Bay-breasted Warbler vs Chestnut-sided Warbler

In short

The Bay-breasted Warbler and Chestnut-sided Warbler can be distinguished by their plumage and habitat preferences. The Bay-breasted Warbler has a more uniform appearance with distinct bay-colored flanks, while the Chestnut-sided Warbler is notable for its bold chestnut sides and contrasting yellow crown. Both species are insectivorous but have different breeding habitats.

Identification tips

• Breeding plumage: Look for the bay-colored flanks in Bay-breasted Warblers and the chestnut sides with a yellow crown in Chestnut-sided Warblers.
• Nonbreeding plumage: Bay-breasted Warblers can resemble Blackpoll Warblers; focus on subtle plumage differences.
• Behavior: Note the tail-cocking behavior of the Chestnut-sided Warbler.
• Habitat: Consider the habitat; Bay-breasted Warblers prefer coniferous forests, while Chestnut-sided Warblers are found in deciduous areas.

Size

Both species are similar in size, typical of small warblers.

Plumage

In breeding plumage, the Bay-breasted Warbler has a chestnut crown and flanks with a buffy underbelly, while the Chestnut-sided Warbler features bold chestnut sides, a yellow crown, and a white underbelly. Nonbreeding Bay-breasted Warblers can resemble Blackpoll Warblers, making them difficult to distinguish.

Behaviour

Both species are active foragers, but the Chestnut-sided Warbler often forages with its tail cocked, which can be a helpful behavioral cue.

Habitat

The Bay-breasted Warbler breeds in boreal coniferous forests, primarily in northern spruce forests, while the Chestnut-sided Warbler prefers deciduous and mixed woodlands with dense undergrowth.

Voice

The Chestnut-sided Warbler's song is often described as 'please, please, pleased to meet you,' which is distinct from the Bay-breasted Warbler's less well-documented song.