Pacific Wren Troglodytes pacificus Scientific name definitions

From beneath the tangles and fallen trees, darting back-and-forth in the moist and mossy understory, the Pacific Wren sings loudly from its favourite perches and “seems as much a part of the forest floor as the mosses, huckleberry vines, huge logs, and upturned roots of his surroundings” (Taylor and Shaw 1927 Taylor, W. P. and W. T. Shaw. (1927). Mammals and birds of Mount Rainier National Park. Nat Park Service of US Dept Int. Close ). A superb songster—the “pinnacle of song complexity” (Kroodsma 1980 Kroodsma, D. E. (1980). Winter Wren singing behavior: a pinnacle of song complexity. Condor 82:357-365. Close )—it is more often heard than seen. It is a small, brown, cryptically-colored wren that generally inhabits dark, moist coniferous forests in western North America, although it can be found breeding on cliff faces on treeless islands of Alaska and the Aleutians.

Until recently the Pacific Wren, the Winter Wren (Troglodytes hiemalis) in eastern North America, and the Eurasian Wren (or “the Wren” in Europe; T. troglodytes) were together recognized as a single species. Patterns of genetics (Drovetski et al. 2004 Drovetski, S. V., R. M. Zink, S. Rohwer, I. V. Fadeev, E. V. Nesterov, I. Karagodin, E. A. Koblik and Y. A. Red'kin. (2004). Complex biogeographic history of a Holarctic passerine. Proceedings of the Royal Society of London Series B-Biological Sciences 271 (1538):545-551. Close ) and vocalizations (Kroodsma 1980 Kroodsma, D. E. (1980). Winter Wren singing behavior: a pinnacle of song complexity. Condor 82:357-365. Close , Kroodsma and Momose 1991 Kroodsma, D. E. and H. Momose. (1991). Songs of the Japanese population of the Winter Wren (Troglodytes troglodytes). Condor 93:424-432. Close , Kroodsma and Brewer 2005 Kroodsma, D. E. and D. Brewer. (2005). "Family Troglodytidae (wrens)." In Handbook of the birds of the world, edited by J. del Hoyo, A. Elliott and D. A. Christie, 356-447. Barcelona: Lynx Edicions. Close , Toews and Irwin 2008 Toews, D. P. L. and D. E. Irwin. (2008). Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. Molecular Ecology 17 (11):2691-2705. Close ) demonstrate, however, that the similarities in breeding plumage and morphometric traits conceal deep divides within this group. In particular, research from an area of range overlap between T. pacificus and T. hiemalis in western Canada indicates that the two are genetically and phenotypically distinct where they co-occur and that the strong differences noted in their song, which are maintained in this area of range contact, provide a potentially important reproductive barrier between the two (Toews and Irwin 2008 Toews, D. P. L. and D. E. Irwin. (2008). Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. Molecular Ecology 17 (11):2691-2705. Close ).

The Pacific Wren breeds in temperate forests west of the eastern foothills of the Rocky Mountains, ranging from California and Utah to the southern coast of Alaska and the Aleutian Islands. There are seven currently recognized subspecies, two of which occur throughout its mainland distribution, with the rest of the subspecies inhabiting islands off the Alaskan coastline.

The species is unique among North American wrens in its association with old-growth forests. It uses old-growth structures (snags, root masses, downed trees, and the bases of large standing trees) for nesting, foraging, and roosting. Breeding territories are primarily found in forests along rivers and streams and, at least in the rainforests along the Pacific Coast, the presence of Pacific Wrens is correlated with riparian areas enriched with salmon-derived nutrients (Field and Reynolds 2011 Field, R. D. and J. D. Reynolds. (2011). Sea to sky: Impacts of residual salmon-derived nutrients on estuarine breeding bird communities. Proceedings of the Royal Society B-Biological Sciences 278 (1721):3081-3088. Close ). Clear-cutting and some types of partial logging reduce habitat suitability for the Pacific Wren, which tends to avoid forest edges, and it is one of a number of species that is likely harmed by forest fragmentation in western North America (Brand and George 2001 Brand, L. A. and T. L. George. (2001). Response of passerine birds to forest edge in coast redwood forest fragments. Auk 118 (3):678-686. Close ). Based on habitat change from pre-settlement times, Pacific Wren numbers are estimated to have declined in some regions Raphael et al. 1988 Raphael, M. G., K. V. Rosenberg and B. G. Marot. (1988). Large-scale changes in bird populations of Douglas-fir forests, northwestern California. Bird Conserv. 3:63-83. Close ) and many recent trends (from 1999–2009) indicate some populations in Washington and British Columbia are decreasing (Sauer et al. 2011b Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr., D. J. Ziolkowski, and W. A. Link. 2011. The North American breeding bird survey, results and analysis 1966-2010 (Version 12.07.2011b). USGS Patuxent Wildlife Research Center, Laurel, MD, USA. Close ). Most monitoring methods are not particularly well suited for tracking Pacific Wren numbers and questions remain about how habitat alteration and future climate change will affect this species (McRae et al. 2008 McRae, B. H., N. H. Schumaker, R. B. McKane, R. T. Busing, A. M. Solomon and C. A. Burdick. (2008). A multi-model framework for simulating wildlife population response to land-use and climate change. Ecological Modelling 219 (1-2):77-91. Close ). Further research is recommended to address these questions as well as a number of other knowledge gaps.

