Canada Warbler

(Cardellina canadensis)

Status: Special Concern (ESA 2009), Threatened (SARA 2010)

Table of Contents:

Species Identification
Diet
Habitat and Range
Biology and Behaviour
Similar Species
Threats/Reasons for Being Endangered
Conservation and Recovery Strategies
How You Can Help

A male Canada Warbler

Species Identification:

The Canada Warbler has a bright yellow chin and belly, with black-blue feathers on top if male, and light grey if female. Males have black feather streaks that create a checkerboard across their chest, and the female has the same pattern, but lighter in colour. Their bold white eye rings are a useful identification feature for both sexes. The Canada Warbler can usually be located by its loud, distinctive song that starts with a chirp, followed by a series of warbling notes that end in a higher pitch. The Canada Warbler keeps its plumage all year round.

Diet:

Canada Warblers catch insects off the ground or low in vegetation like shrubs either by snatching them from the air- which is called flycatching, or picking them off leaves and from crevices, which is called gleaning. Their diet consists of beetles, flies, caterpillars, spiders and mosquitoes.

A female Canada Warbler

Breeding, migrating, and wintering distribution of Canada Warbler (adapted from BirdLife International and NatureServe (2013), using data from Haché et al.(2014), and eBird (2014)). https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/recovery-strategies/warbler-2016.html#_03

Habitat and Range:

The Canada Warbler prefers wet forests with high amounts of low-growing vegetation for feeding, but they can thrive in a large range of forest types. They are commonly found in recovering forest stands following forest fires or human disturbances (generally 6 to 30 years after a disturbance). Over 80% of the global population breeds in Canada throughout the boreal forest region. The breeding range extends from northern British Columbia and all the way to the Maritimes, northeast coast of the US, Great Lakes region, and parts of the Appalachian Mountains. They overwinter in South America, with most populations concentrated in the northern Andes of Colombia, Venezuela, Ecuador, and Northern Peru.

The Canada Warbler breeds throughout most of Ontario, especially near the Southern Shield region, which includes the Land Between. Population declines are mainly due to loss of wet woodlands and road expansion into our boreal forests.

Biology and Behaviour:

Adults return from winter migration to their breeding ground from mid-May to mid-June. They generally choose one mate each year, and raise one brood of offspring. The female builds a cup-shaped nest out of leaves, grasses, ferns and bark on the ground or on stumps and logs, usually close to a stream. They lay 4-5 eggs which they incubate for about 12 days, and once hatched the mother will remain in the nest for another 10 days while the male collects food.

Similar Species:

The Kentucky Warbler is similar but has only half an eyering, greenish upperparts, and lacks the black chest markings.
Northern Parula has white wing bars and a white belly.
Kirtland’s Warbler has black streaking on its sides and flanks, and dark streaks on its back.

Threats/ Reasons for being at Risk:

1. Loss of forest habitat in breeding grounds: In the 1960s -1980s most wetland forests in southern Canada were drained and converted for agricultural production or urban development. Disturbance and loss of forest cover is also due to road expansion for oil production in the boreal forest region, especially in Alberta. Today, many wetlands and forests are still being lost due to urban expansion and development northward.

2. Loss of forest undergrowth: Forestry practices that prioritize commercial wood production reduces the amount of low vegetation and shrubs in a forest as they harvest wood. Overgrazing by ungulates (ie. White-tailed Deer) is also a problem in some areas with high deer populations since their main food sources are saplings, small shrubs, and low vegetation.

3. Loss of forest cover in the Northern Andes: This is occurring primarily in Colombia due to economic pressures. Over 90% of forests have been converted for agriculture and pastures, and deforestation for wood fuel.

4. Accidental collision with buildings and cars: Canada Warblers migrate at night, which increases their risk of colliding with buildings, cars, and other human infrastructures such as power lines and wind turbines.

Conservation and recovery strategies:

The main focus for the federal recovery strategy is to improve the knowledge gaps for this species through research projects. To better assist in population recovery, more information is needed about migratory patterns, habitat use, and the suspected threats to Canada Warblers and their prey. Other objectives include a policy review of window designs to help reduce collisions, and ensuring compliance with the Migratory Birds Convention Act and other Beneficial Management Practices (BMPs) for this species.

How can you help?

Leave wooded areas intact on your property and encourage low vegetation growth.
Ensure any wood, pulp and paper products you buy are sourced from forestry operations that enforce best management practices and sustainability.
Buy FairTrade, shade-grown coffee. Coffee that is certified as “bird friendly” is even better!
Make your windows visible to birds using decals or blinds, and close blinds or curtains at night so light does not escape.

Additional Resources:

FRI recommendations for forest management to preserve Canada Warbler breeding habitat.
Cornell Lab has an informative Canada Warbler species profile.
Nature Canada has a page on Canada Warblers.

Sources:

Bezener, A. 2000. Birds of Ontario.

Environment Canada. 2016. Recovery Strategy for the Canada Warbler (Cardellina canadensis) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. vii + 56 pp.