Bullock's oriole (Icterus bullockii) is a small New World blackbird. At one time, this species and the Baltimore oriole were considered to be a single species, the Northern oriole. This bird is named after William Bullock, an English amateur naturalist.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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InsectivoresAn insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which also refers to the human practice of e...
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HerbivoreA herbivore is an animal anatomically and physiologically adapted to eating plant material, for example, foliage, for the main component of its die...
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FrugivoreA frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts, and seeds. Approx...
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NectarivoreIn zoology, a nectarivore is an animal that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of the sugar-...
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ArborealArboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
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ZoochoryZoochory animals are those that can disperse plant seeds in several ways. Seeds can be transported on the outside of vertebrate animals (mostly mam...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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TerritorialA territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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AltricialAltricial animals are those species whose newly hatched or born young are relatively immobile. They lack hair or down, are not able to obtain food ...
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Serial monogamySerial monogamy is a mating system in which a pair bonds only for one breeding season.
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FlockingFlocking birds are those that tend to gather to forage or travel collectively. Avian flocks are typically associated with migration. Flocking also ...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withAdult Bullock's orioles have a pointed bill with a straight culmen. In adult males, the tail is long, square, and jet black. All exposed skin is black, as are the claws and bill, though the base of the lower mandible lightens to bluish-gray. Adult males have a strongly contrasting orange and black plumage, a black throat patch, and a white wing bar. The underparts, breast, and face are orange or yellow; by contrast, the back, wings, and tail are black. A black line extends from each eye to the black crown. The wing coverts (feathers not directly used in flight) are fringed white, forming a wing patch. Although the tail is mostly black, the outermost three or four rectrices (flight feathers) are tipped orange, forming a "T" shape. Adult females, by contrast, have gray-brown upperparts, duller yellow on the breast and underparts, and an olive crown. Some females may also have a dark throat patch, similar to (but less extensive than) the one found in adult males; in all cases, females lack the black eye-line present in adult males. Females with throat patches are thought to be older individuals. Juveniles resemble adult females but have darker wings, fresh wing coverts, and a pink or whitish bill.
Bullock's orioles are found in western North America, though they sometimes occur as vagrants in the eastern half of the continent. During the breeding season, they are found as far west as the eastern foothills of the Cascade Range. Their breeding range stretches east to the Dakotas, Kansas, and northern Central Texas. These birds can be found as far north as British Columbia in Canada and as far south as Sonora or Durango in Mexico. During winter, they retreat to Mexico and northern Central America and their winter range extends south and east from Sinaloa to Oaxaca. Bullock's orioles prefer habitat edges. They especially prefer riparian corridors, open deciduous woodland, and scrub forest. During the breeding season, they prefer areas with an abundance of cottonwood, pecan, and (if near water) willow. In dry areas, Bullock's orioles favor salt cedar and mesquite.
Bullock's orioles are social but during the breeding season they usually spend time in pairs and only sometimes can form small groups. These birds are active during the day. They forage in trees and shrubs, also making short flights to catch insects. Bullock's orioles also readily come to a dish filled with grape jelly. Their parents lead the fledglings, feed them jelly, and then the adult males leave the area. The young stay at the jelly dish from first feeding in early July and leave in late September. Both male and female Bullock's orioles sing. While males have a sweeter voice, females tend to be more prolific singers. Their song is similar to that of the Baltimore oriole but faster and somewhat more harsh. When it's time to migrate, Bullock's orioles usually fly at night in small flocks.
Bullock's orioles are carnivores (insectivores) and herbivores (frugivores, nectarivores). They mainly eat insects, berries, and nectar. Other fruits eaten include oranges and sometimes grapes. In some locations, they may be seen using hummingbird feeders.
Bullock's orioles are serially monogamous meaning they form pairs only for one breeding season. They usually breed from May until July. The exact timing of the beginning of the breeding season tends to vary geographically; in general, breeding begins later in the northernmost and westernmost portions of its geographic range. Despite being territorial during the breeding season, mated pairs cooperate to weave deep, pendant baskets in which are deposited between 3 and 6 eggs, though females tend to do much of the work. The nest is woven of plant fibers, primarily bark, and fine grass fiber, though animal hair is also commonly used. The nest is lined with down, hair, and moss. Only the female incubates the eggs during 12-14 days but both parents rear the young and defend the nest from predators and nest parasites. The chicks fledge in 2 weeks after hatching and usually stay in family groups.
Bullock's orioles are not threatened at present. However, the riparian habitat they live in is being lost due to irrigation, and Bullock's orioles may suffer from the use of pesticides through direct contamination and loss of insect prey.
According to the All About Birds resource the total breeding population size of the Bullock's oriole is 7.4 million individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
When feeding on various fruits and berries Bullock’s orioles act as seed dispersers. This way they help to spread the seeds throughout their natural habitat.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...