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Carolina wren

Thryothorus ludovicianus

What do they look like?

Carolina wrens are small birds (though they larger than most wrens). They weigh about 20 g and are 12 to 14 cm long. Carolina wrens have a rusty-brown back and a lighter cinnamon-colored underside. Their throat and chin are white, and their wings and tail are brown with very fine black stripes. Carolina wrens also have a broad white stripe above each eye, which makes them easy to identify from other wrens. Carolina wrens have long, thin bills that curve downward. The top part of the bill (called the upper mandible) is dark, and the bottom part of the bill (called the lower mandible) is light-yellow. Carolina wrens have pink legs and long tails.

Male and female Carolina wrens are very similar. However, males are slightly heavier and often have longer bills, wings and tails. Young Carolina wrens look like adults, but are usually lighter colored. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965; Sauer, 1997; Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965; Sauer, 1997)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • sexes shaped differently
  • Average mass
    20 g
    0.70 oz
  • Average mass
    17.5 g
    0.62 oz
    AnAge
  • Range length
    12 to 14 cm
    4.72 to 5.51 in

Where do they live?

Carolina wrens are year-round residents of the southeastern United States. They are found from the Atlantic seashore to as far west as Texas, Nebraska, Kansas and eastern Oklahoma. They are found as far north as southern Michigan, New York, Massachusetts, and Ontario Canada. This species is also found in the northeast corner of Mexico and the Yucatan Peninsula, as well in a few spots in Central America. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995)

What kind of habitat do they need?

Carolina wrens can live in many different types of habitats. They prefer wooded areas that are moist rather than dry. They also need dense shrubs or brush for hiding and feeding. Some of the habitats where you might find Carolina wrens include wooded areas along streams and swamps, in thickets and shrubbery, in piles of logs or decaying wood, farmyards, forests, suburban gardens, live oak and palmetto hummocks, isolated clumps of trees in prairies, and old sheds. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965)

How do they reproduce?

Carolina wrens are monogamous. Males and females form breeding pairs that remain together for many years. Male Carolina wrens try to attract a mate by performing courtship displays for her. They may hop around the female in a circle while puffing out their feathers and fanning their tail. They may also bring food to a female to try to attract her. This is called courtship feeding. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965)

Carolina wrens breed between March and October. The male and female work together to build a nest. The nest is built in the mornings, and takes up to a week to build. Carolina wrens will build their nests in a wide variety of sites. These include upturned roots, tree stumps, vine tangles, conifer branches, overhangs, abandoned woodpecker holes, boxes, tin cans, old shoes, mailboxes, old articles of clothing and furniture, window sills and coffee pots. The nests are usually built of twigs, grasses, weeds, leaves, mosses, pine needles, bits of bark and found objects such as hair, string, feathers, etc. The average nest is 8 to 23 cm long and 8 to 15 cm wide. Nests are usually less than 1.8 m above the ground. Each nest is only used once.

Females lay 3 to 7 (average 4) eggs. One egg is laid each day in the early morning. The eggs are light cream to pinkish-white with dark spots near the ends. They are oval shaped and about 18 mm long. Females can begin laying eggs as early as March in southern populations and as early as April in northern populations. Carolina wrens nesting in the northern part of the range generally raise two broods per year, while pairs in the souther part of the range can raise up to three broods.

The female incubates the eggs for 12 to 16 days. Meanwhile, the male spends his time gathering food and delivering it to the female. When the chicks hatch, they are helpless. They have closed eyes (which open after three days), pale gray down, translucent pink skin and a yellow bill.

The female broods the chicks for the first four days after hatching. This protects them and keeps them warm. After four days, the female broods the chicks mostly at night. Both parents feed the chicks butterfly and moth larvae, crickets, grasshoppers and beetles.

The chicks leave the nest after 12 to 14 days. After they leave the nest, the chicks stay together and the parents continue to feed them for about 4 weeks. The young Carolina wrens are able to breed the next spring when they are about a year old. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965)

  • How often does reproduction occur?
    Carolina wrens may raise up to three broods per summer.
  • Breeding season
    Carolina wrens breed between March and October.
  • Range eggs per season
    3 to 7
  • Average eggs per season
    4
  • Average eggs per season
    5
    AnAge
  • Range time to hatching
    12 to 16 days
  • Range fledging age
    12 to 14 days
  • Average time to independence
    4 weeks
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Male and female Carolina wrens both care for their young. The male and female work together to build the nest and feed the chicks. The female incubates the eggs and broods the young herself. While she is doing this, the male brings food to her. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
  • pre-hatching/birth
    • provisioning
      • male
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

How long do they live?

The oldest known Carolina wren lived at least 6 years and 1 month. (Haggerty and Morton, 1995)

How do they behave?

Carolina wrens are diurnal (active during the day). They stay in the same area all year and do not migrate. They use calls and songs to defend a territory year-round.

