Acadian Flycatcher vs Willow Flycatcher

In short

The Acadian Flycatcher and Willow Flycatcher are both small, greenish Empidonax flycatchers, making them challenging to distinguish. The Acadian Flycatcher has longer primaries and a larger bill, while the Willow Flycatcher is best identified by its vocalizations. Habitat preferences also provide clues, with Acadian favoring mature forests and Willow preferring shrubby areas near water.

Identification tips

• Listen for vocalizations: Acadian's explosive song vs. Willow's "fitz-bew."
• Check habitat: Acadian in mature forests, Willow in shrubby, wet areas.
• Look at structure: Acadian has longer primaries and larger bill.
• Observe behavior: Both are aerial foragers, but habitat context helps.

Size

The Acadian Flycatcher has longer primaries and a larger bill compared to the Willow Flycatcher.

Plumage

Both species have similar greenish upperparts and pale underparts, making plumage a less reliable differentiator.

Behaviour

Both are primarily aerial foragers, but the Acadian Flycatcher is more often associated with mature forest environments.

Habitat

Acadian Flycatchers are typically found in mature deciduous forests, often near water, while Willow Flycatchers prefer shrubby areas along river corridors.

Voice

The Acadian Flycatcher has a distinctive explosive song, while the Willow Flycatcher's song is a key identifier, often described as a harsh "fitz-bew."