Head to head
Willow Flycatcher vs Alder Flycatcher
A willow flycatcher and an alder flycatcher look so alike that the two were treated as a single species for decades, and even now, appearance offers almost no reliable way to separate them in the field.
| Willow Flycatcher | Alder Flycatcher | |
|---|---|---|
| Scientific name | Empidonax traillii | Empidonax alnorum |
| Song | Sharp, buzzy "fitz-bew" | Burry, two-noted "free-beer" |
| Typical breeding range | Slightly farther south, willow thickets | Slightly farther north, boreal alder bogs |
| Visual identification | Nearly impossible without song | Nearly impossible without song |
| Taxonomic history | Split from alder flycatcher in the 1970s | Split from willow flycatcher in the 1970s |
| Subspecies conservation concern | Southwestern subspecies federally endangered | None comparable |
| Diet | Flying insects, some spiders | Flying insects, some spiders |
| Conservation status | Least Concern (species overall) | Least Concern |
Willow Flycatcher vs Alder Flycatcher: common questions
How can you actually tell a willow flycatcher from an alder flycatcher?
Song is by far the most reliable method, since the willow flycatcher sings a sharp, buzzy "fitz-bew" while the alder flycatcher produces a burry, two-noted call closer to "free-beer" — the two species look close to identical, and even experienced birders generally rely on voice rather than appearance to separate them confidently.
Why were these two treated as one species for so long?
Their appearance is close enough that early ornithologists saw no reason to split them, and it wasn't until researchers in the 1970s confirmed through genetic and vocal study that the two songs never overlap and the birds don't interbreed that a formal split into two separate species was justified.
Which of these two flycatchers is more at risk?
Neither species is broadly threatened, but the southwestern subspecies of the willow flycatcher is federally listed as endangered due to severe loss of the dense riparian willow habitat it depends on, a conservation concern the alder flycatcher does not carry to the same degree.