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brown thrasher

Toxostoma rufum

What do they look like?

Adult brown thrashers have reddish upperparts and whitish underparts, with a long, black tail. They have long, straight bills and yellow eyes. Males and females are alike in size and color. The young appear the same as adults, except their upperparts are spotted and their eyes are gray.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    89 (high) g
    3.14 (high) oz
  • Average mass
    68.8 g
    2.42 oz
  • Range length
    235 to 305 mm
    9.25 to 12.01 in
  • Range wingspan
    94 to 111 mm
    3.70 to 4.37 in

Where do they live?

Brown thrashers are found from southeastern Canada through eastern, central, and southeastern United States. They are found in the Nearctic region. Brown thrashers are the only thrasher species east of the Rocky Mountains and central Texas. During the summer brown thrashers are found from southern Canada south to east central Texas. Brown thrashers migrate short distances between the summer and winter seasons. They migrate at night. Birds in the northern part of their range migrate into the southern parts of their range.

What kind of habitat do they need?

Brown thrashers are found in warm, dry habitats, such as warm forest edges and dense thickets. They are also found in suburban and agricultural areas. (Cavitt and Haas, 2000; Peterson, 1999; Peterson, 2001)

How do they reproduce?

When male brown thrashers arrive at the breeding grounds in spring they establish a territory. Breeding begins in February and March in the southern parts of their range and from May to June in the north. Once the male and female form a bond, they begin to build a nest. Mates find each other with calls, most commonly using a call similar to a "tick" or "tchuck".

Brown thrashers start breeding from February to June, depending on the area where they are found. Brown thrashers lay 3 to 5 eggs each breeding season. Incubation takes about two weeks, once the eggs have hatched, nestlings take from 9 to 13 days to fledge. Independence is reached 17 to 19 days later.

  • How often does reproduction occur?
    Brown thrashers breed once yearly.
  • Breeding season
    Breeding season varies geographically. Southern populations breed in February and March, northern populations birds breed in May and June
  • Range eggs per season
    3 to 5
  • Average eggs per season
    4
    AnAge
  • Range time to hatching
    11 to 14 days
  • Range fledging age
    9 to 13 days
  • Range time to independence
    17 to 19 days

Both parents incubate, brood, and feed nestlings. They incubate by sitting tightly on the nest and slip off when disturbed. During the incubation period, the female does the majority of the incubating. Both parents feed the chicks. (Cavitt and Haas, 2000; Ehrlich, et al., 1988)

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

How long do they live?

Only about 35% of brown thrashers live through their first and second years, about 50% between second and third years, and 75% between the third and fourth years. Diseases, parasites, and cold exposure can kill these birds. The longest known lifespan in the wild is twelve years and in captivity, ten to twelve years.

  • Range lifespan
    Status: wild
    12 (high) years
  • Range lifespan
    Status: captivity
    10 to 12 years
  • Typical lifespan
    Status: wild
    11.34 to 17.61 years
  • Average lifespan
    Status: wild
    14.14 years
  • Average lifespan
    Status: captivity
    12 years

How do they behave?

Brown thrashers are usually territorial and are found in pairs or with offspring during the breeding season. They compete with other birds for habitat and nesting areas. This competition results in hostile encounters with birds like gray catbirds (Dumetella carolinensis). Mostly it is males that are aggressive towards other birds. During winters brown thrashers often make other birds move out of their feeding areas. The name "thrasher" may come from the bird's habit of thrashing ground litter with its bill. Migration is over short distances and at night.

  • Range territory size
    5000 to 11300 m^2

Home Range

Territory-mapping studies indicate variation in territory densities. Most activites of a pair are confined to territories. (Cavitt and Haas, 2000)

How do they communicate with each other?

Brown thrashers communicate mainly with calls. They copy the sounds of other birds and are known for their beautiful, complex songs. Males have many kinds of songs, more than any other kind of North American bird, as many as 1100 types of songs. At young ages, brown thrashers use "alarm noises". They also use their vision and sense of touch to find and handle food.

  • Other Communication Modes
  • mimicry

What do they eat?

Brown thrashers eat insects, mainly beetles and other arthropods, fruits, and nuts. They forage for food on the ground in leaf litter below trees and shrubs. These birds sweep the soil and leaf litter with rapid side-to-side movements of their beak. After sweeping a few times, they probe the soil and litter with their beaks.

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

What eats them and how do they avoid being eaten?