Thorough studies have been conducted on the Pacific Wren in North America, including: Rice et al. 1999b Rice, N. H., A. T. Peterson and G. Escalona-Segura. (1999b). Phylogenetic patterns in montane Troglodytes wrens. Condor 101:446-451. Close , Drovetski et al. 2004 Drovetski, S. V., R. M. Zink, S. Rohwer, I. V. Fadeev, E. V. Nesterov, I. Karagodin, E. A. Koblik and Y. A. Red'kin. (2004). Complex biogeographic history of a Holarctic passerine. Proceedings of the Royal Society of London Series B-Biological Sciences 271 (1538):545-551. Close , Gomez et al. 2005, and Toews and Irwin 2008 Toews, D. P. L. and D. E. Irwin. (2008). Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. Molecular Ecology 17 (11):2691-2705. Close on systematics; Kroodsma 1980 Kroodsma, D. E. (1980). Winter Wren singing behavior: a pinnacle of song complexity. Condor 82:357-365. Close , Van Horne 1995 Van Horne, B. (1995). Assessing vocal variety in the Winter Wren, a bird with a complex repertoire. Condor 97:39-49. Close , and Toews and Irwin 2008 Toews, D. P. L. and D. E. Irwin. (2008). Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. Molecular Ecology 17 (11):2691-2705. Close on song; Mclachlin 1983 Mclachlin, R. A. (1983). Dispersion of the Western Winter Wren (Troglodytes troglodytes) in the coastal western hemlock forest at the University of British Columbia Research Forest in southwestern British Columbia. Phd Thesis, Univ. of British Columbia, Vancouver. Close , Van Horne and Bader 1990 Van Horne, B. and A. Bader. (1990). Diet of nestling Winter Wrens in relationship to food availability. Condor 92:413-420. Close , and Field and Reynolds 2011 Field, R. D. and J. D. Reynolds. (2011). Sea to sky: Impacts of residual salmon-derived nutrients on estuarine breeding bird communities. Proceedings of the Royal Society B-Biological Sciences 278 (1721):3081-3088. Close on food habits; Heath 1920 Heath, H. (1920). The nesting habits of the Alaska Wren. Condor 22:49-55. Close , Bent 1948b Bent, A. C. (1948). Life histories of North American nuthatches, wrens, thrashers, and their allies. United States National Museum Bulletin 195. Close , Mclachlin 1983 Mclachlin, R. A. (1983). Dispersion of the Western Winter Wren (Troglodytes troglodytes) in the coastal western hemlock forest at the University of British Columbia Research Forest in southwestern British Columbia. Phd Thesis, Univ. of British Columbia, Vancouver. Close , Waterhouse 1998 Waterhouse, F. L. (1998). Habitat of Winter Wrens in riparian and upland areas of coastal forests. Master's Thesis, Simon Fraser Univ., Vancouver, BC. Close , Willson and Gende 2000 Willson, M. F. and S. M. Gende. (2000). Nesting success of forest birds in southeast Alaska and adjacent Canada. Condor 102:314-325. Close , Waterhouse et al. 2002a Waterhouse, F. L., A. S. Harestad and P. K. Ott. (2002a). Use of small streams and forest gaps for breeding habitats by Winter Wrens in coastal British Columbia. Northwest Science 76 (4):335-346. Close , De Santo et al. 2003 and Evans Ogden et al. (in press) on breeding biology, behavior, and habitat use; and numerous community studies examining the effects of timber harvesting on Pacific Wrens, especially Rosenberg and Raphael 1986 Rosenberg, K. V. and M. G. Raphael. (1986). "Effects of forest fragmentation on vertebrates in Douglas-fir forests." In Wildlife 2000: modeling habitat relationships of terrestrial vertebrates., edited by J. Verner, M. L. Morrison and C. J. Ralph, 263-272. Madison: Univ. of Wisconsin Press. Close , Lehmkuhl et al. 1991 Lehmkuhl, J. F., L. F. Ruggiero and P. A. Hall. (1991). Landscape-scale patterns of forest fragmentation and wildlife richness and abundance in the southern Washington Cascade Range. Portland, OR: U.S. Dep. Agric. Close , Hejl and Paige 1994 Hejl, S. J. and L. C. Paige. (1994). "A preliminary assessment of birds in continuous and fragmented forests of western redcedar/western hemlock in northern Idaho." In Interior cedar-hemlock-white pine forests: ecology and management., edited by D. M. Baumgartner, J. E. Lotan and J. R. Tonn, 189-197. 1993. Washington State Univ., Pullman: Spokane, WA. Close , Mcgarigal and McComb 1995 Mcgarigal, K. and W. C. McComb. (1995). Relationship between landscape structure and breeding birds in the Oregon Coast Range. Ecological Monographs 65:235-260. Close , Hutto and Young 1999 Hutto, R. L. and J. S. Young. (1999). Habitat relationships of landbirds in the Northern Region. U.S. For. Serv. Close , Brand and George 2001 Brand, L. A. and T. L. George. (2001). Response of passerine birds to forest edge in coast redwood forest fragments. Auk 118 (3):678-686. Close , and McRae et al. 2008 McRae, B. H., N. H. Schumaker, R. B. McKane, R. T. Busing, A. M. Solomon and C. A. Burdick. (2008). A multi-model framework for simulating wildlife population response to land-use and climate change. Ecological Modelling 219 (1-2):77-91. Close .