Toxostoma rufum

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.

• Biogeographic Regions
• nearctic nearctic
  • native 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.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• scrub forest scrub forest

• Other Habitat Features
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry 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.

• Mating System
• monogamous monogamous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

• Parental Investment
• altricial 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

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.

Behavior

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.

• Key Behaviors
• terricolous
• flies
• diurnal diurnal
• motile motile
• migratory migratory
• territorial territorial

Home Range

Territory-mapping studies indicate variation in territory densities. Most activites of a pair are confined to territories.

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.

• Communication Channels
• acoustic acoustic

• Other Communication Modes
• mimicry mimicry

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• omnivore omnivore

• Animal Foods
• insects

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

Predation

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.

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.

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.

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.

• Positive Impacts
• ecotourism ecotourism
• research and education

Economic Importance for Humans: Negative

Brown thrashers can be significant pests in fruit orchards and crop fields.

• Negative Impacts
• crop pest

Conservation 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.

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.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

References

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..

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