Description:

This small warbler appears at a glance to be all yellow – hence its common name. It is a common summer breeding visitor all across Canada and US, except the very far north (beyond the tree line) and the southern States. In the Vancouver area, it is one of the most commonly seen warblers, arriving about May and departing in September.

It may be found in a variety of locations, such as gardens, parks, alongside lakes and streams, and especially in alder or willow thickets, preferring moist habitats.

Identification:

General: Characteristics are typical of a warbler such as the small size and thin short bill, and continual foraging among leaves for insects and grubs. It is usually unmistakable – the only overall bright yellow bird, and the only one with diagnostic yellow patches in the tail in any plumage. Its length is about 12.5 cm; weight 9.5g.

Adult Male: Upperparts mostly yellowish olive-green, becoming more yellow or yellow-orange on crown. Face and under parts rich yellow, with the sides, breast and flanks streaked with chestnut-red. Wings are darker yellow-brown with yellow edging. The short tail has yellow patches on inner webs. The bill is black and stouter than most warblers.

Adult Female: This is similar to the adult male, but is duller and slightly more greenish above and paler yellow below. Usually, there is much less bold or no chestnut streaking on the breast, sides and flanks.

Juvenile (first autumn): Generally similar to adult female, but much more dull overall, and less obviously yellow.

Similar species: In the Pacific region it is only likely that the female or juvenile might be confused with the slightly smaller female Wilson’s Warbler, but the latter does not have the diagnostic yellow inner webs in the tail.

Behaviour: Forages in thickets and undergrowth for insects and grubs, so it is often observed near eye level. Easily recognized by its song which is sweet and high, with clear notes, sounding like swee swee swee ti ti ti swee.

Habitat: Common in willow and alder thickets in moist areas such as bogs, stream sides, and lake edges. Also found in gardens and parks.

Information:

The Yellow Warbler is classed with the other Wood Warblers, all small active birds with short, pointed bills. The nest is usually found as a neat cup in a willow bush, fastened to a fork in a branch just a few feet off the ground. Eggs, usually 4-5, are white or bluish white, spotted mostly around the large end in brown or purplish grey. Incubation by the female is about 11 days. Yellow Warblers winter from Mexico and the Bahamas south to Peru and Brazil. Interestingly, Yellow Warblers have populated the Galapagos Islands as residents.

Conservation Status:

A widespread and abundant warbler but little is known about continent wide population trends. Although listed as LC (Least Concern) the species is vulnerable in western North America where its preferred riparian habitats are affected by intense grazing and habitat loss and degradation due to development.