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Icterus pectoralisspot-breasted oriole(Also: spotted-breasted oriole)

By Ian Realo

Geographic Range

Spot-breasted orioles are found down the Pacific Coast of Mexico and Central America, reaching from southern Mexico to Costa Rica. Found at a range of altitudes, from below 500 m in Mexico and Costa Rica, and up to 1500 m in El Salvador and Honduras. There are four recognized subspecies of spot-breasted orioles. The I. p. carolynae subspecies is native to southern Mexico, Pacific Coast of Guerrero and Oaxaca. I. p. pectoralis is native to southeast Mexico and east Oaxaca, central Chiapas south to Tonalá. The I. p. guttulatus subspecies is native to southeast Mexico south to arid valleys of Guatemala, Honduras, and northwestern Nicaragua. Finally, the I. p. espinachi subspecies is native to southwestern Nicaragua and northwestern Costa Rica. Spot-breasted orioles have been introduced to the United States in southeast Florida. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

Habitat

Spot-breasted orioles prefer to nest and breed in areas of sparse arid woodlands, with a native population of mimosa (Mimosa spp.), acacia (Acacia spp.) and mesquite (Prosopis spp.). Orioles are also known to frequent agriculturally developed areas such as coffee plantations, villages and pastures, generally preferring to stay in areas with large amounts of shade. In Florida spot-breasted orioles inhabit urban areas from Palm Beach south to Miami, as long as there is enough shade and flowering trees. All subspecies present in Mexico tend to stay in the lowlands. However, they can be found in higher altitude areas further south into Guatemala. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

  • Range elevation
    0 to 1500 m
    0.00 to 4921.26 ft

Physical Description

Spot-breasted orioles have bright orange reddish hue covering the entirety of their rumps, breasts, sides, vent, and also up towards the head covering the crown and nape. They have black coloration on their tails, wings, and throat, with white patches on the wings. Their major defining feature is the black spots present on the breast. They do not exhibit sexual dimorphism, as females are only a slightly duller color with a possible olive brownish hue to the underside of the tail. Elaborate coloration in both sexes is common in tropical orioles. (Hofmann, et al., 2008; Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    48.7 g
    1.72 oz
  • Average length
    12 cm
    4.72 in

Reproduction

All orioles are thought to be socially monogamous. (Hofmann, et al., 2008; Jaramillo and Burke, 1999)

Spot-breasted Orioles are territorial with very distinctive nesting behavior and structure. It constructs distinctive hanging nests made of dried grasses or thin roots and are about 20 inches long and 5 inches wide at the base (typical of many closely related orioles). These nests are known to hang in tall trees, spiny trees host to aggressive stinging ants, or even suspended from power lines. Nests have also been known to be parasitized by the bronzed cowbird. One very unusual behavior documented in Guatemala was the raising of two broods at once; the male would take care of the first brood, while the female would begin incubation on the second. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

  • Breeding interval
    Spot-breasted orioles generally breed once per season, but may breed twice per season in Florida.
  • Breeding season
    Spot-breasted orioles made between April and July.
  • Average eggs per season
    3

Females exclusively incubate the eggs, while chicks are fed by both parents. Little is known about incubation and nesting periods. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

Lifespan/Longevity

Little or no published information.

Behavior

While foraging, spot-breasted orioles are known to travel in pairs and small groups. They forage insects by rummaging through dead leaves and gleaning from green leaves. Spot-breasted orioles also known to snip bits of flowers (mainly Hibiscus) off using their beak in order to get to the nectar. Both sexes are prominent singers, with the males perching on bare branches or power lines in order to project. Orioles are very apt at adjusting to urban environments, shown in both the US and its native range. Females are the primary nest builders, while males take an important parental role once the chicks are hatched. Spot-breasted orioles live sympatrically with other oriole species, mainly altimira and streak-backed orioles, and spot-breasted oriole are the least common. It is striking that these three species have such similar appearance even though they are not very closely related (Omland and Lanyon, 2000). (Jaramillo and Burke, 1999; Omland and Lanyon, 2000; del Hoyo, et al., 2011)

Home Range

Spot-breasted orioles are likely territorial, perhaps year round as are many tropical birds (Hofmann et al. 2008). However, the size of their home range is unknown. (Hofmann, et al., 2008)

Communication and Perception

As in many tropical birds, both males and females sing (Price, Lanyon and Omland, 2009). Spot-breasted orioles sing year long, at least where it has been observed, in Florida. Their song is described as a repetitive warbled set of whistled with lengthy structure and a very appealing tone (similar to that of altamira orioles). Notes used for each song are distinct for that particular instance, changing in tone, frequency, timbre and length each time they sing. (Jaramillo and Burke, 1999; Price, et al., 2009; del Hoyo, et al., 2011)

Food Habits

Spot-breasted orioles primarily prey on insects and other arthropods, as well as fruits and nectar, including nectar of the trees in the genera Carpodacus, Caesalpinia, and Gliricidia. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

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

Predation

Nests can be parasitized by bronzed cowbirds and have been shown to host fledglings of giant cowbirds in populations in Nicaragua. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

Ecosystem Roles

Little is known about the role spot-breasted orioles play in their ecosystem. However it likely pollinates flowers from which it gets nectar, disperses seeds of berries and other fruits, and impacts populations of insects and other prey. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

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

Economic Importance for Humans: Positive

There are no known positive economic impacts of spot-breasted orioles on humans.

Economic Importance for Humans: Negative

There are no known negative economic impacts of spot-breasted orioles on humans.

Conservation Status

Spot-breasted orioles are either common or uncommon throughout their entire geographic range. They are very accepting of man-made nesting habitats and after accidental introduction into Florida, they are relatively common in Brevard and Dade Counties. (Jaramillo and Burke, 1999; del Hoyo, et al., 2011)

Other Comments

Based on a 2010 study by Jacobsen, Friedman, and Omland with data from mitochondrial and nuclear DNA, spot-breasted orioles were most closely related to white-edged orioles in a group of tropical orioles known as Clade B. (Jacobsen, et al., 2010)

Contributors

Ian Realo (author), University of Maryland, Baltimore County, Kevin Omland (editor), University of Maryland, Baltimore County, Laura Podzikowski (editor), Special Projects.

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.

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

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

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

female parental care

parental care is carried out by females

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.

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).

male parental care

parental care is carried out by males

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

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.

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

social

associates with others of its species; forms social groups.

suburban

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

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

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

visual

uses sight to communicate

References

Hofmann, C., T. Cronin, K. Omland. 2008. Evolution of sexual dichromatism 1. Convergent losses of elaborate female coloration in New World orioles (Icterus spp.). Auk, 125: 778-789.

Jacobsen, F., N. Friedman, K. Omland. 2010. Congruence between nuclear and mitochondrial DNA: Combination of multiple nuclear introns resolves a well-supported phylogeny of New World orioles. Molecular Phylogenetics and Evolution, 56: 419-427.

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

Omland, K., S. Lanyon. 2000. Reconstructing plumage evolution in orioles (Icterus): repeated convergence and reversal in patterns. Evolution, 54: 2119-2133.

Price, J., S. Lanyon, K. Omland. 2009. Losses of female song with changes from tropical to temperate breeding in the New World blackbirds. Proceedings of the Royal Society of London, B. Biological Sciences, 276: 1971-1980.

del Hoyo, J., A. Elliott, D. Christie. 2011. Handbook of Birds of the World. Barcelona, Spain: Lynx Edicions.

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