Separated from other species of wrens with relative ease given its tiny size, very short tail, wholly dark colouration, and habitat preferences. May occasionally be confused with House Wren, but that species is larger, longer-tailed, and paler brown (often somewhat grey-tinged).
Pacific Wren is morphologically very similar to the Winter Wren of northeastern B.C., with which it was formerly lumped, and identification of non-singing or non-calling individuals (particularly out of range) would be considered very challenging, particularly given the variation within each species. Pacific Wren averages overall darker and less distinctly patterned than Winter Wren, which is slightly paler, browner, less rufescent, and more distinctly patterned. The differences are particularty noticeable on the face and throat, with Pacific Wren averaging slightly darker and more rufescent on the throat and breast, with a darker, rusty-tinged, less well-defined buffy-brown supercilium. Until the morphological differences between these two recently-recognized species are more thoroughly investigated, however, they are best distinguished by their distinctive songs and call notes.
| The Pacific Wren is renowned for its spectacular song, which is given frequently by the male during the breeding season. The song is a spectacular, long (up to 10 seconds), loud, complex, tumbling or cascading series of rapidly-delivered (up to 36 notes per second) ringing buzzes and hard trills; the song is longer, more rapid, more variable, and considerably more complex than the song of the boreal/eastern Winter Wren. The most common call note is a sharp timp or chat, often doubled, that is reminiscent of (but slightly sharper than) the call note of the Wilson’s Warbler; the analagous call of the Winter Wren is a hard jip that is similar in tone to the Song Sparrow and very different in quality from Pacific Wren. Also gives a rapid series of high-pitched staccato notes when agitated. Source: Sibley (2000); Hejl et al. (2002) |
Courtship
The female is attracted to the male’s territory early in the breeding season by the male’s continuous singing. As the female enters the male’s territory, the male moves very close to the female (usually within 1 m) and continues to sing, although this singing is typically softer and more subdued than the territorial singing. This close proximity singing is also often accompanied by displays such as wing fluttering and tail cocking. The male then leads the female around the territory, displaying each nest within the territory to the female (commonly perching at the entrance of each nest and singing softly while the female perches nearby). The female then enters each nest, sometimes accompanied by the male, until one of the nests is chosen and copulation occurs. Multiple females may occupy different nests within a single male’s territory.
Nest
Multiple nests are built throughout the breeding season (early spring to mid-summer), with peak nest building activity in May and June. Although the bulk of nest building is done by the male, the female always lines the nest prior to egg laying. The well-concealed nests are placed in either existing cavities or hollows (e.g., woodpecker holes, beneath loose bark, in natural tree hollows, under overhanging banks, etc.) or placed on free-standing surfaces or structures such as logs, root wads, brush piles, and buildings; nests are rarely built in shrubs or on exposed tree branches. Most nests are built on or near the ground, usually within 2 m of the ground (although rarely as high as 7 m). The nest is a stout, domed or globular structure 7-14 cm across with an entrance hole on the side that is 1-3 cm wide. It is composed primarily of of moss, twigs, grass, and leaves and has a lining of feathers, hair, plant fibres, rootlets, needles, and strips of bark.
Eggs
A single clutch of (1) 5-7 (9) eggs is laid between late March and June and is incubated by the female for 14-17 days before hatching. Although double-brooding has not been confirmed for this species (although it is suspected in B.C.), different females within a male’s territory breed at slightly different times and, thus, eggs may be found within a given male’s territory over a prolonged period during the breeding season. The smooth, glossy eggs are whitish, usually with small reddish-brown or pale brown speckles and spots that are distributed somewhat more heavily towards the larger end of the egg. Eggs are present in B.C. between late March and late August, although most occur between April and June; later clutches generally represent replacement clutches or, perhaps in some instances, second broods (e.g., on the Queen Charlotte Islands). This species is not known to suffer from Brown-headed Cowbird nest parasitism.
Young
The nestlings are fully altricial and downy at hatching, with flesh-pink skin and short, sparse dark grey down on the head and back; the gape is bright yellow and the gape flanges are pale yellow. The young remain in the nest for 15-20 days before fledging, during which time they are tended by both parents (although the male does less feeding than the female and does no brooding). After fledging, the young remain with the parents for 1-4 weeks and are fed by both parents early in the period. The male commonly has multiple females breeding within his territory and the young from these broods fledge at intervals. This allows the male to tend to only one or two broods at any given time. Nestlings and dependent fledglings have been recorded in B.C. between early April and mid-September, although most occur between May and July.
Source: Baicich and Harrison (1997); Campbell et al. (1997); Hejl et al. (2002)
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The Pacific Wren feeds entirely on insects, spiders, and other small invertebrates (snails, millipedes, amphipods, mites, etc.) that it captures while searching continuously and methodically on or near the ground in dense vegetation. It spends a considerable amount of time exploring the crevices and microhabitats associated with fallen branches, tree trunks, and decaying logs, and sometimes ventures to the edges of creeks and streams in search of aquatic and semi-aquatic prey (occasionally even submerging the head to capture prey). Sometimes forages in more open habitats, although generally within a short distance of dense cover. Prey is typically gleaned from vegetation or other surfaces or is captured while probing cracks and crevices.
Source: Hejl et al. (2002)
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