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Toxostoma rufum
brown thrasher


By Phillip Gray

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Aves
Order: Passeriformes
Family: Mimidae
Genus: Toxostoma
Species: Toxostoma rufum
Members of this Species

Geographic Range

Brown thrashers are found from southeastern Canada through eastern, central, and southeastern United States. Brown thrashers are the only thrasher species east of the Rocky Mountains and central Texas. During the breeding season brown thrashers primarily inhabit areas of southern Canada south to east central Texas. Migration is over short distances and at night. In winter, these birds migrate from the northern parts of their range into the southern parts of their range. (Howard and Moore, 1991; Robbins, et al., 1983)

Biogeographic Regions
nearctic (Native )

Habitat

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)

Habitat Regions
temperate ; terrestrial

Terrestrial Biomes
forest ; scrub forest

Other Habitat Features
suburban ; agricultural ; riparian

Physical Description

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)

Adults have rufous upperparts and white underparts with a long, black tail. They have long, straight bills and yellow eyes. Males and females are alike in size and coloration. They are from 23.5 cm to 30.5 cm long, with wingspans of 9.4 to 11.1 cm long. The young appear the same except their upperparts are spotted and their eyes are gray. There are two sub-species, brown thrashers (T. rufum rufum) and long-billed thrashers (T.rufum longirostre). Long-billed thrashers are unique in their dull upperparts, gray head, orange eye, and long, straight bill. (Cavitt and Haas, 2000; Dunning, 1993; Godfrey, 1986)

Other Physical Features
endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism
sexes alike

Reproduction

When males arrive at the breeding grounds they establish a territory. In the southern parts of their range breeding starts in February and March, in the northern parts, breeding starts in May and June. Soon after this, pairs are formed and they begin to build a nest. Mates find each other with calls, most commonly using a call similar to a "tick" or "tchuck". Once the bond is formed and the nest is built, the pair will mate. (Cavitt and Haas, 2000; Fergus, 2004)

Mating System
monogamous

Breeding interval
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
[External Source: AnAge]

Range time to hatching
11 to 14 days

Range fledging age
9 to 13 days

Range time to independence
17 to 19 days

Brown thrasher breeding seasons vary with geographic region. Birds in the southern region breed from February to March; while those in the northern region breed from May to June. Brown thrashers lay three to five 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. (Cavitt and Haas, 2000; Ehrlich, et al., 1988)

Key Reproductive Features
seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

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)

Lifespan/Longevity

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

Year-to-year survival is age dependent for brown thrashers. Survival rate is approximately 35% for their first and second years, 50% between second and third years, and 75% between third and fourth years. Limitations to lifespan include disease (for example Salmonella tymphimurium), parasitism, and sometimes exposure to cold temperatures. The longest known lifespan in the wild is twelve years and in captivity, ten to twelve years. (Cavitt and Haas, 2000; Ehrlich, et al., 1988)

Behavior

Range territory size
5000 to 11300 m^2

These birds 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). Most often these encounters are instigated by males. During winters brown thrashers often displace other birds from 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. (Cavitt and Haas, 2000; Fergus, 2004)

Key Behaviors
terricolous; flies; diurnal ; migratory ; territorial

Home Range

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

Communication and Perception

Brown thrashers communicate mainly with vocalizations. They use mimicry extensively as well and are well known for their songs. Males have the largest documented song repertoire of all North American bird. This includes over 1100 types of songs. At young ages, birds most commonly use "alarm noises". Primary modes of perception include visual and tactile. Brown thrashers use mainly vision to find food and their tactile abilities to search for and manipulate food. (Cavitt and Haas, 2000; Ehrlich, et al., 1988)

Communication Channels
acoustic

Other Communication Modes
mimicry

Food Habits

Brown thrashers eat insects, primarily 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 that scatter leaves. After sweeping a few times, they will probe the soil and litter with their beaks. (Cavitt and Haas, 2000)

Primary Diet
omnivore

Animal Foods
insects

Plant Foods
seeds, grains, and nuts; fruit

Predation

Known Predators


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)

Ecosystem Roles

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/Parasitic Species

Economic Importance for Humans: Positive

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)

Positive Impacts
ecotourism ; research and education

Economic Importance for Humans: Negative

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

Negative Impacts
crop pest

Conservation Status

IUCN Red List of Threatened Species [Link]
Least Concern
More Information

US Migratory Bird Act [Link]
Protected

US Federal List [Link]
No special status

CITES [Link]
No special status

State of Michigan List [Link]
No special status

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)

Other Comments

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)

For More Information

Find Toxostoma rufum information at

Contributors

Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.

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

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..

To cite this page: Gray, P. 2007. "Toxostoma rufum" (On-line), Animal Diversity Web. Accessed June 01, 2012 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Toxostoma_rufum.html

Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

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