Blue-winged Warbler Vermivora cyanoptera or near the ground. The female lays four or five eggs that are white with brown speckling, and raises a single brood. Diet Blue-Wings eat insects and spiders, particularly caterpillars, grasshoppers, and crickets. They forage in the upper half of trees and shrubs, often hanging upside down while probing for insects in curled leaves, buds, flowers, or on twig surfaces. Female (left) and Male (right) Blue-winged Warblers with nestlings — Photo: B. Henry/VIREO Identification (11–12 centimetres) The Blue-winged Warbler is easily overlooked skulking in thick undergrowth, despite its bright colour. Males are unmistakable — yellow above and below, grey wings with two white bars, and a black eye stripe. They sing a two-syllable insect-like “beeeeebuzzzzzz.” Females are duller, but otherwise similar. Management Guidelines Although not currently a species of concern in Ontario, significant declines have occurred across much of their range in the United States. Blue-winged Warblers benefit from management strategies that maintain early to mid-successional habitats, including prescribed burns in fire-dependent habitats. How to Find This species can be found in areas of dense shrubs along forest edges. Listen for its loud insect-like “bee-buzzzz” song or watch for its chickadee-like behaviour probing in leaves in the lower canopy. Conservation Status The Blue-winged Warbler breeds in open scrubby areas in southern Ontario and the eastern U.S. Its population in Ontario has increased over the last few decades due to a northeast expansion in breeding range, where it is replacing the very closelyrelated Golden-winged Warbler. However, across its entire North American breeding range, numbers have decreased 1.1 percent annually due to forest maturation and urban sprawl. Breeding Biology The breeding range of the Blue-winged Warbler has changed markedly over the last century. It breeds in early to mid-succession habitats, especially abandoned farmland and forest clearings, and at forest/field edges, often shaded by large trees. It breeds from late- May to end of June, seeking out openings with dense understorey. It builds a well concealed nest of grasses, bark and dead leaves on Did you know? • The Blue-winged Warbler hybridizes with the Golden-winged and typically displaces them in areas of territory overlap and hybridization, often within 20 years of initial contact. • Expansion of Blue-wings is linked to declines in populations of Golden-wings, since they are more of a habitat generalist and are genetically dominant. • As soon as nest construction begins, the female Blue-winged Warbler will sit on the nest every night even though it is incomplete and has no eggs in it yet. • Leaves can be positioned over nests to form a cap that conceals eggs and brooding females. 122 Bird Species Accounts

Golden-winged Warbler Vermivora chrysoptera and second growth forest with sapling regeneration, typically surrounded by mature forests. Nests are constructed on the ground or slightly above, often placed at the base of a plant or in a grass tussock. The female lays four to five whitish eggs with brownish speckling, and raises one brood per season. Diet Moths, including larvae and pupae, are the main food of the Golden-winged Warbler. It also eats spiders and various winged insects. It forages at various levels, often hanging upside down from branches, and probing curled leaves in search of prey. Management Guidelines The Golden-winged Warbler suffers from a loss of nesting habitat due to succession, urban sprawl, and large scale reforestation. Management that maintains early successional forest habitat is crucial for its survival. Because of the ephemeral nature of its habitat, it is important to have areas that are recently disturbed or burned at a local scale to maintain habitat for this early successional forest specialist. Male Golden-winged Warbler — Photo: Jeff Nadler Identification (13 centimetres) The Golden-winged Warbler is a small grey bird of open scrubby areas. Its wings and crown are marked with bright yellow patches. Both sexes have a white eyebrow and mustache. The male has a black mask and throat which is dark grey in females. Conservation Status The Golden-winged Warbler has generated a great deal of scientific and public interest over the last several decades as one of the fastest declining songbirds in North America. Declines stem from the loss of early successional scrub habitat, hybridization with the closely related Blue-winged Warbler in areas where the two species’ ranges overlap, and loss of habitat on its restricted wintering grounds in South America. At the same time, its breeding range has been expanding to the north where pastureland abandonment is common. In Canada, the species is listed as threatened. Breeding Biology The Golden-winged Warbler’s breeding range is concentrated in the northeastern United States, southern Ontario, and southern Manitoba, with scattered populations in southwestern Quebec and extreme southeast Saskatchewan. In Ontario, it breeds from mid- May to mid-July in early successional deciduous habitats such as forest edges, shrubby power-line corridors, abandoned farm fields, How to Find Search for the Goldenwinged Warbler in dense shrubby areas near forest edges. Make sure to listen for its descending buzzy call — “bee-buzzbuzz-buzz.” Did you know? Photo: Greg Lavaty • The Golden-winged and Blue-winged Warbler hybridize to produce viable offspring. The Blue-wing has a dominant genetic makeup, so Golden-wings effectively become genetically “swamped.” • In areas of contact, Golden-wings may be replaced by Blue-wings in less than 10 years. • Hybrids do not sing intermediate songs but sing either normal Blue-winged Warbler or Golden-winged Warbler songs. Some birds sing both. Occasionally pure-looking parental types sing the wrong song. • Adult Golden-winged Warblers that have nestlings will attempt to lure away nearby predators by repeatedly carrying food to a fake nest location. Bird Species Accounts 123