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Icterus icterustroupial

By Corey Carter

Geographic Range

Troupials are New World orioles found in northern and central South America. There are three subspecies occupying distinct ranges.

Icterus icterus icterus inhabits the Llanos region in northeastern Colombia and the area between the coast and Amazonas and from Carabobo to Sucre in Venezuela.

Icterus icterus metae is found in the province of Arauca in northwestern Columbia as well as in the Venezuelan state of Apure near the Meta river, after which the subspecies was named.

Icterus icterus ridgwayi inhabits a range from the northeastern tip of Colombia to northwestern Venezuela, and between the coast and Falcón and Lara. Icterus icterus ridgwayi is also found on the islands of Aruba, Curaçao, and Isla Margarita. They have been introduced to the islands of Puerto Rico, St. Thomas, and Bonaire.

While the earlier literature regards troupials as a species or superspecies, with six subspecies, a more recent publication by James Clements, (Supplement to "Birds of the World: A Checklist") states that troupials are a complex of three species with several races each. The three species are: Venezuelan troupials, Icterus icterus, with subspecies I. i. ridgwayi, I. i. icterus, and I. i. metae, Campo troupials, Icterus jamaicaii (previously I. i. jamaicaii), and orange-backed troupials, Icterus croconotus (previously I. i. croconotus), with subspecies I. c. croconotus and I. c. strictifrons. These conclusions are based on recent phylogenetic work by Jaramillo et al. (1999) and Omland et. al. (1999). (Burke and Jaramillo, 1999; Clements, 2003; Omland, et al., 1999; Ridgely and Tudor, 1989)

Habitat

Troupials prefer dry edge habitats to those with heavy rainfall, and are typically found in areas of semi-open savanna, dry woodlands, llanos, arid scrub, or gallery forests. Troupials also frequent fruit plantations and gardens with fruit and flowers. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

  • Range elevation
    0 to 500 m
    0.00 to 1640.42 ft

Physical Description

Troupials are large birds with lengthy, wedge-shaped tails, and long, chisel-like bills. The juvenile plumage is much like adult plumage except for a duller orange color, and a hint of brown on the black feathers. Additionally the naked skin around the eye is a dull blue-grey color instead of the bright blue skin of the adults. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

Icterus icterus metae has less black on the back of the body than the other subspecies. The orange neck collar extends further up the back of the head to the hind crown as well as a little further down the nape. Some orange color also extends up the back from the rump, giving the appearance of a patch of orange on the lower back when the wings are closed. Additionally, a band of black bisects the white line running lengthwise down the middle of the closed wing. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

Icterus icterus ridgwayi has a similar plumage color pattern to that of I. i. icterus, but differs in that it has a larger build with sturdy legs, and a longer, bulkier bill. Icterus icterus ridgwayi is a darker shade of orange on the island of Aruba compared to individuals from Curaçao. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

Adult plumage of I. icterus (including I. i. icterus) is largely black and orange with the exception of the grey lower mandible. The black coloration starts at the entirely black head and on the top of the bill and extends to cover the entire neck and the upper portion of the breast. The underparts of the bird are orange from the belly to the feathers on the underside of the tail. Icterus icterus icterus also has an orange neck collar, separating the head from the back. The back and shoulders are black, and an orange-yellow color stretches down over the lower back, rump and upper tail coverts. The wings are mostly black with a patch of orange feathers (epaulet) on the upper extreme of the shoulder and a white band running lengthwise in a closed position. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

The immature plumage is similar in pattern to that of mature adults, except for a few remaining worn out juvenile feathers. The contrast of worn and fresh feathers is most noticeable at the base of the wing when the wings are in an open position. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

  • Sexual Dimorphism
  • sexes alike

Reproduction

Males sing to establish territory. Troupials form monogamous pairs that reportedly stay together throughout the year. (Burke and Jaramillo, 1999)

Nesting season varies by location, lasting from March to September throughout most of their South American range, May to June in Venezuela, and throughout the year in the Antilles. Troupials are well known as nest pirates, seeking and seizing the covered, hanging stick nests of common thornbirds (Phacellodomus rufifrons) or great kiskadees (Pitangus sulphuratus). As an obligate nest pirate they are one of very few bird species that build no nest of their own. They use their stolen nests for breeding and both members of the breeding pair use individual nests as sleeping chambers. Troupials ultimately use one nest to raise the young. They usually have a clutch size of three eggs, which are white or a whitish pink color with dark spots around the bottom. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

