Winter Wren (Troglodytes hiemalis) Skye Christopher G. Haas
Iron Co., MI 5/30/2009 © Elizabeth Rogers (Click to view a comparison of Atlas I to II)
Sporting a voice larger than the bird itself, this It is likely that densities were negatively charming sprite is a vocal acrobat with a affected by the extensive white pine harvest of dizzying song that rings out from moist, dark the second half of the 1800s, although forests of the north. Arthur C. Bent (1948) was unharvested hemlock and cedar communities moved to describe this champion songster’s provided enough refugia to maintain a stable utterances as: “Wonderful…charming… population (Brewer 1991). Barrows (1912) marvelous…startling…entrancing…copious, reported the species to be common in the UP rapid, prolonged and penetrating, having a great and NLP, and nesting evidence was obtained variety of the sweetest tones, and uttered in a south to Montcalm, Kent and Ottawa Counties. rising and falling or finely undulating He also speculated that both nesting and melody…as if the very atmosphere became wintering were possible in the lower tier of resonant… [a] gushing melody, which seems at counties, although no conclusive evidence once expressive of the wildest joy and the existed. tenderest sadness”. Winter Wrens (along with Pacific Wren in western North America), were MBBA I shows a distribution similar to the one recently spilt from the Old World species, described by Barrows (1912). Widespread simply known as the Wren. Winter Wrens can across the UP, BBS data showed the highest be found from northeastern British Columbia densities could be found in the unbroken forests and northern Alberta across Canada to of the Ottawa National Forest. Their range in Newfoundland, south to Minnesota east to New the LP was primarily northern, stretching England and south in the Appalachians to southwest from Lake Huron to the Manistee northeastern Georgia (Chesser et al. 2010). National Forest to along the tension zone into Muskegon County. Winter Wrens were mostly Distribution absent from around the agricultural lands of the There was probably very little change in the Saginaw Bay, though small disjunct populations status and distribution of the Winter Wren in were found in Tuscola/Lapeer Counties and Michigan from the establishment of mature Allegan County. However, breeding was not forest communities after the last glacial period confirmed in the SLP. until the mid-19th century, with birds residing over the northern 2/3 of the state, south to the MBBA II showed a slight overall increase from tension zone. MBBA I in the number of recorded townships
© 2011 Kalamazoo Nature Center Winter Wren (Troglodytes hiemalis) Skye Christopher G. Haas
(from 32% to 35%), but this increase was only and mossy substrates and rarely on the branches visible in the UP, where the percentage jumped of a standing or fallen tree (Hejl 2002). Egg- from 62% to 74%. The NLP showed a decrease laying can begin as soon as late April, and atlas from 35% to 34% and, in the SLP, the workers in Wisconsin found fledgling young on distribution was reduced from 3% to 1%. the early date of 26 May (Wolf and Howe Breeding confirmation also retreated northward 2006). Clutch size is typically five to seven to the next tier of counties with the eggs which are incubated for 14-16 days. southernmost confirmed breeding occurring in Young generally remain in the nest for 19 days, Crawford and Ogemaw Counties. Confirmation and are fed by both parents, even after leaving is difficult for this secretive species, and there the nest (Hejl 2002, Wolf and Howe 2006). One were only confirmed breeding records for 36 to two broods a summer are possible, not townships, despite being recorded in a total of including re-nesting attempts (Hejl 2002). 