The sharp-tailed ibis (''Cercibis oxycerca'') is a species of
ibis
The ibises () (collective plural ibis; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae, that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word f ...
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''.
[Blake ER. 1977. ''Manual of Neotropical Birds'', vol I. University of Chicago Press, Chicago.] Much remains unknown about this ibis's evolutionary history;
[Hancock JA, Kushlan JA, Kahl MP. 1992. ''Storks, Ibises and Spoonbills of the World''. Academic Press.] however,
phylogenetic analyses
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
based on skull morphology and function suggest that it is closely related to the
spoonbill
Spoonbills are a genus, ''Platalea'', of large, long-legged wading birds. The spoonbills have a global distribution, being found on every continent except Antarctica. The genus name ''Platalea'' derives from Ancient Greek and means "broad", refe ...
s.
Description
This large ibis measures 75–86 cm in length, with males being slightly larger than females.
In adult males, the flat wing measures 390–415mm lengthways, and the
culmen measures 156–168mm from the base of the bill.
In adult females, the wing is 376–413mm long and the culmen 144–197mm.
The species is distinguished by its notably long tail, the longest among all extant ibis species;
[Van Perlo B. 2009. ''A Field Guide to the Birds of Brazil''. OUP USA, First Edition.] measuring 250–301mm in males and 256–272mm in females.
The tail projects beyond the tips of the folded wings when the ibis stands; and beyond the trailing legs in flight.
The
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, ...
is predominantly black with greenish glossing;
and with purplish tinges on the upper back, hindneck, wings and tail.
The forehead and cheek region are occasionally greyish brown.
Juveniles appear similar to adults, but their plumage lacks a metallic sheen.
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
Crest or CREST may refer to:
Buildings
*The Crest (Huntington, New York), a historic house in Suffolk County, New York
*"The Crest", an alternate name for 63 Wall Street, in Manhattan, New York
*Crest Castle (Château Du Crest), Jussy, Switzerla ...
extends down the back of its head and upper neck. The
iris
Iris most often refers to:
*Iris (anatomy), part of the eye
*Iris (mythology), a Greek goddess
* ''Iris'' (plant), a genus of flowering plants
* Iris (color), an ambiguous color term
Iris or IRIS may also refer to:
Arts and media
Fictional ent ...
is greyish red, but is sometimes scarlet red, which may be associated with breeding.
Nothing is however known of changes in soft part colourations as part of
courtship
Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...
.
Overall, the sharp-tailed ibis is superficially similar to many
sympatric
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...
ibises such as the
glossy ibis
The glossy ibis (''Plegadis falcinellus'') is a water bird in the order Pelecaniformes and the ibis and spoonbill family Threskiornithidae. The scientific name derives from Ancient Greek ''plegados'' and Latin, ''falcis'', both meaning "sickle" a ...
and the
bare-faced ibis
The bare-faced ibis (''Phimosus infuscatus''), also known as the whispering ibis, is a species of bird in the family Threskiornithidae, in the monotypic genus ''Phimosus''.
Distribution
It is found in Argentina, Bolivia, Brazil, Colombia, Ecua ...
;
[Hilty SL. 2002. ''Birds of Venezuela''. Princeton University Press. 2nd Edition.] but clearly differs through its longer tail and larger body size.
This ibis is particularly vocal. The call is a loud, distinct single or double or ;
or ' and '.
[Ogden JC, Thomas BT. 1985. A colonial wading bird survey in the central llanos of Venezuela. ''Colonial Waterbirds'' 8: 23–31] These calls resemble the sound of a saxophone or toy trumpet.
[Van Perlo B. 2009. ''A Field Guide to the Birds of Brazil''. OUP USA, First Edition] Flight call Flight calls are vocalisations made by 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 fou ...
s have been transcribed as a long drawn-out ',
as a '
and as a loud nasal '. The male is believed to utter the ' element, and the female utters the following ' in response.
The timbre of the ' call has earned it the local Spanish name .
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.
However, they have been observed to fly across wide-open expanses of grassland toward roosting or feeding sites.
Due to its noisy wing beating, it is often heard before coming into view.
Distribution and habitat
The sharp-tailed ibis inhabits wet lowland savannas and riverbanks of northern South America east of the
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
, at less than 300-500m above sea level.
It is native to
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
, eastern
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
, southwestern
Guyana
Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...
,
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
and
Suriname
Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...
. In Venezuela, it is typically found along or near the
Orinoco
The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...
and
Apure
Apure State ( es, Estado Apure, ) is one of the 23 states of Venezuela. Its territory formed part of the provinces of Mérida, Maracaibo, and Barinas, in accordance with successive territorial ordinations pronounced by the colonial author ...
rivers.
In the
llanos
The Llanos (Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, sav ...
of eastern Colombia, it is found along the
Casanare and
Cravo Sur rivers, as well as the Colombian stretch of the Apure.
In Brazil, it often occurs to the northwest of the Amazon
and frequents the grasslands near to the
Rio Negro and
Rio Branco. However, it is also present to the west near
Rio Guanco
Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil.