  • Breeding interval
    Breeding occurs throughout the year in some parts of the range, and seasonally in other parts of the range. Between clutch intervals are not reported.
  • Breeding season
    Breeding occurs from March through September in South America, except in Venezuela, which is May through June; believed to breed year-round in the Antilles.
  • Average eggs per season
    3
  • Range time to hatching
    15 to 16 days
  • Range fledging age
    21 to 23 days

The eggs are incubated for 15 or 16 days and newly hatched troupials are fed equally by both parents. Hatchlings stay in the nest for about 21 to 23 days, during which time they may fall victim to bot flies. After the nesting period, fledglings travel and forage with their parents, and roost in a stolen nest of their own. (Burke and Jaramillo, 1999)

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

Lifespan/Longevity

There is no information on the average lifespan of troupials.

Behavior

Troupials steal the nests of other birds and are capable of violent attacks against defending nest residents. They tend to prefer lower nests to those higher in a tree and they may feed on any eggs and nestlings left behind. After obtaining a nest, troupials make modifications like adding their own nest lining or making a wider entrance. A mated pair typically uses more than one nest. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

  • Average territory size
    430,000 km^2

Home Range

There is little information about the home range of troupials, although year round territories may be common in tropical orioles.

Communication and Perception

Male troupials are best known for singing. They sing most ardently in the early morning hours and continue throughout the day, while females sing less often, often in response to a male's song (Jaramillo and Burke 1999). Despite this difference between the sexes, female song may be common in troupial orioles (J. Price, N. Freidman, K. Omland, unpublished data). Both sexes raise their neck feathers while singing. (Burke and Jaramillo, 1999)

Troupials have a simple song consisting of loud, long, repetitive notes, which resemble the call of Baltimore orioles (Icterus galbula). Recent research suggests that this similarity of song is due to convergent evolution (Price et al. 2007). Troupial song is difficult to identify in that the simple notes seem to meld together in their slow, careful progression. The song has 2 to 3 individual notes within each repeated phrase and the notes themselves are hoarse whistles of a high or low pitch. (Burke and Jaramillo, 1999; Ridgely and Tudor, 1989)

Food Habits

Troupials forage as mated pairs or as a family, consisting of the mated pair and their fledglings. Whether in a pair or as a family group, troupials seldom forage in the vicinity of large flocks. Throughout the breeding season troupials forage for insects in trees and low bushes. On tropical islands, they forage along the ground for fallen fruit. During the non-breeding season, troupials in some areas consume fruit. The fruit of giant cacti for example, may make up the entire diet of troupials when in season. Other fruits eaten include: mango (Mangifera indica), kenepa (Melicoccus bijugatus), sapodilla (Achras zapota), soursop (Ammona muricata), papaya (Carica papaya), dates (Phonix dactylifera), and malphighia cherries (Malphigia). Troupials have also been observed feeding at bird feeders, in gardens with fruit trees, and at fruit plantations. (Jaramillo and Burke 1999; Ridgely and Tudor 1989)

  • Animal Foods
  • insects
  • Plant Foods
  • fruit

Predation

Nestlings are often parasitized by bot flies (Oestridae), which can be fatal for these developing young. Adults are most likely to be killed by larger birds like falcons and accipiter hawks. (Burke and Jaramillo, 1999)

Ecosystem Roles

Troupials consume fruit and insects, facilitating seed dispersal and helping control insect populations. They are nest pirates, stealing the nests of common thornbirds (Phacellodomus rufifrons) or great kiskadees (Pitangus sulphuratus). (Burke and Jaramillo, 1999)

  • Ecosystem Impact
  • disperses seeds
  • pollinates
Species Used as Host
  • common thornbirds (Phacellodomus rufifrons)
  • great kiskadees (Pitangus sulphuratus)
Commensal/Parasitic Species

Economic Importance for Humans: Positive

As the national bird of Venezuela, troupials promote tourism and national pride. They are kept as cage birds and are often sold throughout their range. They are also valuable research subjects. (Ridgely and Tudor, 1989)

Economic Importance for Humans: Negative

Troupials are known pests on fruit plantations, damaging and devouring valuable crops.