669 townships. Abundance and Population Trends Conifer forests, particularly spruce bogs, cedar (Click to view trends from the BBS) swamps and old-growth pine/hemlock forests Partners in Flight (PIF 2007) estimates that are favored habitats, though in Upper Michigan, there are 160,000 Winter Wrens in Michigan, the species can be commonly found in moist and this represents 0.4% of the global mature/old-growth mesic deciduous forests, as population (which also includes the super- long as there is a water component (usually a species complex of Pacific and Eurasian Wren). forest stream that provides a cooler BBS data for eastern North America shows the microclimate), dead-fall, a lush undergrowth highest percentage of birds in the Closed Boreal and often glacial debris in the form of boulders Forests, while some of the lowest numbers are and stone outcroppings. Winter Wrens require in the Great Lakes Transitional zones (Sauer et structurally complex forests, with much dead al. 2008). National BBS data trends from 1966 wood in the form of fallen trees with exposed to 2008 showed only a 0.9% increase with a root masses and are frequently associated with more recent trend of a significant annual water, particularly streams, but also bogs, decrease of 3.7% from 2003-2008, though this swamps and lake edges (Hejl et al. 2002). Also dataset includes Pacific Wren (Ziolkowski et al important are broken openings or edges in the 2010). forest, and heavily vegetated cover that includes shrubs, ferns, and mosses (Ewert 1991, Hejl et It is certainly a common bird in appropriate al. 2002). habitat in the UP, and one of the most abundant birds in summer on Manitou Island, Keweenaw Breeding Biology County, where in June 2002, 35 were recorded Winter Wrens return to their breeding territories on 21 of 22 point counts. This tiny bird migrates as early as late March, but more typically in over Lake Superior and has been observed early to mid-April (Nelson 1994). In years of flying in off of the lake in the fall in Keweenaw substantial lingering snow cover, all birds may County (Binford 2006). not be back on territory until early May. Males arrive first and build one to several nests, of Numbers of Winter Wrens seem to be which the female selects one and lines the increasing in the state, or at least a higher rate of interior (Hejl et al. 2002). The nest is often detection has been established. It is possible that domed, and is usually placed within the root the increase in observations in the UP may be structure of an up-turned tree. Nests are also related to better atlas coverage in MBBA II placed in or under creek banks, decaying logs, rather than an actual increase in birds. However the obvious decline of birds in the LP, even as
© 2011 Kalamazoo Nature Center Winter Wren (Troglodytes hiemalis) Skye Christopher G. Haas forests are reaching a level of preferred habitat Chesser, R.T., R.C. Banks, F.K. Barker, C. maturation as farming practices are abandoned, Cicero, J.L. Dunn, A.W. Kratter, I.J. is troubling. Lovette, P.C. Rasmussen, J.V. Remsen Jr., J.D. Rising, D.F. Stotz, and K. Winker. Conservation Needs 2010. Fifty-first Supplement to the The absence of deer on Manitou Island, American Ornithologists' Union Check-List Keweenaw County, has demonstrated how of North American Birds. Auk 127(3): 726- ample evergreen shrubbery (yew) can benefit 744. Winter Wrens (Binford 2006, pers. obs). Deer Ewert, D.N. 1991. Winter Wren. In Brewer, R., herds on the mainland frequently over-browse in G.A. McPeek, and R.J. Adams Jr. (eds.). cedar swamps and other favored Winter Wren 1991. The Atlas of Breeding Birds of breeding locations. Extensive logging also Michigan. Michigan State University Press. would negatively affect this species, especially East Lansing, MI. in boreal habitat where Winter Wrens are Hejl, S.J., J.A. Holmes, and D.E. Kroodsma. primarily found in mature to old-growth forest. 2002. Winter Wren (Troglodytes Winter Wrens have been shown to be negatively troglodytes). In The Birds of North America, affected by forest fragmentation, and this should No. 623 (A. Poole and F. Gill, eds.). The be reflected in any forest management plan Birds of North America, Inc., Philadelphia, (Hejl 2002, Wolf and Howe 2006). PA. Nelson, C. 1994. Winter Wren. In McPeek, As a species intrinsically tied to the boreal G.A., and R.J. Adams (eds.). 1994. The forests, the Winter Wren is another bellwether Birds of Michigan. Indiana University Press. of the disappearance of this biome. A Winter Indianapolis, IN. Wren’s habitat is as delightful as its song, and if Partners in Flight (PIF). 2007. PIF Landbird both these spectacular joys of the north woods Population Estimates Database [web were to disappear, we will have lost much application]. Version 2004. Rocky indeed. Mountain Bird Observatory.
© 2011 Kalamazoo Nature Center