Bicolored Wren Campylorhynchus griseus Scientific name definitions

The Bicolored Wren is one of the largest members of the wren family. As is typical of the tropical members of the group, the Bicolored Wren exhibits strong geographic variation. The six subspecies vary in the saturation of black on the head, eye-line, back and wing coverts. The western subspecies in northern Colombia and northwestern Venezuela are the most striking, with the greatest amount of black in the plumage, and the more easterly subspecies becoming progressively more rufous. Typical of the genus, the Bicolored Wren is a cooperative breeder and builds a domed nest with a narrow side-entrance; this species also will regularly adopt and convert other domed nests built by species of other genera, such as Pitangus or Myiozetetes.

21–22 cm; 37–46·5 g. Nominate race has off-white supercilium contrasting with dark brown eyestripe; crown and nape dark chocolate-brown, back paler chocolate-brown; primaries and secondaries as back but with numerous darker bars; rectrices brownish-black with conspicuous white subterminal band on all but central pair, broadest on outer feathers; throat and entire underparts white; eye brown; bill black, grey base of lower mandible; legs slate-grey. Sexes similar. Juvenile has back greyer and less rufescent than adult, cap mottled grey-brown, underparts grey-white. Race <em>albicilius</em> is deeper rufous than nominate; bicolor is similar to previous, but less bright rufous on rump; minor is smaller, with blackish-brown nape and upper back; pallidus has back much more grey, less rufous, than nominate, with darker crown.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Scattered bushland, of varied nature. In Colombia, race <em>bicolor</em> occurs in arid thorn-scrub with cacti, but other races in quite humid areas. Absent from both completely forested areas and completely open areas. Sea-level to 2100 m in Colombia, to 1600 m in Venezuela.

Apparently sedentary.

Mostly invertebrates ; significant amounts of vegetable matter also taken, including berries, and reported as destructive to fruit such as mangoes. According to local Colombian tradition, enters hen-houses and predates eggs. Forages in trees and palms, also on ground .

Song a series of multiple loud gurgling notes, 2–5 per phrase, with harsh grating undertone, female song slightly different and invariably including a trill; marked geographical variation in song type, race albicilius in particular differing from e.g. minor; pair-members sing individually or in duet, or in choruses with three or more individuals singing simultaneously. Calls varied, mostly harsh and grating.

Jan–Mar and May–Aug in Venezuela. Co-operative breeder, although extent to which this occurs highly variable, in some populations majority of nests have one or more helpers, in others only 15%; helpers are blood-relatives (frequently brothers or sisters) of nesting pair. Nest a domed structure with small side entrance, made of grass and fibres , placed 3·5 m or more above ground and well concealed in tree or palm; old domed nest of other species, e.g. tyrannid (of genus Pitangus or Myiozetetes), or pendent one, e.g. of Rufous-fronted Thornbird (Phacellodomus rufifrons), also used. Eggs 3–5, buff or cinnamon, speckled with brown; incubation by female alone, period 17 days; chicks fed by both sexes, and by helpers when present, for c. 17 days in nest and up to 30 days after fledging. Nests with helpers up to three times more successful than those without, enhanced success due to better defence of nest.

Not globally threatened. Frequently common or abundant. Able to tolerate substantial modification of habitat, provided that sufficient bushes remain; for example, can co-exist with agricultural practices such as ranching.