  • Negative Impacts
  • crop pest

Conservation Status

Troupials face few threats, although they have experienced some population decrease as a result of domestication as a cage bird. In general, they have a very low risk of extinction, especially in Venezuela where they are protected as the national bird. (Ridgely and Tudor, 1989)

Other Comments

Of all the species in the genus Icterus genus, troupials are unique. They are larger than average orioles and have some other morphological and behavioral differences as well. First, eye color is different in that troupials have bright yellow eyes whereas the majority of orioles have dark brown eyes. Even more unique is the patch of naked, blue skin surrounding the eye, shared with only a small number of species. The troupial group (I. icterus and I. jamacaii) is known to pirate the nests of other birds, and troupials have one of the strongest beaks of any oriole. (Burke and Jaramillo, 1999; Freeman and Zink, 1995; Monroe and Sibley, 1993; Omland, et al., 1999; Ridgely and Tudor, 1989)

Troupial songs set them apart from other orioles because of its bland, two-note simplicity. Unlike other orioles, whose songs are generally recognizable, troupials have a sequence of notes that blend together, making it hard to distinguish separate phrases (Jaramillo and Burke, 1999; Nick Friedman, personal obs.). Troupials have a shaggy bib, a border of pointed feathers around the top of the breast that is smooth on other orioles (Jaramillo and Burke, 1999). In addition, troupials are one of only a few orioles that do not exhibit delayed plumage maturation (DPM) (Kevin Omland, Frode Jacobsen, personal obs.). This means that yearling male troupials have plumage that is the same or very similar to that of adult males. In species that do exhibit DPM, yearling male plumage normally resembles that of adult females. This phenomenon is in fact exaggerated in troupials because the species is monochromatic (males and females have similar bright plumage colors and patterns), as is typical of tropical orioles (Omland and Hofmann 2006). (Burke and Jaramillo, 1999)

According to research published by Freeman and Zink (1995), troupials should not be considered members of Icterus. In fact, when Freeman and Zink constructed a phylogenetic tree illustrating the estimated genetic relatedness of 47 species within the subfamily Icterinae, they found that troupials were not members of the oriole clade but an outgroup on their tree, suggesting a distant relationship. (Freeman and Zink, 1995)

When Omland, Lanyon, and Fritz conducted a follow up genetic investigation in 1999 they found troupials to be more closely related to other orioles. Their phylogenetic tree placed troupials as part of the genus Icterus. Freeman and Zink may have used a contaminated sample. (Omland, et al., 1999)

One further difficulty with troupials, is in defining the species limits. The "troupial group" includes six proposed subspecies: I. i. croconotus, I. i. jamaicaii, I. i. icterus, I. i. metae, and I. i. ridgwayi. Over the years these forms have alternately been re-classified as subspecies and full species. A phylogenetic tree constructed by Omland, Lanyon, and Fritz demonstrates that these subspecies are closely related. According to Monroe and Sibley’s “A World Checklist of Birds,” the name “troupial” only applies to Icterus icterus. This classification most likely includes I. i. icterus, I. i. metae, and I. i. ridgwayi as subspecies. Furthermore Monroe and Sibley group I. i. croconotus and I. i. jamacaii as subspecies under the name Campo oriole. Most recently I. i. jamaicaii, I. i. croconotus, and I. i. strictifrons were recognized as species. (Clements, 2003; Monroe and Sibley, 1993; Omland, et al., 1999; Ridgely and Tudor, 1989)

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

agricultural

living in landscapes dominated by human agriculture.

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.

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.

fertilization

union of egg and spermatozoan

forest

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

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.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

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

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

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

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

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

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

Clements, J. 2003. "Supplement to Birds of the World" (On-line). Accessed May 08, 2007 at http://www.ibispub.com/updates.html.

Ekstrom, J., S. Butchart. 2000. "IUCN Red List of Threatened Species" (On-line). Accessed March 01, 2007 at http://www.iucnredlist.org/search/details.php/54128/summ.

Freeman, S., R. Zink. 1995. A Phylogenetic Study of the Blackbirds Based On Variation in Mitochondrial DNA Restriction Sites. Systematic Biology, 44: 409-420.

Monroe, B., C. Sibley. 1993. A World Checklist of Birds. Ann Arbor, Michigan: Edwards Brothers, Inc..

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, 12/2: 224-239.

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

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