Golden-winged Warbler

(Vermivora chrysoptera)

Status: Threatened (COSEWIC 2006 & SARA 2007), Special Concern (Ontario 2008)

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 Golden-winged Warbler

Species Identification:

The Golden-winged Warbler is a small songbird of about 11 cm and weighs 10 grams. They are mostly grey with white underparts, and they have distinct yellow patches on their wings and forehead. Males have a black throat and eye patches, while females have the same markings in grey. Males sing a buzzy song with a long high note followed by shorter and lower notes. Both males and females will make a “tzip” sound to each other while courting.

Diet:

The Golden-winged Warbler’s diet consists mainly of moths and their larvae. They also eat other winged insects, caterpillars, and spiders. They are entirely insectivorous during breeding season, and little is known about their habits during migration. Golden-winged Warblers will use their sharp beaks to search rolled up leaves for hidden prey, and then hop along the branches of shrubs to inspect the leaves. They rarely will catch prey while in flight.

A female Golden-winged Warbler, photo by Andy Reago & Chrissy McClarren: https://flic.kr/p/L9mHWt

Map taken from Wildlife Species Canada: https://wildlife-species.canada.ca/species-risk-registry/virtual_sara/files/plans/Rs-GoldenWingedWarbler-v00-2016Aug05-Eng.pdf

Habitat and Range:

The Golden-winged Warbler’s breeding range within Canada extends from the edge of Saskatchewan to Manitoba, southern Ontario, and Quebec. There is another population within the Appalachian Mountains in the United States. Almost all of the Canadian population (>200,000 birds) is within Ontario. They mostly breed in the central and eastern regions of the province extending to the top of Georgian Bay to the north, and down to the St. Lawrence River in the south. An estimated 79% of the Ontario breeding population occurs within The Land Between. Their overwintering range extends through Central America from the south of Mexico to the northern parts of Venezuela, Colombia, and Ecuador.

A mapping project within The Land Between shows that the Golden-winged Warbler is associated with treed wetlands that are near mixed forest or cropland. Their breeding habitat is within specific forest mosaics in either upland or wetland areas. They need large amounts of forest cover (~75%), with a majority of deciduous trees. They thrive in early-successional forests and require sparse trees with an undercover of shrubs and herbs.

Biology and Behaviour:

The male Golden-winged Warbler returns to their breeding range in early May, one or two weeks before the female. They often return to the same location year after year, and breed in loose colonies of up to 10 pairs. Upon returning to their territories, the males will be extremely vocal and territorial for 3 to 4 weeks during breeding season in order to attract a mate. Once the warblers pair off, the female builds a nest of tree bark, grass, and leaves at the base of a shrub or directly on the ground. She lays 2-6 eggs, then incubates one clutch each season. Though the nests are somewhat hard to find, eggs are vulnerable to predation by a wide range of rodents, coyotes, raccoons, snakes, and corvids.

Similar Species:

The Golden-winged Warbler looks similar to the Black-capped Chickadee, but this bird lacks yellow patches. Hybrid individuals of the Blue-winged and Golden-winged Warblers are hard to differentiate. Hybrid “Brewster’s” and “Lawrence’s” warblers have yellow feathers covering much of their body, and black patches that do not extend as far as those on the Golden-winged Warbler.

Threats/ Reasons for being at Risk:

1. Competition and hybridization with the Blue-winged Warbler: Both warblers have similar life history strategies. The two species used to have separate ranges, but the Blue-winged Warbler has expanded north as more land became cleared for agriculture. The two warbler species now must compete for nesting resources, food, and territory, and in areas where the species’ territory overlaps the Golden-winged Warbler has been shown to have smaller clutch sizes. The Golden-winged x Blue-winged Warbler hybrid offspring, sometimes called “Brewster’s Warblers” or “Lawrence’s Warblers”, are found throughout most of the breeding range, especially in southern Quebec and Ontario. Hybridization is leading to the extirpation of Golden-winged Warblers in areas where the two warblers overlap, as new species emerge and also share the same resources.

