Brown Thrasher - Michigan Breeding Bird Atlas Website

Brown Thrasher (Toxostoma rufum) 

Raymond J. Adams, Jr. 

Manistee Co., MI. 6/21/2009 © Darlene Friedman 

This species sponsored by 

the Audubon Society of Kalamazoo 

(Click to view a comparison of Atlas I to II) 

Anyone familiar with the Brown Thrasher 

during the breeding season is well aware of its 

pugnacity. This colorful mimid presents a fierce 

demeanor when threatened by potential nest 

predators, as I learned at an early age. The 

Brown Thrasher readily throws itself at humans, 

dogs, snakes and other birds (pers. obs.). This 

thrasher is easily identified as few species are 

similar in appearance. There are a handful of 

thrushes with comparable patterns, but all lack 

the long graceful tail and yellow eye. The only 

species which might cause confusion is the 

similar Long-billed Thrasher which overlaps 

with the Brown Thrasher in south Texas. The 

Brown Thrasher breeds from the East Coast to 

the Rocky Mountains and from the Canadian 

Prairie Provinces and the south edge of the 

boreal forest to the Gulf Coast. In winter it 

retires to the southern third of the United States 

with a few birds overwintering each year into 

the northern U.S. This species breeds 

throughout Michigan, although it is less 

common in the Upper Peninsula and rare on Isle 

Royale. 

Distribution 

On careful examination of the Michigan atlas 

map for the Brown Thrasher, this species is 

widespread in the LP, reported from 73% of the 

townships with a near universal distribution in 

the southwestern counties. The prevalence of 

thrashers in southwestern Michigan is 

associated with their preference for deciduousmixed 

shrub upland, shrubby old field, and 

shrub wetland (Eastman 1991). In addition, this 

area of the state has extensive farmland 

bordered by hedgerows and tree-lined 

fencerows, which provide alternative nesting 

cover. Elsewhere in the LP, the Brown 

Thrasher is fairly uniform in distribution. In the 

eastern third of the LP from Lenawee and 

Monroe counties all the way to the Straits of 

Mackinac, there is a north/south corridor where 

this species is sometimes absent. The causes for 

these gaps in occurrence are not obvious from 

looking at a map. During MBBA I, the Brown 

Thrasher was present in every township in 

Oakland and Livingston counties. In MBBA II, 

this species was unrecorded in 21 townships in 

these same two counties. Urbanization, human 

population increases, and the accompanying loss 

of habitat likely explain losses of Brown 

Thrasher in these two counties (and effort 

decreased there from 1,739 hours in MBBA I to 

901 hours in MBBA II). But distribution gaps 

away from large population centers are more 

difficult to explain. 

© 2011 Kalamazoo Nature Center


In the Upper Peninsula, the Brown Thrasher was 

recorded in 270 blocks and 221 townships in 

MBBA I, but only 228 blocks and 186 

townships in MBBA II. The overall distribution 

in the UP in MBBA II has changed little from 

the previous survey. This bird is widely 

distributed north of Wisconsin, especially in 

Menominee, Dickinson, Marquette and Iron 

counties. Elsewhere in the UP, the distribution 

is clumped with large regions where the species 

is apparently absent, presumably because the 

“earlier shrub stages of plant succession” they 

require are missing (Eastman, 1991). 

Breeding Biology 

The adage “timing is everything” is certainly 

relevant when surveying for the Brown 

Thrasher. Males typically return before 

females, by mid April or earlier in the SLP 

(Bent 1948), to establish territory. On arrival, 

they may counter sing with other males in close 

proximity. Singing continues from the tallest 

available perch to attract females as they begin 

to arrive. The song period is not long in 

duration (Cavitt and Haas 2000), but at this time 

the species is easy to locate, especially when 

multiple males are present. Interestingly, males 

sing less frequently when competition is lacking 

(pers. obs.). Brown Thrashers renew singing 

prior to the second brood or following an initial 

nest failure. Once nesting starts the male helps 

incubate and feed the young (Cavitt and Haas 

2000) and the Brown Thrasher becomes much 

less conspicuous. It is not until the young 

fledge and begin following the adults around for 

food that the thrasher again is more easily 

located. Clutch size ranges from 2 to 6 eggs and 

may vary seasonally and regionally. 

