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Icterus cayanensisepaulet oriole

By Corey Carter

Geographic Range

Epaulet orioles are distributed widely throughout the central and eastern portions of South America. Each of the five subspecies of Icterus cayanensis inhabit a different area.

For I. c. cayanensis, the range covers the Amazon basin and its borders stretching from the Guianas, excluding the coastal plains, to northeast Brazil, south to Beni in Bolivia, and east to Peru.

Icterus cayanensis tibialis has a range within eastern Brazil from Maranhao, east through Piauí and Ceará, and south through Pernambuco, Bahia, Espirito Santo, and Rio de Janeiro.

The range of I. c. valenciobuenoi is outlined by south Goias, west Minas Gerais, west Sao Paulo, and southeast Mato Grosso.

Icterus cayanensis periporphyrus is found from northern and central Bolivia to western central Mato Grosso.

Icterus cayanensis pyrrhopterus has a range that stretches from central Bolivia east to Parana in Brazil, and as far south as Buenos Aires in Argentina.

Although formerly considered conspecific, Icterus chrysocephalus (Moriche orioles) is now generally considered a distinct species. Mitochondrial DNA sequence analysis indicates that all these taxa are very closely related (Omland et al. 1999). ("Wikipedia Moriche Oriole", 2008; Jaramillo and Burke, 1999; Omland, et al., 1999; Ridgley and Tudor, 1989)

Habitat

Epaulet orioles generally can be found in edge and open forests, as well as woodlands. They have been observed in open forests, forest borders, savannas, palm savanna, deciduous woodlands, gallery forest, urban gardens, cerrado woodlands, chaco woodlands, and clearings. They also inhabit both humid and dry areas of their habitat. They prefer open woodlands with sandy ground in Surinam, and frequent the dense forests of the Andean foothills in Bolivia. (Jaramillo and Burke, 1999; Ridgley and Tudor, 1989)

  • Range elevation
    0 to 1000 m
    0.00 to 3280.84 ft

Physical Description

Epaulet orioles have very little color on their bodies, with an all black body and a dash of yellow or chestnut on the shoulders. Their body shape is slender with a thin, lengthy, rounded tail and a thin bill that varies in length and curve based on location. The lack of color in the plumage makes it easy to distinguish epaulet orioles from other orioles and difficult to distinguish them from blackbirds. Yellow-shouldered epaulet orioles (I. c. tibialis) have yellow color on the lining of the wing and the chestnut shouldered epaulet orioles (I. c. pyrrhopterus) may appear completely black from a distance. In adult males the bill is pointed without any curve and the eyes are dark brown to dark reddish brown. Below the eye is slightly grey and the wing linings are black. The back is also all black, lacking any indication of a pattern. Female epaulet orioles closely resemble males. Juvenile birds resemble adults but their colors are more muted.

Icterus cayanensis cayanensis, also known as Cayanensis orioles, have yellow on the shoulders and black running along the tip of the yellow wing lining. One regional variation has yellow lining to the thighs, which are typically black. This variation is thought to be independent of the influence of the other subspecies because of its geographical distance from them.

Icterus cayanensis tibialis, yellow shouldered or yellow thighed orioles, have a yellow shoulder similar to I. c. cayanensis. Some have yellow wing lining and thigh color (as opposed to black). This is not true everywhere, populations in the north tend to have yellow on the thighs, those in the south have black thighs and dusky wings similar to I. c. valenciobuenoi. They also have a shorter bill and smaller body than I. c. cayanensis.

Icterus cayanensis valenciobuenoi, Valencio Bueno’s oriole has a dusky wing lining with yellow tip, and black thighs. The shoulder is an ochre-orange, slightly paler than that of the I. c. periporphyrus. It is said to be an intermediate between the yellow shouldered, northern subspecies, and the tawny/chestnut shouldered southern forms.

Icterus cayanensis periporphyrus, tawny shouldered oriole, is similar to I. c. pyrrhopterus, except that it is slightly paler. This subspecies has a smaller, thinner bill, the underwings and thighs are black and the wings are tawny or cinnamon.

Icterus cayanensis pyrrhopterus, chestnut shouldered oriole, is the darkest of the subspecies and can sometimes appear almost completely black. The wing lining is black and the shoulder is chestnut. The chestnut coloration may be caused by the same "phaomelanin" coloration found in North American orchard orioles (Icterus spurius) (Hofmann, Cronin and Omland, 2007). (Hofmann, et al., 2007; Jaramillo and Burke, 1999; Ridgley and Tudor, 1989)

  • Sexual Dimorphism
  • sexes alike

Reproduction

In the breeding season, males searching for mates perch high in the trees to sing, occasionally joined by females. No other mating displays or behaviors have been observed. Epaulet orioles are likely to be socially monogamous.