Rio or Río may also refer to:
Geography Brazil
* Rio de Janeiro
* Rio do Sul, a ...
and to the south in northwest
Mato Grosso
Mato Grosso ( – lit. "Thick Bush") is one of the states of Brazil, the third largest by area, located in the Central-West region. The state has 1.66% of the Brazilian population and is responsible for 1.9% of the Brazilian GDP.
Neighboring ...
.
This ibis also sometimes uses
gallery forest
A gallery forest is one formed as a corridor along rivers or wetlands, projecting into landscapes that are otherwise only sparsely treed such as savannas, grasslands, or deserts. The gallery forest maintains a more temperate microclimate above th ...
s in which to roost and breed.
[Aguilera E. 1988. La comunidad de ibises (Threskiornithidae) en los llanos de Venezuela. Sociedad de Ciencias Naturales La Salle 130.]
This ibis is patchily distributed throughout its global range
and despite a relatively large total population; it is generally uncommon on a local scale
[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.] and is considered to be the least numerous ibis species in the Venezuelan llanos.
It is however more abundant there during the rainy season.
It does not associate with other wading bird species, often distancing itself from its heterospecifics.
[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.] It is primarily found in male-female pairs and in small intraspecific groups comprising three to five individuals.
[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.] Despite this ibis's territoriality, individuals very rarely forage alone.
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.
The groups of more than two individuals appear to comprise a paired male and female along with their juvenile offspring.
In observations of flocks of three, the individual assumed to be the offspring is notably smaller with less developed facial colourations.
[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.]
Ecology
Food and feeding
![Sharp-tailed Ibis - Venezuela 90Image23 (15418279502) (2)](https://upload.wikimedia.org/wikipedia/commons/3/3a/Sharp-tailed_Ibis_-_Venezuela_90Image23_%2815418279502%29_%282%29.jpg)
Like the sympatric glossy ibis, the sharp-tailed ibis largely feeds terrestrially or semi-terrestrially;
either on open land or in short grass.
[Kushlan JA, Morales G, Frohring PC. 1985. Foraging niche relations of wading birds in tropical wet savannas. ''Ornithological Monographs'' 36: 663–682.] It typically forages in moist soil, shallow mud
and along marshy edges of lagoons
and rice fields.
However, it also occasionally forages in shallow water at depths of 3 cm or less.
It is less aquatic in its feeding habits than many other South American Ibises.
Throughout the sharp-tailed ibis's range, only the
buff-necked ibis
The buff-necked ibis (''Theristicus caudatus''), also known as the white-throated ibis, is a fairly large ibis found widely in open habitats of eastern and northern South America. It formerly included the similar black-faced ibis as a subspecies ...
forages on drier, higher-altitude ground.
More rarely, the sharp-tailed ibis has been observed to forage in gallery forests during the wet season.
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.
It is relatively flexible in microhabitat use, foraging either on open ground or in short grass.
Several individuals have been observed with dried mud along the length of their bills.
Its foraging highly resembles that of the glossy ibis and buffnecked ibis.
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.
There may also be differences between these sympatric ibis species in specific dry-season probing depths and microhabitat use within the large-scale savannas.
The sharp-tailed ibis feeds primarily on medium-sized insects,
especially in the dry season.
It also occasionally feeds on amphibians, crustaceans, earthworms and snails.
[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).] 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.
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.
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.
Breeding
Unusually for a wading bird of the llanos, this ibis breeds in the dry season months from August until February;
whereas the majority of llanos avifauna breeds in the wet season around May to October.
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.
Average egg measurements have been reported as 65.9 x 44mm and the average egg weight as 70g. 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.
In one other study, it was not sighted in the months of December and January.
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.
However, preening behaviours between mates have been observed in which one individual nibbles with its bill at the base of the other's bill;
which could potentially be part of courtship.
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.
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.
Relationship to humans
This ibis has thus far not been kept in captivity in zoological institutions; nor has it ever been reported to have been imported to countries outside its range in South America.
[Delacour J. 1931. Herons, storks, spoonbills and ibises. ''Aviculture'' 3: 772–778.]
Status
Despite this ibis's infrequent occurrence in its savannah habitat, the population appears to have remained stable since the early 20th century;
[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.] There have been no trade records of this species, and the global population is not considered to be threatened generally.
The world population has been estimated at 10,000–25,000 individuals,
with 6700-17000 of these being mature.
The sharp-tailed ibis has been evaluated by the
IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
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 ...
since 2004 because this bird does not approach
Vulnerable under the population trend and range size criteria.
Nevertheless, this species could potentially decline unnoticed due to its solitary lifestyle and hence the potential difficulty in detecting individuals during population monitoring.
Further information on its basic biology and ecology is required to safeguard it against appreciable future population declines.
References
{{Taxonbar, from=Q737454
sharp-tailed ibis
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 ...
Birds of Colombia
Birds of Venezuela
Birds of the Guianas
sharp-tailed ibis
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 ...
Taxonomy articles created by Polbot