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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.
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
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.
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.
Altamira orioles also use their keen vision and hearing as their main modes of perception.
Communication Channels: visual ; acoustic
Other Communication Modes: duets
Perception Channels: visual ; tactile ; acoustic ; chemical
Altamira orioles are not considered threatened, although local populations may be negatively affected by habitat destruction.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
There are no known negative effects of Altamira orioles on humans.
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
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:
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.
Animal Foods: insects
Plant Foods: seeds, grains, and nuts; fruit; nectar
Primary Diet: carnivore (Insectivore )
Biogeographic Regions: nearctic (Native )
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; scrub forest
Wetlands: swamp
Other Habitat Features: riparian
There is no published longevity data available for Altamira orioles.
Average wingspan: 125 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger
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.
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
Mating System: monogamous
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.
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.
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.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
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.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Protecting: Male, Female)