Carolina wrens are mostly terrestrial. They spend most of their time on the ground, hopping around. They are able to fly, but usually do not fly very far. Instead, they use their wings to help them hop over tall objects.

Carolina wrens preen by using their bills and wings. They also dust-bath as a part of preening. (Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965)

  • Range territory size
    0.01 to 0.081 km^2

Home Range

One study in Alabama estimated the average home range of Carolina wrens to be 0.007 square kilometers. (Haggerty and Morton, 1995)

How do they communicate with each other?

Carolina wrens communicate using body signals and calls and songs. For example, Carolina wrens may use body signals to threaten another wren that enters their territory. To do this, a Carolina wren will hold their wings out, fan their tail and point their bill at the intruder.

Carolina wrens' songs are loud and high pitched. They sound like TEA-kettle, TWEEdle, SWEETheart, CHE-wortle, or CHOO-wee. Females are able to make sounds, but only males are able to make songs. The sounds and songs are used in many different situations. For examples, Carolina wrens may call or sing when they threaten a predator or another wren, while defending their territory, or to signal distress. Carolina wrens sing and call year-round. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965; Sauer, 1997)

What do they eat?

Carolina wrens are insectivores. They eat many different insects and spiders. They feed mostly on the ground, and seem to eat whatever they insects and spiders they find. Carolina wrens search for food by using their bills to move brush and vegetation, to search under brush piles, in decaying logs and trees, under tree bark, and around the banks of swamps. As ground feeders, Carolina wrens have trouble surviving long winters with a lot of snow. During harsh winters, Carolina wrens depend on bird feeders for food.

Scientists found that 94% of the food that Carolina wrens eat comes from animals (mostly insects) and 6% comes from plants (mostly seeds and fruit). Caterpillars and moths, bugs, beetles, grasshoppers, crickets, cockroaches, spiders, ants, bees, and wasps were the most common animal foods that Carolina wrens ate. Bayberry seeds, sweet gum, poison ivy, sumac, acorns and weeds were some of the plant foods that Carolina wrens ate. (Cornell Lab of Ornithology, 1999; Haggerty and Morton, 1995; Hill Collins, Jr. and Boyajian, 1965)

  • Animal Foods
  • amphibians
  • reptiles
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

What eats them and how do they avoid being eaten?

Birds such as blue jays, Cooper's hawks and sharp-shinned hawks are the most likely predators of adult Carolina wrens.

Carolina wren eggs and nestlings are eaten by raccoons, black rat snakes, gray squirrels, mink, gray foxes and eastern chipmunks.

When predators come near, Carolina wrens may call in alarm or chase after the predator, sometimes pecking at it. (Haggerty and Morton, 1995)

What roles do they have in the ecosystem?

Carolina wrens affect the populations of the insects and spiders they eat, and provide valuable food for their predators. They compete with other cavity-nesting species for nest sites. They also provide habitat for various parasites, including mites, lice, ticks, and blowfly larvae. (Haggerty and Morton, 1995)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

There are no known negative effects of Carolina wrens on humans.

How do they interact with us?

We do not know of any way in which Carolina wrens affect humans.

Are they endangered?

Carolina wrens are very adaptable and are able to live in many different habitats. This ability has helped Carolina wrens to remain common and widespread. There are about 17,000,000 Carolina wrens in the world.

Humans do help Carolina wrens in the northern part of their range where harsh winters can kill a lot of birds. In northern areas, people build nest boxes that the wrens can use for roosting and nesting. (Haggerty and Morton, 1995)

Some more information...

Contributors

Kari Kirschbaum (author, editor), Animal Diversity Web.

Meredith Kurpinski (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, 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

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that generate their own body heat through metabolic processes.

forest

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

insectivore

An animal that eats mainly insects or spiders.

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).

monogamous

Having one mate at a time.

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.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland
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
visual

uses sight to communicate

References

Cornell Lab of Ornithology, 1999. "Carolina Wren (Thryothorus Ludovicianus)" (On-line). Accessed March 14, 2001 at http://birds.cornell.edu/birdhouse/speciesaccounts/CAROLINAWREN.htm.

Haggerty, T., E. Morton. 1995. Carolina Wren (Thryothorus ludovicianus). Pp. 1-20 in A Poole, F Gill, eds. The Birds of North America, Vol. 188. Philadelphia, PA: The Academy of Natural Sciences, and Washington, DC: The American Ornithologists' Union.

Hill Collins, Jr., H., N. Boyajian. 1965. Familiar Garden Birds of America. New York: Harper & Row, Publishers, Inc.

Sauer, J. 1997. "USGS: Science For a Changing World, Patuxent Bird Population Studies - Carolina Wren" (On-line). Accessed March 14, 2001 at http://www.mbr-pwrc.usgs.gov/id/framlst/i7180id.html.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Kurpinski, M. 2001. "Thryothorus ludovicianus" (On-line), Animal Diversity Web. Accessed April 24, 2014 at http://www.biokids.umich.edu/accounts/Thryothorus_ludovicianus/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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