{"id":6097,"date":"2024-10-11T11:00:00","date_gmt":"2024-10-11T11:00:00","guid":{"rendered":"https:\/\/wordpress.viu.ca\/biol325\/?p=6097"},"modified":"2024-10-25T18:09:24","modified_gmt":"2024-10-25T18:09:24","slug":"pacific-wren","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2024\/10\/11\/pacific-wren\/","title":{"rendered":"Pacific Wren"},"content":{"rendered":"\n

Pacific Wrens (Troglodytes pacificus<\/em>) are minute songbirds known for their remarkably loud and complex song, which echoes throughout the understory of the mature forests in which they live. With thin, narrow beaks, these little round birds search for insects inside crevices and hollows on the forest floor, which has earned them their generic name Troglodytes<\/em>, from the Ancient Greek word for “cave dweller”.<\/p>\n\n\n\n

\"Earthbound
Julio Mulero, 2018<\/a><\/figcaption><\/figure>\n\n\n\n

Description & Identification<\/h2>\n\n\n\n

Physical and Comparative Description <\/h4>\n\n\n\n

In general, Wrens can be identified by narrow bills, drab plumage, small body size, frequently upturned tails, and a magnificent, bubbling song. Of the four species of Wren known to occur on Vancouver Island, the Pacific Wren is the smallest and most rotund, weighing between 8-12 g and with a wingspan of 12-16 cm (Pacific Wren Identification, n.d.). It is virtually indistinguishable from the closely related Winter Wren (Troglodytes hiemalis<\/em>), although a trained ear may be able to differentiate them by song (Toews & Irwin, 2020). Fortunately, the Winter Wren does not occur in southern British Columbia (Winter Wren Range Map, n.d.).<\/p>\n\n\n\n

\n
\"\"<\/a>
Jerry McFetridge, 2020<\/a><\/figcaption><\/figure>\n\n\n\n
\"\"<\/a>
Markus Weilmeier, 2022<\/a><\/figcaption><\/figure>\n<\/figure>\n\n\n\n

The Pacific Wren is a dark, uniform brown colour across its entire body, with a short tail and heavily barred flanks. Only the supercilium, chin and throat are slightly<\/em> paler; the supercilium is more conspicuous than that of a House Wren, but much less so than that of a Marsh or Bewick’s Wren. Each of these three species can be uniquely differentiated from the Pacific Wren by comparing characters such as size, plumage, and habitat.<\/p>\n\n\n\n

\n
\"\"<\/a>
a) House Wren, Troglodytes aedon<\/em><\/figcaption><\/figure>\n\n\n\n
\"\"
b) Bewick’s Wren, Thryomanes bewickii<\/em><\/figcaption><\/figure>\n\n\n\n
\"\"<\/a>
c) Marsh Wren, Cistothorus palustris<\/em><\/figcaption><\/figure>\n<\/figure>\n\n\n\n

a)<\/strong> Compared to the Pacific Wren, the House Wren (Troglodytes aedon<\/em>) will be larger and paler (particularly on the underside), with a longer tail and a grayer throat and breast (Johnson, 2020). The House Wren is the least common of our four local Wrens, and is generally somewhat tolerant of urbanization (Lumpkin & Pearson, 2013; Newhouse et al., 2008). Photo: Mitchell Goldfarb, 2021<\/a><\/p>\n\n\n\n

b)<\/strong> Bewick’s Wren (Thryomanes bewickii<\/em>) is noticeably larger than the Pacific Wren, with a pale grey underside contrasting with brown upperparts. The tail is long and barred, with white speckling on the distal tips, though it is best distinguished by a very distinctive white supercilium (Kennedy & White, 2020). Bewick’s Wrens are more commonly encountered and prefer drier, more open woodland compared to the Pacific Wren (American Ornithologist’s Union, 1983). Photo: Gavin Aquila, 2024<\/a>.<\/p>\n\n\n\n

c)<\/strong> The Marsh Wren (Cistothorus palustris<\/em>) is approximately the size of a House Wren, with a cinnamon-coloured rump and scapulars and a triangular black-and-white blotch on it’s back. Occasionally it has faint ventral barring, but generally the underside is a pale white with buffy flanks. Like the Bewick’s Wren, it has a distinct white supercilium, however the Marsh Wren also possesses a black crown (Kroodsma & Verner, 2020). Unlike the Pacific Wren, the Marsh Wren is found predominantly in wetland areas where it nests amongst bulrushes and cattails (Leonard & Picman, 1987). Photo: Will Cihula, 2024<\/a>.<\/p>\n\n\n\n

Vocalization<\/h4>\n\n\n\n

Gram-for-gram, there is perhaps no other bird in British Columbia that is able to produce a song of such length and complexity as the Pacific Wren, besides its sister species, the Winter Wren. Their songs are highly complex and can be extremely variable in length, but usually range between 5 and 10 seconds of trilling, bubbling notes that climb and then tumble repeatedly in tone (Pacific Wren Sounds, n.d.):<\/p>\n\n\n\n

Steve Hampton, 2018<\/a><\/figcaption><\/figure>\n\n\n\n

Life History<\/h2>\n\n\n\n

Habitat & Distribution<\/h4>\n\n\n\n

In the breeding season (April – July), the Pacific Wren is most at home near flowing water in the riparian zone of old-growth or mature second-growth forests, where fallen logs are abundant (Waterhouse, 1998). Breeding presence is strongly correlated to salmonid returns in local streams (Field & Reynolds, 2011), where it is thought that the nutrient deposition from one autumn would contribute to increased invertebrate abundance the following summer (Christie & Reimchen, 2008). Mature stands of forest are preferred because they tend to have abundant deadwood, which is important for foraging for arthropods; the greatest abundance of Pacific Wrens are generally found in those stands that exhibit the most structural complexity, not simply the oldest (Waterhouse, 1998). Nonbreeding birds tend to remain associated with dense woody vegetation, but do not restrict themselves to mature forests as heavily (Toews & Irwin, 2020).<\/p>\n\n\n\n

\"\"
T. pacificus<\/span> is generally restricted to the Pacific coast of North America. Its close relative, T. hiemalis<\/span>, is much more widespread across the continent, and they were originally considered to be the same species <\/em>(Pacific Wren Range Map, n.d.).<\/figcaption><\/figure>\n\n\n\n

Foraging & Locomotion <\/h4>\n\n\n\n

The Pacific Wren is an erratic, nervous forager that has been frequently referred to as “mouse-like” in habit, as it diligently searches by “skipping” (Grinnell & Storer, 1924) and hopping through root tangles, hollows and stream banks for small arthropods to glean from the ground or from low vegetation (Bent, 1948). It has a particular taste for spiders, caterpillars, and beetles (Van Horne & Bader, 1990).<\/p>\n\n\n\n

\n