Abundance and Population Trends 

(Click to view trends from the BBS) 

The Brown Thrasher was likely present in 

Michigan well before the time of European 

settlement. It was present when Sager published 

the first state bird list in 1839 and was listed by 

each of the authors throughout the rest of the 


19 th and 20 th centuries. It undoubtedly 

benefitted from the increase in human 

settlement and lumbering as suggested by 

Gibbs’ report that it “breeds in all half-cleared 

localities in LP” (1879). Most of the comments 

regarding abundance are vague. Whether you 

read Barrows (1912), who said “summer 

resident of all parts of the state…most abundant 

in the southern half” or Payne (1983) who 

described it as “common in the Lower 

Peninsula, more local and less common in the 

Upper Peninsula”, exactly how common was it 

It probably reached its peak abundance in the 

late 1800s following forest clearing. There is 

little data on actual numbers in Michigan during 

the early 20 th century, but in Illinois the Brown 

Thrasher declined 74% from 1909 through 1958 

(Cavitt and Haas 2000). With the increased use 

of pesticides following World War II, there is 

every reason to expect that trend continued. 

Federal BBS routes from 1966 through 2007 

indicate a decline of more than 80% of Brown 

Thrasher numbers in Michigan (Sauer et al. 

2008), while Kalamazoo County BBS surveys 

suggest an 86% drop from 1970 through 2006. 

Michigan Breeding Bird Atlas data from 1983- 

2008 also indicate a decline. During MBBA I, 

there were nearly 4,100 pairs found in over 

2,500 blocks, while the MBBA II results total 

about 3,500 pairs in 1,845 blocks. Clearly, the 

Brown Thrasher is on a downward trend. 

Conservation Needs 

While the Brown Thrasher is neither threatened 

nor endangered, the rapid population decline 

over the past 50 to 100 years is cause for alarm. 

As with other declining species which occupy 

similar habitat or rely on similar food, a number 

of hypotheses have been proposed for the 

causes. Following the expansion of pesticide 

use after World War II, the Brown Thrasher 

suffered increased visible mortality as well as 

indirect mortality in and around agricultural 

operations (Cavitt and Haas 2000). This no 

doubt continues today. Collisions are known to 



be another serious mortality factor. While 

stationary objects such as towers and windows 

are well known obstacles, automobiles and 

trucks cause heavy mortality. During Atlas 

surveys in southwestern Michigan, Brown 

Thrasher road kills including young were noted 

on occasion (pers. obs.). Because this bird is a 

short distance migrant, it is less likely to be 

exposed to severe weather in migration. Harsh 

winters in the south have been known to cause 

major impacts. Habitat degradation and loss 

may be the greatest problem of all. 

Habitat protection may be the most important 

management opportunity. Efforts could include 

protecting hedgerows, letting fields go fallow, 

providing brush cover along agricultural field 

edges, and designing housing developments 

where portions of the natural areas are salvaged. 

Because roadside mortality has become an 

issue, finding ways to alter roadsides so that 

wildlife is provided greater protection would 

help many bird species, not just the Brown 

Thrasher. All children deserve the chance to 

discover the Brown Thrasher’s defensive 

behaviors for themselves. 

Literature Cited 

Barrows, W.B. 1912. Michigan bird life. 

Special Bulletin. Michigan Agricultural 

College, East Lansing, Michigan, USA. 

Bent, A.C. 1948. Life Histories of North 

American Nuthatches, Wrens, Thrashers, 

and Their Allies. U.S. National Museum 

Bulletin 195. 

Cavitt, J.F., and C.A. Haas. 2000. Brown 

Thrasher (Toxostoma rufum). Account 557 

in A. Poole and F. Gill, editors. The Birds 

of North America. The Birds of North 

America, Inc., Philadelphia, Pennsylvania, 

USA. 

Eastman, J. 1991. Brown Thrasher (Toxostoma 

rufum). Pages 364-365 in R. Brewer, G.A. 

McPeek, and R.J. Adams, Jr. The Atlas of 

Breeding Birds of Michigan. Michigan 


State University Press, East Lansing, 

Michigan, USA. 

Gibbs, M. 1879. Annotated list of the birds of 

Michigan. Bulletin of the US Geological 

and Geographical Survey of the Territories 

5:481-497. 

Payne, R.B. 1983. A Distributional Checklist 

of the Birds of Michigan. Miscellaneous 

Publication 164. University of Michigan 

Museum of Zoology, Ann Arbor, Michigan, 

USA. 

Sager, A. 1839. Report of Doctor Abraham 

Sager, zoologist of Geological Survey. 

House Documents of the State of Michigan: 

410-421. 

Sauer, J.R., J.E. Hines, and J. Fallon. 2008. 

The North American Breeding Bird Survey, 

Results and Analysis 1966-2007. Version 

5.15.2008. USGS Patuxent Wildlife 

Research Center, Laurel, Maryland, USA. 

Suggested Citation 

Adams, R.J., Jr. 2011. Brown Thrasher 

(Toxostoma rufum). In A.T. Chartier, J.J. 

Baldy, and J.M. Brenneman, editors. The 

Second Michigan Breeding Bird Atlas. 

Kalamazoo Nature Center, Kalamazoo, 

Michigan, USA. Accessed online at: 

.

Brown Thrasher - Michigan Breeding Bird Atlas Website

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