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Icterus parisorumScott's oriole

By Tracy Forrester

Geographic Range

The Scott's Oriole is almost completely confined to the Lower and Upper Sonoran Zones. This oriole breeds in the Lower Sonoran Zone from southern California, Nevada, Utah, western Colorado, central New Mexico and western Texas and south into Mexico, to Nuevo Leon, Vera Cruz, Puebla, and Lower California. Of these, Vera Cruz seems to be the least rich in Scott's Orioles, most likely due to its humid mountains. This bird's range is not changing at this point , however, with increasing climate change, the range will most likely move.

It winters in northwestern Mexico from Lower California, Sonora and Chihuahua, along the coast south to Oaxaca and in southern California. It is present year-round in the central and southern regions of Mexico. It is casually found throughout the western portion of the United States and also in Minnesota, Wisconsin, and Louisiana. (Bailey, 1928; Brandt, 1951; Ligon, 1961; Loetscher, 1955)

Habitat

Scott's Orioles often live in yucca gardens on desert grassland prairies, but they have been found wherever yucca is growing, even on the hillsides of mountain canyons. It primarily uses Torrey and soaptree yuccas. Occasionally, these orioles have been found to live in other small, or large, trees. When they are in trees other than yuccas, they often feed and sing in pines, oaks, and riparian areas within pine-oak areas. In the summer, though, they most often live in live oak, Joshua trees and yucca. They always live within range of a reliable water source. They often shun the humid, forested mountains and the high plains areas. The Scott's Oriole, however, has been found in the lowest and hottest parts of New Mexico. They are most common on and near the desert foothills and mountains of southern and southwestern New Mexico. These birds prefer south-facing slopes. (Bailey, 1928; Brandt, 1951; Kozma et. al, 1997; Ligon, 1961; Marshall, 1957; Phillips, 1964)

Physical Description

The length of male Scott's Oriole is about 18.48-20.4 cm while its wings are 9.36-10.08 cm long. Its tail is 7.92-9.36 cm long. It has a sharp, pointed, dark bill that has a length of 2.16-2.4 cm. The feet of this bird are fitted only for perching. Adult males, in the spring and summer, have a black head and breast. Portions of the back, wings and tail are also black in color. Their scapulars, posterior parts of their backs, their bellies, rumps, shoulder patch, basal part of the tail, and upper and under tail and wing coverts are a bright lemon-yellow. There is no orange present on the Scott's Oriole, unlike other orioles. A white wing bar is also present. Males' bills are black with an upper base that is bluish gray. Adult males in the winter look similar to how they do in the summer, except that the white markings on the wings are broader, the feathers of the back are edged with gray, the rump and upper tail coverts are washed with olive or gray and their flanks are tinged with an olive color. Immature males have similar characteristics with females, however, the immature male's head is mostly black by its first spring, while the female's is only black when it is very old. It takes two years for a juvenile to reach full plumage.

Females are, on average, smaller than the males. Adult females have olive-gray under parts and top of the head with dark streaks on the back. There is no brown present on the body. The body color becomes yellowish on the rump and upper tail coverts. They also have two wing bars, as opposed to the male's one wing bar. The female's throat is sometimes spotted, clouded, or washed with black. Old females usually have a completely black throat. Immature females are duller in color, without a trace of black. (Bailey, 1928; Brandt, 1951; Ligon, 1961; Phillips, 1964)

Reproduction

The Scott's Oriole breeds in spring and summer. The eggs are laid in nests located in shrubs and in the canopies of trees at the branch base. The height of the nesting season is in late May or early June. It is a monogamous species that is with its mate for one breeding season. Its eggs have an incubation period of 7-14 days. The nestling period is 14 days. The average number of offspring per reproductive effort is 3-4 chicks. Both parents take care of the young. Males demand a large territory in order to attract a mate and will defend it well. It is possible that the Scott's Oriole could be subject to cowbird parasitism because cowbirds are present within the orioles' range. If parasitism is occurring, however, it does not appear to have an effect on population sizes.

The Scott's Oriole weaves a pendant nest made out of the tough fibers of the dried leaves of the yucca and palm fibers. The color of these dried leaves acts as camouflage for the nest. It hangs its nest high up in the yucca, amongst the long, green leaves. It is usually placed in the dead portion of the yucca, underneath the live crown, where it is laced to the dead blades. This provides protection from bad weather and any enemies that may come along.

At times, the Scott's Oriole will construct its nest with grasses and hang it from other trees, including junipers and scrub pinion. Occasionally the nests are hidden in clumps of mistletoe and lined with a few horse hairs. The nest of the Scott's Oriole is so well constructed that it often remains intact for several years.

