Download Passerina cyanea indigo bunting

Passerina cyanea
indigo bunting
By Rishauna Zumberg
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Aves
Order: Passeriformes
Family: Cardinalidae
Genus: Passerina
Species: Passerina cyanea
Washtenaw County Audubon Society (copyright holder)
Geographic Range
Indigo buntings (Passerina cyanea) breed throughout eastern North America from the
Great Plains eastward, south of the coniferous forest region. There are also some
breeding populations in the western United States, including Utah, Arizona and
California. Indigo buntings winter in the coastal regions of Mexico, Central America,
northern South America and the Caribbean.
Habitat
Indigo buntings breed in brushy and weedy habitats along the edges of farmed land,
woods, road, power lines, railways and riparian habitats. They also breed in clearings in
open deciduous woodlands, in weedy or abandoned agricultural fields, and in swamps.
During migration they look for open grasslands and leafy trees similar to those in their
winter habitat. In winter, indigo buntings choose open habitats, such as weedy fields,
citrus orchards, savannas, weedy croplands and low second growth (Payne 1992).
Physical Description
Mass
12 to 18 g; avg. 15 g
(0.42 to 0.63 oz; avg. 0.53 oz)
Length
11.50 to 13 cm
(4.53 to 5.12 in)
Adult male indigo buntings are brilliant blue during the breeding season, with a darker
almost purple crown. Females and young are brown with buff wingbars and only a tinge
of blue on their tail and shoulders. Indigo buntings are small birds, from 11.5 cm to13
cm long and weighing 12 to 18 g. They have short, conical beaks and black or gray legs
and feet. (Payne 1992, Robbins, Bruun and Zim 1983)
Reproduction
Breeding interval
Indigo buntings breed between May and September, with most activity occurring June
through August.
Breeding season
Indigo buntings may raise more than one brood per season, and may switch nests or
mates between broods.
Eggs per season
1 to 4; avg. 3.50
Time to hatching
11 to 14 days; avg. 12.50 days
Time to fledging
8 to 14 days
Time to independence
3 weeks (average)
Age at sexual or reproductive maturity (female)
1 years (low)
Age at sexual or reproductive maturity (male)
1 years (low)
Indigo buntings are socially monogamous. However, pairs only associate until
incubation begins, and may switch partners within a single breeding season.
Fertilizations outside of a breeding pair are not uncommon and approximately 15% of
males have more than one mate.
Males do not sing often in courtship, but they do follow their mate around during the
nest building and laying periods, often chasing other males away.
Indigo buntings breed between May and September, with most activity occurring June
through August. They may raise more than one brood per season, and may switch nests
or mates between broods. The female chooses the nest site and builds the nest, which
may take up to eight days. Nests are built in shrubs in fields or at the edges of woods,
roadsides and railways. They are constructed of leaves, grasses, stems and strips of
bark. After the nest is complete, the female lays 1 to 4 (usually 3 or 4) white eggs. One
egg is laid each day, soon after sunrise. The female begins incubating after the last egg
is laid. Incubation lasts for 11 to 14 (usually 12 to 13) days.
The female broods the altricial chicks for the first few days after they hatch. She also
feeds the chicks insects and removes their fecal sacs from the nest. The chicks leave the
nest 8 to 14 days after hatching, and become independent about 3 weeks after fledging.
Indigo buntings are sexually mature at one year old.
The male does not generally help with incubation or raising the chicks. The female
chooses the nest site and builds the nest. She broods the altricial chicks for the first few
days after they hatch, feeds them insects and removes their fecal sacs from the nest. The
chicks leave the nest 8 to 14 days after hatching, and become independent about 3
weeks after fledging.
Lifespan/Longevity
Extreme lifespan (wild)
10 years (high)
Average lifespan (wild)
111 months
[External Source: Bird Banding Laboratory]
Indigo buntings can live up to 10 years in the wild.
Behavior
Territory Size
0.00 to 0.08 km^2
Indigo buntings are generally solitary. During the breeding season, males establish and
defend a territory 0.4 to 8 ha in size. Each territory may hold one or more females.
