Carolina Wren (Thryothorus ludovicanianus) Michael J. Hamas
Kensington Metro Park, Oakland Co. MI. November, 2008 © Willie McHale
(Click to view a comparison of Atlas I to II)
Even in Michigan, nothing could be finer than Wisconsin (Cutright 2006) and Michigan, Carolina Wrens are concentrated in the three to hear the clear ringing song of a Carolina southernmost tiers of counties. In neighboring Wren in the morning, particularly after a harsh Ontario, birds are found south of the Canadian winter. Although they are resident species Shield, especially near the shorelines of the throughout their range, Carolina Wrens are lower Great Lakes (Read 2007). vulnerable to extreme periods of cold but can survive if they find adequate food (Leberman Carolina Wrens’ sedentary behavior is 1976, Robbins et al. 1986). Sometimes northern illustrated by their long term occupancy of populations decline markedly after severe townships in the SLP. Only eight townships in winters, but gradually increasing winter which birds occurred during MBBA I were temperatures over the last century may be vacant during MBBA II. Dispersal appears to be responsible for the northward range expansion through river valleys (Smith 2008) where seen in the mid-1900s (Haggerty and Morton bottomland habitat may provide access to more 1995). It is also likely that fragmentation, reliable food resources, particularly during clearing of forests, and increased bird feeding winter months. In addition, expansion of the activity have contributed to range expansion of species may be related to mild winters and the species as well as its ability to become feeders (Orton 1998). Since MBBA I, Carolina established farther north. What was once a rare Wrens have exhibited a 755% increase in the bird in Michigan is now being seen with ever number of occupied townships statewide.. increasing frequency.
Breeding Biology Distribution Maintaining territories and pair bonds year First listed for Michigan by Fox (1853), round, Carolina Wrens may begin to lay eggs as Barrows (1912) summarized continuous but early as mid-April in southern Michigan sporadic records of Carolina Wrens in the SLP (Arnold 1956). Two clutches are typical but a during the 1800s. Wood (1951) considered the third may be produced in a given year. Nesting species a rare resident north to Livingston and sites are diverse: natural cavities, woodpecker Barry counties, although there were isolated holes, birdhouses, among the roots of upturned reports of birds occurring farther north. In both
© 2011 Kalamazoo Nature Center Carolina Wren (Thryothorus ludovicanianus) Michael J. Hamas trees, stone walls, and nooks in human Conservation Needs dwellings or outbuildings have been reported At the periphery of their range, Carolina Wrens (Harrison 1975). Only females incubate, but in Michigan are likely to experience population both parents feed young. The family unit fluctuations, particularly after winters remains together after fledging unless the characterized by severe cold, heavy snow, and female initiates another clutch (Haggerty and lasting ice. Nevertheless, given the species’ Morton 1995). Breeding may extend into early apparent ability to disperse and to colonize a autumn. wide array of habitats, conservation action is likely not warranted. Abundance and Population Trends (Click to view trends from the BBS) Literature Cited Assessing year round status of the Carolina Wren throughout its range in North America has Arnold, K. 1956. Nesting of the Carolina Wren been enhanced by visualization tools developed in Kalamazoo County, Michigan. Jack-Pine by the Avian Knowledge Network (AKN) Warbler 34:139-140. providing a graphic picture of not only Barrows, W.B. 1912. Michigan Bird Life. distribution but also where the species occurs Special Bulletin . Michigan Agricultural with highest frequency or not at all (Sullivan et College, East Lansing, Michigan, USA. al. 2009). Another measure of population trends Cutright, N.J. 2006. Carolina Wren includes BBS data which indicate that Carolina (Thryothorus ludovicianus). Pages 330-331 Wrens have increased by more than four percent in N.J. Cutright, B.R. Harriman, and R.W. annually throughout the Midwest as well as in Howe 2006. Atlas of the Breeding Birds of Michigan since MBBA I (Sauer et al. 2008). Wisconsin. Wisconsin Society for Statewide, there was more than an eight-fold Ornithology. Waukesha, Wisconsin, USA. increase in percentage of occupied blocks Fox, C. 1853. The Birds of Michigan. The during MBBA II, and confirmed breeding in the Peninsular Journal of Medicine and the SLP increased by more than 70%. Carolina Collateral Sciences, 1(4):159-63; (8): 352- Wrens are not yet abundant, but populations are 353. increasing, particularly in the three or four Haggerty, T.M. and E.S. Morton. 1995. southernmost tiers of counties. There were 216 Carolina Wren (Thryothorus ludovicianus). townships in which wrens occurred during The Birds of North America Online. MBBA II but not in MBBA I. There was Cornell Lab of Ornithology. breeding evidence in every township of Monroe
© 2011 Kalamazoo Nature Center Carolina Wren (Thryothorus ludovicanianus) Michael J. Hamas
Beck, D. Lepage, and A.R. Courier, editors. Wood, N.A. 1951. The Birds of Michigan. Atlas of the Breeding Birds of Ontario, Miscellaneous Publication 75. University of 2001-2005. Bird Studies Canada, Michigan Museum of Zoology, Ann Arbor, Environment Canada, Ontario Field Michigan, USA. Naturalists, Ontario Ministry of Natural Resources, and Ontario Nature, Toronto, Suggested Citation Canada. Robbins, C.S., D. Bystrak, and P.H. Geissler. Hamas, M.J. 2011. Carolina Wren (Thryothorus 1986. The Breeding Bird Survey: the First ludovicanianus). In A.T. Chartier, J.J. 15 years, 1965-1979. U.S. Fish and Wildlife Baldy, and J.M. Brenneman, editors. The Service. Research Publication 157. Second Michigan Breeding Bird Atlas. Washington, D.C., USA. Kalamazoo Nature Center. Kalamazoo, Sauer, J.R., J.E. Hines, and J. Fallon. 2008. Michigan, USA. Accessed online at: The North American Breeding Bird Survey,
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