Hutton’s Vireo is reasonably distinct from other vireo species in B.C. and is easily distinguished from the most similar member of this group, the Cassin’s Vireo, by its smaller size, lack of bold white ‘spectacles’ on the face (Hutton’s Vireo has much duller, olive-tinged ‘spectacles’ that are broken above the eye) and overall duller and greener plumage, especially on the throat and underparts. Cassin’s Vireo has a whiter throat and underparts and is often tinged with grey on the head.
Hutton’s Vireo is very similar to the Ruby-crowned Kinglet, and this similarity likely accounts for occasional reports of Hutton’s Vireo in south-central B.C. outside of the expected range of the species. Differences in structure and behaviour, although subtle and requiring experience with both species to be valuable, are often helpful in differentiating these two species before the minor differences in plumage can be assessed. Hutton’s Vireo is a slightly (but noticeably) larger and bulkier species and has a distinctly thicker bill than Ruby-crowned Kinglet (which has a very fine, sharp bill). Hutton’s Vireo moves and forages in typical vireo fashion, moving relatively slowly and deliberately among the foliage and branches, whereas Ruby-crowned Kinglet is much more active, regularly flitting among the outer twigs and foliage and often hovering momentarily at branch tips in search of insects (this behaviour is only occasionally shown by Hutton’s Vireo). The most important plumage characteristic to note when separating these two species is the presence of a thick black bar on the wing of Ruby-crowned Kinglet. This bar is along the base of the secondaries and immediately below the lower of the two white wing bars. Hutton’s Vireo, in contrast, shows no such black bar and has only the two whitish wing bars. An additional field mark of Hutton’s Vireo is the more noticeable pale lores which, when combined with the pale eye-ring, give the bird the impression of having ‘spectacles.’ Ruby-crowned Kinglet has duller, greener lores and a brighter, whiter eye-ring so that it does not typically show the suggestion of ‘spectacles.’
| The song of the male is a variable, monotonous series of burry, nasal, one- or two-note calls that are often repeated at a rate of ~1 phrase per second for a period of up to 10 minutes. One commonly-heard variation of this song include a series of two-part notes with the second note higher-pitched: zu-weep...zu-weep....zu-weep…zu-weep…zu-weep… Another commonly-heard variation of this song is a series of descending, slurred notes: zweeer…zweeer....zweeer...zweeer…zweeer… Occasionally the male sings a monotonous series of flat, single-syllable phrases: chew…chew…chew…chew…chew… The most frequently produced call, especially during the winter, is a whinnying, chattering rheeee-he-he-he-he-he with a distinctive laughter-like quality; in some situations, only the raspy, ascending rheeeee portion of this call is given. Also gives a short, dry pik or chit and a high, harsh, mewing sshhhhrrii shhhri shhr shhr.Source: Davis (1995); Sibley (2000) |
Courtship
Courtship and pair formation occurs very early in the year, often as early as February or March. Some pair bonds may be retained throughout the year, as evidenced by observations of apparent pairs at all seasons. Courtship in this species primarily involves song, during which time the male sings for prolonged periods from an unexposed perch within the canopy. The male often moves about the branches while singing, sometimes even foraging between phrases. The female solicits copulation by crouching on a branch and fluttering her wings. Later in the season, the male sometimes sings from the nest while incubating the eggs.
Nest
Nest construction begins early, with some pairs beginning in late February or early March concurrent with the start of courtship. Both sexes participate in the construction of the nest over a period of 3-14 days (longer during prolonged periods of rain). The nest is usually placed near the end of a horizontal branch, where it is suspended from a fork in the branch and is usually well-hidden by overhanging foliage. Nest heights range from (1) 3-12 (15) m. The nest itself is a deep, rounded or somewhat globular hanging cup 7.6-8.3 cm wide and ~7 cm deep. It is composed of a wide variety of materials such as fine grasses, moss, lichens, small leaves, plant down, moth and spider cocoons, spider silk, feathers, and shreds of bark; moss is the most important construction material for nests in B.C. It is generally lined with fine grasses as well as smaller amounts of hair, feathers, and fine shreds of bark.
Eggs
A clutch of (1) 3-4 (5) eggs is laid within several days of the completion of the nest, usually in early spring (mid-March through April), and hatches 14-16 days later. Both sexes incubate the eggs. This species appears to be double-brooded, and presumed second clutches in B.C. have been recorded from May through June. The smooth, moderately glossy eggs are white and very sparsely marked with a few brown or reddish-brown specks or spots at the larger end (occasionally unmarked). The Hutton’s Vireo is an infrequent host for Brown-headed Cowbird parasitism, and several instances of such parasitism have been noted in B.C.
Young
The nestlings are altricial and naked upon hatching, with flesh-coloured or pinkish skin, but quickly develop pale yellowish-white to pinkish-white or very pale grey down. Both parents tend to the young throughout the nestling period, including brooding. The young leave the nest at 14-17 days of age and are subsequently tended by both adults for up to 3 weeks before becoming independent. Nestlings and dependent young are present in B.C. between early April and late July.
Source: Baicich and Harrison (1997); Campbell et al. (1997); Davis (2005)
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Most foraging activity takes place in the mid to upper canopy of coniferous or, less frequently, deciduous trees, often in the outer portions of the branches but generally not fully exposed. It sometimes descends to lower levels, occasionally moving into understory vegetation or even shrubby areas adjacent to mature trees. This species primarily consumes invertebrate prey, particularly insects and their larvae, which it gleans from the surfaces of branches, bark, leaves, flowers, and fruits. It sometimes hovers momentarily to glean prey or pursues aerial prey during short flights. Many prey items are captured by flying rapidly towards a branch or other surface and snatching the prey, then returning to a perch to consume it. Small berries (elderberries, etc.) are occasionally consumed when they are available, and this species has been known to drink sap oozing from holes created by the Red-breasted Sapsucker. Outside of the breeding season, the Hutton’s Vireo commonly travels with mixed-species feeding assemblages alongside chickadees, kinglets, nuthatches, and Brown Creeper. It is difficult to detect in these flocks, however, due to its quiet and retiring nature and tendency to occur as only one or two individuals per flock.
Source: Davis (1995)
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