2. Loss of a suitable forest habitat: This is mainly due to forest succession. They require a mix of new and old successional stages and shrubby patches, but the maturing forests in old farmlands in combination with fire suppression means that there are insufficient disturbances to provide open patches and young forests. Our forests are also being cleared or fragmented by urbanization and development, and the Golden-winged Warbler needs a large amount of undisturbed forest in order to survive.

3. Invasive species: Invasive species have been a huge issue throughout Canada. For the Golden-winged Warbler, Common and Glossy Buckthorn outcompete new hardwood saplings and herbs. Phragmites are also dominating wetland habitats, making it difficult for them to forage and find nesting material. Non-native earthworms can also change leaf litter and soil composition, facilitating further invasion by other non-native species. Nest parasitism by the brown-headed cowbird is also contributing to population declines to some extent.

5. Urban development: Golden-winged Warblers need a vast and uninterrupted breeding range, and urban development leads to either fragmentation or permanent removal their habitat. In The Land Between specifically, shoreline development is altering the treed wetland habitat in which the Golden-winged Warbler is most often found. This local threat could have substantial consequences for the Ontario population, since 79% of the breeding population lives here.

Conservation and recovery strategies:

The broader management strategy to recover Golden-winged Warbler populations includes identifying focal areas, and prioritizing the appropriate conservation and recovery of areas beyond the Blue-winged Warbler range. Since the Golden-winged Warbler is listed as Special Concern in Ontario, no direct efforts are being made by the government. Forest managers should follow the Ontario Ministry of Natural Resource’s updated Forest Management Guide for Conserving Biodiversity at the Stand and Site Scales. These regulations ban the construction of new roads or aggregate in or around wetlands that are known habitat for Golden-winged Warblers, and prohibits activities that would alter water levels. Managers of right-of-way corridors and old farmers fields should follow best management practices and create habitat whenever possible. Habitat creation activities should occur outside the breeding season (from end of August till early April). Depending on the state of the original site, activities may include mechanical treatment, described burn or grazing, planting desired tree species and/ or timber management. The end result should aim for a landscape with mostly deciduous trees covering three quarters of the area, and a heterogeneous understory of shrubs and herbs.

How can you help?

Control invasive species on your land (e.g. buckthorn, phragmites).
Support controlled burns and rotational management in your region.
Keep an eye out for Golden-winged Warblers during breeding season and help ensure there is no habitat manipulation from May to July.
Participate in local bird surveys and report sightings to the NHIC.
Promote habitat creation in right-of-way corridors, including patches of shrubs and grass.
Support research. There is still a lot that is unknown about this species, especially around their migration.
Buy shade-grown organic coffee to support best practices in overwintering territory.

Additional Resources:

Golden-winged Warbler working group (website)
Brochure: breeding habitat guidelines
Muskoka Watershed Council handout
Best Management Practices for the Great Lakes Region

Sources:

Cadman et al. 2007.

Confer, J.L., J.L. Larkin, and P.E. Allen. (2003). Effects of vegetation, interspecific competition, and brood parasitism on Golden winged Warbler (Vermivora chrysoptera) nesting success. The Auk. 120(1), 138-144.

COSEWIC 2006. COSEWIC assessment and status report on the Golden-winged Warbler Vermivora chrysoptera in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 30 pp. (www.sararegistry.gc.ca/status/status_e.cfm).

Environment and Climate Change Canada. 2016. Recovery Strategy for the Golden-winged Warbler (Vermivora chrysoptera) in Canada. Species at Risk Act Recovery Strategy Series. Environment and Climate Change Canada, Ottawa. vii + 59 pp

Golden-winged Warbler Working Group. 2013. Best Management Practices for Golden-winged Warbler Habitats in the Great Lakes Region. www.gwwa.org

OMNR. 2010. Forest Management Guide for Conserving Biodiversity at the Stand and Site Scales. Toronto: Queen’s Printer for Ontario. 211 pp.