Gray catbirds (Dumetella carolinensis) have been documented visiting brown thrasher nests to break the eggs. Two hypotheses are proposed to explain this heterospecific egg destruction behavior: resource competition and egg predation. These birds both live in shrubs and have similar timing in breeding. They compete for the resources of this habitat. Once the catbird has broken the egg, usually it will consume the contents. This egg consumption is consistent with the proposed egg predation hypothesis. The eggs of brown thrashers are also preyed on by many species of snakes. Adults and nestlings are preyed on by falcons. (Cavitt and Haas, 2000; Rivers and Sandercock, 2004)

To respond to predation, brown thrashers have a few natural defenses. Adults are aggressive and often chase predators from the nest. Adults will use their bill to hit predators, these are large birds and they can cause significant damage to small and medium-sized predators. Other defenses include flapping theirwings and vocalizations. (Cavitt and Haas, 2000; Rivers and Sandercock, 2004)

Gray catbirds sometimes visit brown thrasher nests and break and eat the eggs. The eggs of brown thrashers are also preyed on by many species of snakes. Adults and nestlings are preyed on by falcons.

Brown thrashers are aggressive and often chase predators from their nests. Adults will use their bills to hit predators, they also flap their wings at predators and use alarm calls.

What roles do they have in the ecosystem?

Ecosystem roles include competition with other birds for nesting sites and resources. Also these birds are prey for many snakes and other birds. (Cavitt and Haas, 2000; Ehrlich, et al., 1988; "Mockingbirds", 1985; Fergus, 2004)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • ticka (Ixodes dentatus)
  • hematophagous larvae (Protocalliphora metallica, P. shannoni)

Do they cause problems?

Brown thrashers can be significant pests in fruit orchards and crop fields. (Cavitt and Haas, 2000; Cavitt and Haas, 2000)

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

Brown thrashers are one of the best and most spectacular singers of all North American birds. Avid bird watchers enjoy the chance to see and hear these birds. (Ehrlich, et al., 1988)

  • Ways that people benefit from these animals:
  • ecotourism
  • research and education

Are they endangered?

Brown thrashers are not listed as threatened or endangered in any part of their range. No management actions are known to increase or maintain populations. Dangers include pesticides, collisions with structures, and some degradation of habitats. These effects have yet to become harmful enough to cause concern. (Cavitt and Haas, 2000)

Some more information...

Brown thrashers belong to the mimic thrush family, Mimidae. They are among the most vocal birds and often mimic other species. Other birds in this group include northern mockingbirds (Mimus polyglottos) and gray catbirds (Dumetella carolinensis).

The best time to observe these birds is in April, before nest sites are established. During this time males sing on high branches to attract mates. (Cavitt and Haas, 2000; Ehrlich, et al., 1988; Fergus, 2004)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Phillip Gray (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

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

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.

chemical

uses smells or other chemicals to communicate

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

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

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).

migratory

makes seasonal movements between breeding and wintering grounds

mimicry

imitates a communication signal or appearance of another kind of organism

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.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

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

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

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.

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

visual

uses sight to communicate

References

Equinox (Oxford) Ltd. 1985. Mockingbirds. Pp. 360-361 in C Perrins, A Middleton, eds. The Encyclopedia of Birds. New York: Facts On File Publications.

Cavitt, J., C. Haas. 2000. Toxostoma rufum brown thrasher. Pp. 1-28 in The Birds of North America, Vol. 14, 541-560 Edition. Philadelphia, PA: The Birds of North America, Inc..

Dunning, J. 1993. CRC handbook of avian body masses. Boca Raton, FL: CRC Press.

Ehrlich, P., D. Dobkin, D. Wheye. 1988. The birder's handbook a field guide to the natural history of north american birds. New York, New York: Simon and Schuster Inc..

Fergus, C. 2004. "Gray Catbird, Northern Mockingbird and Brown Thrasher" (On-line). Pennsylvania Game Commision. Accessed November 12, 2006 at http://www.pgc.state.pa.us/pgc/cwp/view.asp?a=458&q=150398.

Godfrey, W. 1986. The Birds of Canada. The Birds of Canada, Rev. ed. Edition. Ottawa, ON: National Museum of Natural Science.

Howard, R., A. Moore. 1991. A Complete Checklist of the Birds of the World. San Diego, CA: Academic Press Inc..

Peterson, A. 2001. Predicting species’ geographic distributions based on ecological niche modeling. The Condor, 103 3: 599-605. Accessed October 15, 2006 at http://0-www.bioone.org.ariadne.kzoo.edu/perlserv/?request=get-document&doi=10.1650%2F0010-5422%282001%29103%5B0599%3APSGDBO%5D2.0.CO%3B2#I0010-5422-103-3-599-PETERSON2.

Peterson, A. 1999. Sensitivity of distributional prediction algorithms to geographic data completeness. Ecological Modeling, 117: 159-164.

Rivers, J., B. Sandercock. 2004. Predation by gray catbird on brown thrasher eggs. The Southwestern Naturalist, 49/1: 101-103.

Robbins, C., B. Bruun, H. Zim. 1983. A guide to filed identification birds of North America. New York, New York: Western Publishing Company, Inc..

 
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Gray, P. 2007. "Toxostoma rufum" (On-line), Animal Diversity Web. Accessed April 18, 2014 at http://www.biokids.umich.edu/accounts/Toxostoma_rufum/

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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