During the winter, indigo buntings roost in a flock at night, but spend the days foraging
alone or in small groups. There appears to be no dominance hierarchy within these
groups. (Payne 1992)
Indigo buntings are migratory, and may fly as far as 2000 miles between their wintering
and breeding grounds. They leave their breeding grounds in September and October,
and leave their wintering grounds to return in late April and May. They migrate largely
at night. (Payne 1992, Robbins, Bruun, and Zim 1983, Scientific American 1980)
Home Range
In one study, 10% of banded fledglings returned to breed within 1 to 2 km of their natal
site (Payne 1992).
Communication and Perception
Indigo buntings use vocalizations and visual cues to communicate. Only male indigo
buntings sing. Each male has one complex song that it sings, during the breeding season
to advertise occupancy of a territory to other males and to attract females. Males may
also court females by performing displays, such as the display in which a male struts in
circles in front of a female with his wings spread and his head crouched.
Food Habits
During the breeding season, indigo buntings eat small spiders and insects, seeds of
grasses and herbs, and berries. Major food items taken include caterpillars,
grasshoppers, bugs, beetles, seeds and berries. In winter, indigo buntings eat small
seeds, buds, and some insects. Their main food in winter is small seeds of grasses. They
also frequent feeders, and eat the seeds of rice in rice fields. Indigo buntings do not
appear to drink frequently, and may obtain sufficient water from their diet. (Payne
1992)
Indigo buntings feed alone during the breeding season and in flocks during the winter.
They do not appear to store food for later consumption. (Payne 1992)
Animal Foods:
insects; terrestrial non-insect arthropods.
Plant Foods:
seeds, grains, and nuts; fruit.
Predation
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Known predators
Virginia opossums (Didelphis virginiana)
red foxes (Vulpes vulpes)
feral cats (Felis silvestris)
blue jays (Cyanocitta cristata)
blue racers (Coluber constrictor)
raccoons (Procyon lotor)
Although predation of adult indigo buntings surely occurs, specific predators have not
been identified. Brooding females, eggs and young are vulnerable to predation from
climbing predators, including raccoons, opossum, red fox, feral cats, blue jays and blue
racers.
When a predator approaches a nest, adult buntings may feign injury and make a chipchip-chip call to distract the predator and lure them away from the nest. They do not
mob predators.
Ecosystem Roles
Perching birds (order Passeriformes) as a group play an important role in the earth's
ecosystems. They consume many varieties and amounts of food and serve as food for
others and hosts for parasites (Britannica, 1986). Indigo buntings affect the populations
of the insects they eat, and help distribute seeds of the plants whose berries they eat.
They also host at least one parasite; hippoboscid flies (Payne 1992).
Key ways these animals impact their ecosystem:
disperses seeds.
Economic Importance for Humans: Negative
There are no known adverse affects of indigo buntings on humans.
Economic Importance for Humans: Positive
There is apparent aesthetic importance of songbirds like the Indigo bunting to bird
watchers and listeners. This brightly colored species is commonly kept as a cage bird
(Britannica, 1986).
Conservation Status
IUCN Red List:
Least Concern.
US Migratory Bird Act:
Protected.
US Federal List:
No special status.
CITES:
No special status.
Indigo buntings appear to be increasing in geographic range and density. They are
protected under the U.S. Migratory Bird Act, but not under CITES or the U.S.
Endangered Species Act.
Indigo buntings are occasionally killed for sport and food. They are also a popular cage
bird in Europe and Mexico. (Payne, 1992)
Contributors
Rishauna Zumberg (author), University of Michigan.
References
Payne, R. 1992 The Birds of North America, No.4, Indigo Bunting. A. Poole, P.
Stettenheim, and F. Gill, Editors.
Robbins, Bruun, and Zim 1983, A Guide to Field Identification, Birds of North
America. Golden Press.
Scientific American. 1980, Birds, W.H. Freeman and Company, San Francisco; p.68.
The New Encyclopedia Britannica, Vol.15. !986, Birds, Encyclopedia Britannica, Inc.
Chicago; p. 95-96.