Epaulet orioles of Brazil, Paraguay, Uruguay, and Argentina breed between the months of October and December. Shiny cowbirds parasitize nests of epaulet orioles in Brazil and Argentina, but successful fledging of shiny cowbird young from epaulet oriole nests has not been observed. General features of reproduction in epaulet orioles are not documented. One brood per year is typical, although multiple broods may be attempted. Young are likely to fledge 10 to 20 days after hatching and sexual maturity is probably achieved in the year after hatching.

  • Breeding interval
    Likely one breeding season per year, but number of broods could be 1 or more.
  • Breeding season
    In Brazil, Paraguay, Uruguay, and Argentina they breed between the months of October and December.
  • Range fledging age
    10 to 20 days
  • Range age at sexual or reproductive maturity (female)
    1 (low) years
  • Range age at sexual or reproductive maturity (male)
    1 (low) years

There is little documented information on hatchling care in epaulet orioles. In most other Icterus species both males and females contribute to caring for hatchlings.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

There is no information on lifespan in epaulet orioles. Other Icterus species live up to 12 years in the wild.

Behavior

Epaulet orioles are quiet but active. They have been observed alone and in pairs, although their counterparts in Bolivia may sometimes join mixed canopy flocks. They eat insects as well as fruit and nectar and they typically forage around the top to middle areas of trees. They are known to hang from vines and jerk their tail fretfully as they forage. (Jaramillo and Burke, 1999)

  • Range territory size
    not known (low) cm^2

Home Range

Home range sizes are not documented.

Communication and Perception

Like other birds, epaulet orioles use primarily visual and acoustic cues for communication and navigating their environment. Males sing to attract females and advertise territorial boundaries.

Food Habits

Epaulet orioles eat insects, fruit, and the nectar of flowers.

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit
  • nectar

Predation

Adults are likely attacked by Accipter hawks. Eggs and nestlings are likely to be preyed on by a variety of birds, snakes, lizards, and mammals. However, specific information on predation is not reported in the literature.

Ecosystem Roles

There is little published information on ecosystem roles. Epaulet orioles are likely to disperse seeds of fruit trees, pollinate fruiting trees, and impact insect populations through predation. Shiny cowbirds (Molothrus bonariensis) parasitize their nests.

  • Ecosystem Impact
  • disperses seeds
  • pollinates
Commensal/Parasitic Species

Economic Importance for Humans: Positive

There is little available documentation of positive economic impacts on humans. Epaulet orioles are likely to play a role as pollinators. They can also impact ecotourism as this species is endemic to relatively few countries in South America.

  • Positive Impacts
  • ecotourism
  • pollinates crops
  • controls pest population

Economic Importance for Humans: Negative

There is no documentation of negative impacts on humans. Populations may cause minor damage to fruit crops.

Conservation Status

Epaulet orioles are widely distributed. However, individual subspecies could become threatened in the future as a result of habitat destruction.

Other Comments

This species is quite different from North American Icterus in that juveniles and yearlings lack a distinct pattern in their first year. Yearling epaulet orioles have a muted version of the adult color pattern (K. Omland, personal observation). Males and females are predominantly jet black as adults, with different patches of color depending upon subspecies (Jaramillo and Burke, 1999).

The Icterus cayanensis complex is closely related to another South American oriole species, Icterus auricapillus, orange-crowned orioles (Omland et al. 1999). This whole group likely colonized South America from the Caribbean islands (Omland et al. 1999; Sturge, Omland et al. submitted). (Jaramillo and Burke, 1999; Omland, et al., 1999)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Corey Carter (author), University of Maryland, Baltimore County, Kevin Omland (editor, instructor), University of Maryland, Baltimore County.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nectarivore

an animal that mainly eats nectar from flowers

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

2008. "Wikipedia Moriche Oriole" (On-line). Accessed April 05, 2008 at http://en.wikipedia.org/wiki/Moriche_Oriole.

Hofmann, C., T. Cronin, K. Omland. 2007. Melanin coloration in New World orioles II: ancestral state reconstruction reveals lability in the use of carotenoids and phaeomelanins.. Journal of Avian Biology, 38: 172-181.

Jaramillo, A., P. Burke. 1999. New World Blackbirds: The Icterids. Princeton, NJ: Princeton University Press.

Omland, K., S. Lanyon, S. Fritz. 1999. A molecular phylogeny of the New World orioles (Icterus): the importance of dense taxon sampling.. Molecular Phylogenetics and Evolution, 12: 224-239.

Ridgley, R., G. Tudor. 1989. The Birds of South America: Volume 1: The Oscine Passerines. Austin, TX: University of Texas Press.

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