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| From top left clockwise: Yellow-bellied, Willow, Least, Cordilleran, Pacific-slope, Alder, Acadian, Hammond's, Gray, Dusky The Buff-breasted Flycatcher isn't included due to the fact that it's different from the other Empidonax species. |
This is my 3rd blog update, and it's about some of the most confusing species in the United States: Empidonax flycatchers. These ten species are olive-colored birds that are fond of forests and deep, wooded areas. They are all very similar, but they have slight differences across their bodies, along with their sounds being different.
Yellow-bellied Flycatcher (Empidonax flaviventris)
Okay, let's start off nice and easy. In the east, this flycatcher is the only one with yellow underparts, distinguishing it from Least, Alder, Acadian, and Willow. However, the two Western Flycatchers (Pac-slope and Cordilleran) also are yellowish under. It has a stubbier bill and head, and the yellow in the belly is brighter and there is more of it.
Acadian Flycatcher (E. virescens)
This bird is only found in the eastern US. It is larger and greener than any other empid. It is most similar to the Alder and Willow Flycatchers, but its green is a lighter shade with more hue. It is much larger and greener than the Least Flycatcher. Its call, a very fast pee-dzee call.
Alder Flycatcher (E. alnorum)
This bird is very similar to the Willow Flycatcher. It lives in moist thickets unlike the Willow Flycatcher's habitat of brushy areas. Its sound is also different, a fee-bee-o instead of the Willow Flycatcher's fi-beew. It is a plain, olive-colored flycatcher that is distinguished from the Least Flycatcher by having a less prominent eyering.
Willow Flycatcher (E. traillii)
This bird is similar to the Alder Flycatcher, as mentioned before. It is only told apart by voice. Acadian and Yellow-bellied Flycatchers are brighter, while the Least Flycatcher has an eye ring. In the West, most other flycatcher (besides the Gray Flycatcher) have eye rings to tell them apart.
Least Flycatcher (E. minimus)
The Least Flycatcher is the smallest of the Empidonax flycatchers. Its large eyering distinguishes it from the other Eastern flycatchers. It is much greener than the Hammond's and Gray Flycatchers. They have a white belly that also distinguishes them from the other emipds. Their call is a chee-bee! Its bill is also shorter than any eastern empid.
Hammond's Flycatcher (E. hammondii)
The first empid endemic to the western US, the Hammond's Flycatcher is a small, grayish flycatcher with a huge eyering. It has a gray head and a greenish body. It is very similar to the Gray Flycatcher except it has green on the lower body. It also has more dark on the lower mandible than the other empids. Unlike a lot of empids, the call is a one-syllable peek.
Gray Flycatcher (E. wrightii)
This bird is the plainest and grayest of all the empids. It is very similar to the Hammond's Flycatcher. However, it is much grayer and lighter-colored. It is also larger than the Hammond's and Least Flycatchers. While most flycatchers are greener and darker colored, some birds may appear lighter in the field.
Dusky Flycatcher (E. oberholseri)
This one closely resembles the Gray and Hammond's Flycatchers. However, the Gray is a bit lighter, and the Hammond's is slightly smaller and darker. Its downward tail-bobbing is distinctive among empids; never take behavior out of the equation when ID'ing birds. Its main call is a pir-EET sound. Its call, like the other empids, is the main way to tell it apart from others.
Cordilleran Flycatcher (E. occidentalis)
This bird is darker on the belly than most empids. It and the Pacific-slope Flycatcher are probably the hardest to tell apart in their small range intergrade. They were formerly known as one species, the Western Flycatcher. The Pac-slope Flycatcher is slightly smaller and darker, but it is hard to tell in the field. Most of their ranges are separated, but the pi-PEET call is different from the Pac-slope's three-syllable call.
Pacific-slope Flycatcher (E. difficilis)
Lastly, this one is very hard to tell apart from the Cordilleran Flycatcher. Its three-syllable call is the main way to tell the two apart. It is also slightly smaller and darker. It is extremely similar so you can just hope that you are not in the small range intergrade where they both live. Most people aren't but it is still somewhat useful to know the small tips for telling them apart.
