I can’t say for sure if I have ever seen a yellow warbler. I know that because I have added question marks.
In 2006 I conducted a survey from readers. Only one person saw a yellow warbler. By May their song is heard across North America, up to the far north. They are highly detectable vocally and visually. My Mom used to tell us she saw a ‘wild canary’, as yellow warblers are erroneously called by some.
Status: occasional migrant and breeder from May to August. ID: This is an all yellow bird. The upperparts are yellow-green. The dark eye stands out as do distinctive reddish streaks on the breast of the male. Females are greener than males, with no visible streaks. Size: 13cm/5”. Lifespan: up to 9 years. Habitat: shrubby habitat, preferably near water. Twenty acres of territory is required. They might be the only warbler known to nest in a garden.
Feeding: hops from branch to branch, gleaning insects, caterpillars, beetles, aphids and cankerworms. Two thirds of their diet. Good news to everyone who cares about trees. Sometimes hovers midair. In late summer will eat berries.
Voice: Listen for its clear, whistled, cheery song “see see see, ti ti see” or “sweet sweet I’m so sweet”. Sings throughout the day, unlike other warblers. Nesting: One brood. Compact, deep cup of grass, weeds, shredded material in vertical fork of deciduous tree or shrub. Lined with down and fur. Builds on top of a nest containing Brown Cowbird eggs, building up to six stories. Prefers willows, alders, wild roses and grapes. In flight: dark flight feathers with yellow edges. Yellow wing bars. Migration: central and northern South America. Status: special concern in Ontario.
Resources: Birds of Ontario, Audubon, Backyard Bird-lovers guide, DK and Alberta Guide Books and Cornell Lab.