Canada warbler (Wilsonia canadensis)

KingdomAnimalia
PhylumChordata
ClassAves
OrderPasseriformes
FamilyParulidae
GenusWilsonia (1)
SizeLength: 13 cm (2) (3)
Wingspan: 20 cm (3)
Weight8 - 15 g (3)

The Canada warbler is classified as Least Concern (LC) on the IUCN Red List (1).

Frequently nicknamed the ‘necklaced warbler’ due to the distinguishing pattern of black spots across its yellow breast (4), the Canada warbler (Wilsonia canadensis) is a small, distinctive bird with brightly coloured plumage. It is also sometimes referred to as the ‘Canadian fly-catcher’ or the ‘Canadian fly-catching warbler’ because of its characteristic habit of actively foraging for flies on the ground (4) (5).

The Canada warbler has grey upperparts, white undertail coverts, and a bright yellow throat, breast and belly. The breast has a ‘necklace’ of streaks which vary in colour from black to grey. The width and darkness of the necklace varies depending on the age of the individual and whether it is male or female (2). This species is also noted for its characteristic yellow eyebrows and white eye rings, which form ‘spectacles’ around the eyes (2) (5) and are said to make this distinctive bird look somewhat ‘surprised’ (5). 

The adult male Canada warbler has extensive black colouration on the crown and face, with a bold, black necklace, which turn greyer in the autumn. The adult female is duller than the male, with very little black on the face or crown and dusky necklace streaks (2) (5). The juvenile is generally duller than the adult in appearance (6), being brownish on the head and upperparts and buff on the underparts (2).

The distinctive song of the Canada warbler is clear, loud and extremely variable. It consists of one ‘tchip’ or ‘chip’ note (3) (7), preceeded by a rapid, explosive series of short notes and concluded with a three-note phrase, the last note of which is loud and rises in pitch (7). A ‘chyup’ or ‘plip’ call is also given by both the male and the female (3) (7), and a loud, sharp ‘check’ or ‘chip’ is given in alarm (7).

The Canada warbler is found throughout the Americas. As its name suggests, around 80 percent of the Canada warbler’s breeding grounds are in Canada (6), although this species also breeds across the eastern and central United States (8) (9).

The wintering grounds of the Canada warbler are found mainly in northern South America (4).

In the breeding season, the Canada warbler occurs in the dense understory of cool, moist forests, where it is often found along streams or in other areas near water (4) (8) (10). Although generally found at elevations above 300 metres (4) (8) (10), the Canada warbler may also inhabit cool and wet areas at lower elevations (10).

The Canada warbler prefers mature deciduous or mixed deciduous-coniferous forest where small gaps in the canopy allow shrub layers to develop (11). The shrubby undergrowth provides this species with plenty of cover in which to hide (10).

The Canada warbler typically winters in wet or moist, densely-vegetated areas in a variety of tropical woodlands (3).

The Canada warbler is a social bird, typically living in flocks (3) (4). It usually arrives at its breeding grounds in May (8) (11), although the timing of breeding varies with location. In Pennsylvania, the majority of nests with eggs have been found between late May and mid-June (8), while in British Columbia, the Canada warbler has been recorded breeding from early June through to late July (11). Individuals may return to the same breeding grounds each year (4).

This species nests in forest and shrubby areas, often alongside power lines and roads (11). The well-concealed nest is typically a rather bulky structure built close to the ground, usually among the roots of a fallen tree, in a cavity in the ground, or in moist thickets, moss hummocks, dense ferns, or anywhere with deep litter and dense saplings (4) (8) (11).

The Canada warbler produces a clutch of four or five eggs, with only a single brood per season (3). The eggs are slightly glossy with a buff or creamy-white appearance, and are speckled with dots of varying tints and shades around the larger end (7). The female lays one egg per day during the laying period, with incubation beginning after the final egg is laid and lasting for 10 to 12 days (4) (6). Once hatched, the young chicks will leave the nest after seven to ten days (4) (6), and may live for up to eight years (3).The nests of the Canada warbler are frequently subject to brood parasitism by the brown-headed cowbird (Molothrus ater) (7).

The Canada warbler feeds on a variety of insects and spiders, which are plucked from foliage or from the ground. It will often wait for insects such as a crane fly to fly past, before pursuing it in flight (3) (4). This species has been observed feeding from the branches of trees, up to four metres above the ground (11).

Breeding Bird Survey data from Canada and the United States has indicated that the population of the Canada warbler has declined in parts of its range (8).

These declines are likely to be due to forest succession, as well as the loss and degradation of forested wetlands, which are being drained for urban development and agriculture (3) (6). Timber harvesting has led to the creation of more forest edges, which are providing greater opportunities for the brown-headed cowbird to parasitise the nests of the Canada warbler (4).

Deforestation of the Canada warbler’s wintering grounds is also a major threat (4), with around 95 percent of primary mountain forests in these areas cleared for agricultural use since the 1970s (6).

In the U.S., the Canada warbler population is generally considered to be secure. However, it is considered ‘Critically Imperiled’ or ‘Imperiled’ in Illinois, Indiana and Ohio (6). This species is also considered to be a species of high conservation concern by the ‘Partners in Flight North American Landbird Conservation Plan’ and the Northeast Endangered Species and Wildlife Diversity Technical Committee (12).

In Canada in particular, as much as 85 percent of the Canada warbler population may have disappeared since 1968, prompting COSEWIC to list the Canada warbler as a threatened species. Adults, nests and eggs of the Canada warbler are protected in Canada under the Migratory Birds Convention Act of 1994 (6).

This species would also benefit from the maintenance and protection of suitable habitat (6).

Find out more about the Canada warbler:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (August, 2011)
    http://www.iucnredlist.org/
  2. Dunn, J. and Garrett, K. (1997) A Field Guide to Warblers of North America. Houghton-Mifflin, Boston.
  3. Vuilleumier, F. (2009) Birds of North America: Western Region. Dorling Kindersley, New York.
  4. Reitsma,L., Goodnow, M., Hallworth, M.T., and Conway, C.J. (2010) Canada warbler (Wilsonia canadensis). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
    http://bna.birds.cornell.edu/bna/species/421.
  5. Earley, C.G. (2003) Warblers of the Great Lakes Region and Eastern North America. Firefly Books Ltd., Buffalo, New York.
  6. Savignac, C. (2008) COSEWIC Assessment and Status Report on the Canada Warbler in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa, Canada.
  7. Cornell Lab of Ornithology: Birds in Forested Landscapes - Canada warbler, Wilsonia canadensis (August, 2011)
    http://www.birds.cornell.edu/bfl/speciesaccts/canwar.html
  8. McWilliams, G.M. and Brauning, D.W. (2000) The Birds of Pennsylvania. Cornell University Press, Ithaca, New York.
  9. BirdLife International (August, 2011)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=9152
  10. Bonney Jr, R.E. (1988) Canada warbler. In: Andrle, R.F., Carroll, J.R., Federation of New York State Bird Clubs, New York (State) Deptartment of Environmental Conservation and Cornell University Laboratory of Ornithology (Eds.) The Atlas of Breeding Birds in New York State. Cornell University Press, Ithaca, New York.
  11. Campbell, R.W. (2001) Canada warbler. In: Canadian Wildlife Service, The British Columbia Ministry of Environment, Lands and Parks, and the Royal British Columbia Museum (Eds.) The Birds of British Columbia. Volume 4 – Passerines: Wood-Warblers through Old World Sparrows. UBC Press, Vancouver, Canada.
  12. Lambert, D. (2006) VINS releases report on Canada warbler habitat management. The All-Bird Bulletin, March, 2006: 3.