Other Similar Species
Buff-breasted Flycatcher (E. fulvifrons) - This empid is structured the same, but it is smaller and, as the name would suggest, more buffy. It is only found in southern Texas, however. It is the only American empid not mentioned above.
Northern Beardless-Tyrannulet (Camptostoma imberbe) - This bird is much more plain than the others, but sometimes variation causes a yellow belly. It is much grayer than others and its range only occupies the southern areas of the United States. Its range also goes down to Central America.
Vireos (Vireo sp.) - The vireos are the closest relatives to flycatchers in the US. The Hutton's Vireo is the most similar, but the head shape is different. The flycatchers also exhibit tail-bobbing and different behaviors. The vireos, for the most part, are also paler and the calls are different.
Okay, let's start off nice and easy. In the east, this flycatcher is the only one with yellow underparts, distinguishing it from Least, Alder, Acadian, and Willow. However, the two Western Flycatchers (Pac-slope and Cordilleran) also are yellowish under. It has a stubbier bill and head, and the yellow in the belly is brighter and there is more of it.
Acadian Flycatcher (E. virescens)
This bird is only found in the eastern US. It is larger and greener than any other empid. It is most similar to the Alder and Willow Flycatchers, but its green is a lighter shade with more hue. It is much larger and greener than the Least Flycatcher. Its call, a very fast pee-dzee call.
Alder Flycatcher (E. alnorum)
This bird is very similar to the Willow Flycatcher. It lives in moist thickets unlike the Willow Flycatcher's habitat of brushy areas. Its sound is also different, a fee-bee-o instead of the Willow Flycatcher's fi-beew. It is a plain, olive-colored flycatcher that is distinguished from the Least Flycatcher by having a less prominent eyering.
Willow Flycatcher (E. traillii)
This bird is similar to the Alder Flycatcher, as mentioned before. It is only told apart by voice. Acadian and Yellow-bellied Flycatchers are brighter, while the Least Flycatcher has an eye ring. In the West, most other flycatcher (besides the Gray Flycatcher) have eye rings to tell them apart.
Least Flycatcher (E. minimus)
The Least Flycatcher is the smallest of the Empidonax flycatchers. Its large eyering distinguishes it from the other Eastern flycatchers. It is much greener than the Hammond's and Gray Flycatchers. They have a white belly that also distinguishes them from the other emipds. Their call is a chee-bee! Its bill is also shorter than any eastern empid.
Hammond's Flycatcher (E. hammondii)
The first empid endemic to the western US, the Hammond's Flycatcher is a small, grayish flycatcher with a huge eyering. It has a gray head and a greenish body. It is very similar to the Gray Flycatcher except it has green on the lower body. It also has more dark on the lower mandible than the other empids. Unlike a lot of empids, the call is a one-syllable peek.
Gray Flycatcher (E. wrightii)
This bird is the plainest and grayest of all the empids. It is very similar to the Hammond's Flycatcher. However, it is much grayer and lighter-colored. It is also larger than the Hammond's and Least Flycatchers. While most flycatchers are greener and darker colored, some birds may appear lighter in the field.
Dusky Flycatcher (E. oberholseri)
This one closely resembles the Gray and Hammond's Flycatchers. However, the Gray is a bit lighter, and the Hammond's is slightly smaller and darker. Its downward tail-bobbing is distinctive among empids; never take behavior out of the equation when ID'ing birds. Its main call is a pir-EET sound. Its call, like the other empids, is the main way to tell it apart from others.
Cordilleran Flycatcher (E. occidentalis)
This bird is darker on the belly than most empids. It and the Pacific-slope Flycatcher are probably the hardest to tell apart in their small range intergrade. They were formerly known as one species, the Western Flycatcher. The Pac-slope Flycatcher is slightly smaller and darker, but it is hard to tell in the field. Most of their ranges are separated, but the pi-PEET call is different from the Pac-slope's three-syllable call.
Pacific-slope Flycatcher (E. difficilis)
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| Buff-breasted Flycatcher |
Other Similar Species
Buff-breasted Flycatcher (E. fulvifrons) - This empid is structured the same, but it is smaller and, as the name would suggest, more buffy. It is only found in southern Texas, however. It is the only American empid not mentioned above.
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| Northern Beardless-Tyrannulet |
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| Hutton's Vireo |
