Icterus gularisAltamira oriole

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Geographic Range

Habitat

Physical Description

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • Average wingspan
    125 mm
    4.92 in

Reproduction

Altamira orioles are seasonally monogamous and may be for life. They are almost always seen in pairs. Breeding begins in the spring and continues through the summer (Jaramillo and Burke, 1999)

Altamira orioles start building their nests as early as March. Generally they only produce one brood per season. However, more southerly populations can produce a second brood. In the event that they brood a second time, a second nest is always built. Nests are hanging baskets, which can be up to 65 cm long, and are built entirely by the female. Nests are built in approximately 3 weeks. Often built at the tip of a yielding branch (usually Mimosa) or a power line; the nests are rarely hidden. Built at an average of 9.3 m from the ground, nests are inaccessible by non-avian predators. Altamira orioles seem to prefer the northwest quadrants of trees, as 9 out of 10 nests have been observed to be built there in a tree's canopy. (Brush, 2005; Jaramillo and Burke, 1999)

In Northern Mexico and Texas, breeding begins in April and lasts through July or August. In Oaxaca, Mexico, breeding starts a little later, in May, and goes through July. The average clutch size is 4.9, but decreases as one moves south. The average incubation period is 14 days. Little is known of the time to fledging. However, the offspring and adults become hostile, chasing away other species of birds for approximately one week after the young leave the nest. (Brush, 2005; Jaramillo and Burke, 1999)

  • Breeding interval
    Altamira orioles breed once or twice a year.
  • Breeding season
    Breeding occurs from April to August.
  • Average eggs per season
    4.9
  • Average time to hatching
    14 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Young are fed by both males and females about every six to eight minutes during the day. In the event that a pair broods a second time, males will assume most of the feeding responsibility, while females build a second nest. Usually, fecal sacs are removed only by females. (Brush, 2005)

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

Lifespan/Longevity

There is no published longevity data available for Altamira orioles.

Behavior

Altamira orioles are usually seen in pairs. They rarely have intraspecific conflicts. Nests are solitary, and are not colonial. However, feeding flocks may be formed in the winter. Altamira orioles fly in jerky and swift movements from perch to perch. Altamira orioles are never seen perching or walking on the ground. (Brush, 2005; Jaramillo and Burke, 1999)

Home Range

At the Santa Ana Wildlife Refuge, the average distance between nesting sites was 250 m, and individuals were observed to fly 400 m daily, to search for food. (Brush, 2005)

Communication and Perception

Their singing is described as being "a loud, musical, but hesitant series of whistles, reminiscent of an inexperienced human whistler." Raspy, harsh notes may be used as an alarm call, while a quick, nasal "ike" may be used as a contact call between adults and upon arrival at the nest. (Brush, 2005)

Nestlings have a relatively quiet, low pitched begging call. Interestingly, some nestlings in northern Texas apparently produce no sound, perhaps to avoid predation. Males will sometimes develop adult song before they have fully developed plumage. (Brush, 2005)

Altamira orioles also use their keen vision and hearing as their main modes of perception.

  • Other Communication Modes
  • duets

Food Habits

Altamira orioles are predominantly insectivores. However, they will occasionally eat fruit and nectar. It is postulated that they may eat seeds and nuts at some point in the year, due to the formidable size and structure of their bill. Nestlings are mainly fed orthopterans and insect larvae. (Brush, 2005; Jaramillo and Burke, 1999)

  • Animal Foods
  • insects
  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • nectar

Predation

Altamira orioles have no known predators. Although it is possible that adults are taken by diurnal raptors and that eggs and nestlings might be taken by arboreal predators such as snakes and Bassariscus species. (Brush, 2005; Jaramillo and Burke, 1999)

Ecosystem Roles

As they are occasionally frugivorous, Altamira orioles aid in the dispersal of seeds. They are also important as predators of insects. While bronzed cowbirds (Molothrus aeneus) have been observed attempting to parasitize nests, they are almost never successful.

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species

Economic Importance for Humans: Positive

An attractive bird, Altamira orioles are popular among bird enthusiasts, potentially acting to draw ecotourism to areas they inhabit. As any member of a community within an ecosystem, they are integral to the function of the ecosystem, contributing to its health and beauty.

  • Positive Impacts
  • ecotourism
  • research and education

Economic Importance for Humans: Negative

There are no known negative effects of Altamira orioles on humans.

Conservation Status

Altamira orioles are not considered threatened, although local populations may be negatively affected by habitat destruction.

Other Comments

Altamira orioles have been integral to some stimulating research concerning the evolution of plumage in the genus Icterus. Dr. Kevin Omland has found several instances of convergent evolution in a variety of plumage characters within the genus, which can be summarized into two plumage types: Altamira plumage type and Baltimore plumage type. Omland and collegues have found that, while Baltimore orioles Icterus galbula, and Altamira orioles have very different plumage, their DNA characteristics demonstrate that they are quite closely related. Furthermore, plumage characteristics that are strikingly similar to that of Altamira orioles can be found in more distantly related species, such as spot-breasted orioles, Icterus pectoralis. (Omland and Lanyon, 2000)

There is a consistent trend within the genus Icterus for males and females of tropical, non-migratory species to share plumage configurations. However, males of most temperate, migratory species have bright plumage characters and females have dull characters. In addition to his other work, Dr. Omland and his graduate students are trying to understand the function of bright female plumage in these and other tropical orioles. For more details on this research, visit the Omland Lab website at: http://www.umbc.edu/biosci/Faculty/OmlandLabWebpage/NewPages/index.htm (Omland and Lanyon, 2000)

Contributors

Ryan Ihnacik (author), University of Maryland, Baltimore County, Kevin Omland (editor, instructor), University of Maryland, Baltimore County.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

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.

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.

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

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

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

Brush, T. 2005. "The Birds of North America Online" (On-line). Accessed March 15, 2005 at http://bna.birds.cornell.edu/BNA/account/Altamira_Oriole/.

Jaramillo, A., P. Burke. 1999. New World Blackbirds: The Icterids. 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.