The eggs of the Scott's Oriole are bluish in tint and the largest of the orioles in the southwestern United States. There are usually 3 or 4 that are blotched, streaked and spotted with black, gray, or brown and purple, typically around the larger end of the egg. (Bailey, 1928; Brandt, 1951; Ligon, 1961; Marshall, 1957)

  • Average eggs per season
    3
    AnAge
  • Average time to hatching
    14 days
    AnAge

Lifespan/Longevity

Behavior

This oriole has a cautious temperament. It rarely comes out of wooded areas, unless to defend its territory from a would-be intruder, like a Mexican Jay or a Blue Jay. It hides its nest so deeply within a yucca, it is considered to be one of the most secure birds in North America. In the spring migration, adult males show up first, followed by the females, and finally the juvenile males.

The song of the Scott's Oriole sounds a lot like that of a Western Meadowlark, except it is more repetitious, has more volume and it can be heard at a greater distance.

(Bailey, 1928; Brandt, 1951; Ligon, 1961).

Communication and Perception

Food Habits

The Scott's Oriole mainly eats insects, such as grasshoppers, small beetles, caterpillars, butterflies and insect larvae. It also eats berries and cactus fruit. It will also sometimes probe flowers for nectar. This bird obtains gleans insects that are attracted to the flowers of yuccas. The ants, bees and other insects that are attracted to this plant's flower provide an ample food source.

They also utilize the century plants' and lechuguillas' as a food source for the nectar and insects attracted to these blossoms. Flowers of the agave also provide insects for this Oriole to feast upon.

When away from their nests and getting food, Scott's Orioles do not appear to be aggressive to other birds that are also attempting to feed. (Bailey, 1928; Brandt, 1951; Del Rio, 1987).

Economic Importance for Humans: Positive

This bird is an important natural control of insects. Scott's Orioles are vitally important to the yucca because they keep the number of pronumba moths low. These moths use the seeds of the yucca as food for their larvae. When the moths are fluttering about the yucca, the Scott's Oriole can have a quick and easy meal.

The Scott's Oriole also serves as an attraction to birders around the world. Birding tourists bring money into the southwest United States and Mexico, thereby supplementing the economy of both areas. (Brandt, 1951).

Economic Importance for Humans: Negative

There does not appear to be any negative economic consequences to the Scott's Oriole. It does not decimate yucca populations nor does eat anything of economic value to the human population.

Conservation Status

The Scott's Oriole is not listed on any of the IUCN's species list. This bird appears to be quite numerous. Scott's Orioles are extremely dependent upon yucca for their nests, food and protection. It is quite obvious that the Scott's Oriole shares a mutualism with the yucca plant. The yucca is very important to the life of the Scott's Oriole. Decimation of yucca populations by cattle grazing has been and is detrimental to this species. Southwestern desert areas where yuccas are found must be protected from destruction in order to keep Scott's Orioles' populations healthy.

On top of this, many of the best yucca plants that are left are located by the side of roads. This is very dangerous for these birds because they often are hit by automobiles when attempting to leave their nest, cross the road, and find food or a mate.

Agaves are also important to the Scott's Oriole, for many of the same reasons that yuccas are important. They also provide food and shelter for Scott's Orioles and so they too must be protected.

Populations of Neotropical bird migrants have declined recently, most likely due to the destruction of breeding and wintering habitat. This, too, could happen to the Scott's Oriole if habitat destruction continues in southwestern United States and Mexico. (Bailey, 1928; Brandt, 1951; Kozma et al, 1997)

Contributors

Tracy Forrester (author), University of Michigan-Ann Arbor, Terry Root (editor), University of Michigan-Ann Arbor.

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

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

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.

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

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

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.

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).

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.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

visual

uses sight to communicate

References

Bailey, F. 1928. Birds of New Mexico. Washington, D.C.: Judd & Detweiler, Inc..

Brandt, H. 1951. Arizona and Its Bird Life. Cleveland: The Bird Research Foundation.

Del Rio, C., L. Eguiarte. 1987. Bird visitation to Agave salmiana: comparisons among hummingbirds and perching birds.. Condor, 89: 357-363.

Kozma, J., N. Mathews. 1997. Breeding bird communities and nest plant selection in Chihuahuan Desert habitats in south-central New Mexico.. Wilson Bulletin, 109: 424-436.

Ligon, J. 1961. New Mexico Birds and Where to Find Them. Albuquerque: The University of New Mexico Printing Plant.

Loetscher, F. 1955. North American migrants in the state of Veracruz, Mexico: a summary.. Auk, 72: 14-54.

Marshall, J. 1957. Birds of Pine-Oak Woodland in Southern Arizona and Adjacent Mexico. Berkeley: Cooper Ornithological Society.

Phillips, A., J. Marshall, G. Monson. 1964. The Birds of Arizona. Tucson: The University of Arizona Press.

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