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Volatinia jacarinablue-black grassquit

By Eun-Young Seo

Geographic Range

Volatinia jacarina occur from Mexico and Central America southward through Brazil to Chile and Argentina. They are abundant resident of fields, grassland and clearings everywhere between elevations of about 5000 to 8000 feet from sea level. (De Schauensee, 1966; Dickey and Rossem, 1938; Dunning and Ridgely, 1987)

Habitat

Volatinia jacarina inhabit forest edges, woodland, wet grassland, and cultivated area. They are also found around tangles of weeds and vines, cropped pastures, sugar cane, lava flows, tule marshes, mimosa thickets, pine woods, and even in the cloud forest. The greatest concentrations occur in open country grown extensively with bunch grass and mimosa brush. (Davis, 1972; Ministry of Natural Resources' Land Information Centre, 01.19.1998)

Physical Description

Volatinia jacarina are on average 10 cm in length (wing = 53 mm, tail = 44 mm, and bill = 10 mm). The male are distinguished from the brownish females and juveniles by their glossy black plumage and white underwings. The male has a concealed white spot at the juncture of the wing and body that can be seen in display flights. Females have greyish brown upperparts and pale beige below. Their throat and breast are steaked greyish brown. The iris is dark brown. The upper mandible is black, while the lower mandible is bluish grey. Feet are grey (Davis 1972; Dubs 1999).

A juvenile male has a complete postjuvenal molt in the very late fall or early winter which results in a plumage very similar to the adult female, except that the wings and tail are dull black with olive or brownish edgings. In the following early summer, there is a prenuptial body molt which produces a glossy, blue-black plumage like the adult summer male. The body molt occurs during May and June. The female also have two body molts a year, molting in the early summer to a plumage decidedly less brownish than the winter dress. As in the male, the complete molt starts as early as the last week in April (Davis 1972). (Davis, 1972; Dubs, 1992)

  • Sexual Dimorphism
  • male more colorful
  • Average length
    10 cm
    3.94 in

Reproduction

Courting begins in early May and, since males can be seen performing until late in August, it is probable that the breeding season roughly corresponds to these dates. The height of the season is from early June to late August. The nests are constructed during July and they are made with marsh grass and plant fibers among the tufts of grasses or in low shrubs. The nest looks like an wiry basket and are remarkably rigid even though the bottoms and sides can be seen through. The female normally lays two or three eggs that are greenish or bluish white with dark spots. (Dickey and Rossem, 1938)

Behavior

Volatinia jacarina is usually found in groups all year around (Dickey and Rossem 1938).

This species are said to be nonmigratory. However they are observed seasonally in the Pocone region of Brazil from January to May (Dubs 1992).

The concealed white shoulder patches of the males play a prominent part in the courtship display, which begins as soon as the immense flocks of the winter and spring commence break up into pairs in early May. At the conclusion of the short, high-pitched, insect-like buzz which constitutes the song, the males pop up in an explosive leap which carries them two feet or more straight into the air. As they descend head first, the snowy shoulder patches are thrown out and are very conspicuous, even from a distance. This performance is repeated every few seconds (Davis 1972). (Davis, 1972; Dickey and Rossem, 1938; Dubs, 1992)

Communication and Perception

Food Habits

They are basically small seed-eaters, but they also often feed on small insects. The type of seeds eaten depend on what plant species are available. (Dubs, 1992)

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

Economic Importance for Humans: Positive

Volatinia jacarina are enjoyed by birdwatchers. They are relatively easy to be seen so they are tourist attractions in many Central and South American countries.

This species are also prefered as a backyard bird with other finches. They are sometimes raised in large aviaries (Garrigues 1999). (Garrigues, Feb, 1999)

Economic Importance for Humans: Negative

Volatinia jacarina are small seed eaters, so they are usually found near cultivated areas. They can cause crop losses for farmers. (Dickey and Rossem, 1938)

Conservation Status

Volatinia jacarina have no special conservation status as they are a common and widespread species.

Other Comments

It has been thought by Davis Steadman that the ancestral finch of the Galapagos might be V. jacarina. Some 100,000 years ago, grassquits probably made their way across the 600 miles of Pacific to Galapagos. The small birds happened upon a landscape relatively free of competitors, since the isolated location of the Galapagos meant that new species came there infrequently.

Contributors

Eun-Young Seo (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

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.

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.

chemical

uses smells or other chemicals to communicate

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

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).

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

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.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

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.

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

Davis, L. 1972. A Field Guide to the Birds of Mexico and Central America. Austin and London: University of Texas Press.

De Schauensee, R. 1966. The Species of Birds of South America. Narberth, Pennsylvania: Livingston Publishing Company.

Dickey, D., A. Rossem. 1938. Birds of El Salvador. Chicago, Illinois: Field Museum of Natural History.

Dubs, B. 1992. Birds of Southwestern Brazil. Pfaffikon, Switzerland: Schellenburg Druck AG.

Dunning, J., R. Ridgely. 1987. South American Birds. Pennsylvania: Harrowood Books.

Garrigues, R. Feb, 1999. "Birding the Americas Trip Report and Planning Repository" (On-line). Accessed 01/10/05 at http://maybank.tripod.com/SouthAmerica/Peru/Peru-02-99.htm.

Heinzelman, D. 1979. A manual for Bird Watching in the Americas. New York: Universe Books.

Kaufman, K. 2000. Birds of North America. New York: Houghton Mifflin Company.

Long, J. 1981. Introduced Birds of the World. New York: Universe Books.

Ministry of Natural Resources' Land Information Centre, 01.19.1998. "Belize Biodiversity Information System" (On-line). Accessed 3. 22. 01 at http://fwie.fw.vt.edu/wcs/045140.HTM.

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