="Hancock"/>
==References== {{Reflist}}
{{Threskiornithidae}} {{Pelecaniformes genera|A.|state=collapsed}} {{Taxonbar|from=Q737454}}
sharp-tailed ibis Category:Birds of Colombia Category:Birds of Venezuela Category:Birds of the Guiana Shield sharp-tailed ibis Category:Ibises Category:Taxonomy articles created by Polbot