Yellow-bellied Flycatcher (Empidonax flaviventris)

OTHER NAMES: N/A
Latin Etymology: Empidonax ("mosquito lord") flaviventris ("yellow bellied")

Yellow-bellied Flycatcher (Empidonax flaviventris) at Location, Costa Rica - November 2025

Featured Subspecies: N/A
Weight: 8.5-17g  /  Length: 13-15cm  /  Wingspan: 18-20cm
NO UK STATUS / IUCN Red List: Least Concern

With a breeding range comprising most of Canadas wet boreal forests as well as and Wisconsin, Minnesota and Michigan, then migrating to Central America in Winter. They nest near ground level in cup like strucutres made of sphagnum moss. 

Related Species: 
Order: Passeriformes
Family: Tyrannidae
Genus: Empidonax
SUBSPECIES: none - monotypic 
 
- Sighting Locations - 

COSTA RICA - Spanish - Mosquero Ventriamarillo

A widespread Wintering species.
- COSTA RICA 2025 TRIP: Seen at Tarcoles 

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Black-capped Flycatcher (Empidonax atriceps)

OTHER NAMES: N/A
Latin Etymology: Empidonax ("mosquito lord") atriceps ("dark head")

Black-capped Flycatcher (Empidonax atriceps) at San Gerardo de Dota - November 2025

Featured Subspecies: N/A
Weight: 9g /  Length: 10-12cm  /  Wingspan: ?
NO UK STATUS / IUCN Red List: Least Concern

An endemic of the Talamancan Montane Forests in Costa Rica and Panama, they are found above 1850m, particularly in Oak Forests, and are largely sedentary, although their may be some seasonal altitudinal movement. As is usual for empidonax flycatchers, it hunts by hawking from a set post to catch insects in flight.
 
Related Species: 
Order: Passeriformes
Family: Tyrannidae
Genus: Empidonax
SUBSPECIES: none - monotypic 
 
- Sighting Locations -

COSTA RICA - Spanish - Mosquero Cabecinegro
Common in Montane Forests
- COSTA RICA 2025 TRIP: Seen at San Gerardo de Dota

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Least Flycatcher (Empidonax minimus)

OTHER NAMES: Chebec, Chebecker
Latin Etymology: Empidonax ("mosquito lord") minimus ("smallest")

Adult Least Flycatcher (Empidonax minimus) at Buffalo Creek State Park, Minnesota, USA - July 2024

Featured Subspecies: N/A 
Weight: 10g  /  Length: 12-14cm  /  Wingspan: 19-22cm
NO UK STATUS / IUCN Red List: Least Concern

The smallest member of the infamous Empidonax flycatcher complex in Eastern North America. They migrate to Central America for Winter.  While they can be differentiated in the field visually by experienced birders, I must admit I relied on audio recognition software to confirm the ID based on it's more distinctive song.

Related Species:
Order: Passeriformes
Family: Tyrannidae
Genus: Empidonax
SUBSPECIES: none - monotypic 

 - Sighting Locations -

UNITED STATES - Breeds primarily in Northern Border States of the Lower 48
 - CHICAGO TO ALASKA ROADTRIP 2024: Several in Minnesota

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Alder Flycatcher (Empidonax alnorum)

OTHER NAMES: N/A
Latin Etymology: Empidonax ("mosquito lord") alnorum (of the alders)

Adult Alder Flycatcher (Empidonax alnorum) at Potter's Marsh, Anchorage - August 2024

Featured Subspecies: N/A
Weight: 12-14g/kg  /  Length: 13-17cm  /  Wingspan: 8.3-9.3cm
NO UK STATUS / IUCN Red List: Least Concern

A member of the notoriously difficult to differentiate empidonax genus, the alder flycatcher is most easily differentiated by it's call which sounds like it's calling "free beer!". As the name suggests, they breed in wet thickets of alder as well as maple and birch. It's closest relative is the Willow Flycatcher although outside of migration their overlap zone is comparatively small.

Related Species:
Order: Passeriformes
Family: Tyrannidae
Genus: Empidonax
SUBSPECIES: none - monotypic 

 - Sighting Locations -

UNITED STATES - Breeds in Alaska and the North East of the Lower 48. Passage elsewhere.
 - CHICAGO TO ALASKA ROADTRIP 2024: Several seen near  Anchorage, Alaska 

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Willow Flycatcher (Empidonax traillii)

OTHER NAMES: N/A
Latin Etymology: Empidonax ("mosquito lord") traillii (named for Thomas Stewart Traill)

Willow Flycatcher (Empidonax traillii) at San Jose - August 2022

Featured Subspecies: Unknown
Weight: 13.5g  /  Length: 13-15cm  /  Wingspan: 22cm
 NO UK STATUS / IUCN Red List: Least Concern

The willow flycatcher is a widely distributed member of the infamous Empidonax genus, and is found throughout much of the continental USA. In the field, it is only clearly distinguishable from the Alder flycatcher by song, but that species isn't found regularly in California and most of it's breeding range is in Canada. This individual was seen when caught in mist nets by authorised handlers in San Jose, and was the only individual of the species we saw during the week.

Related Species:
Order: Passeriformes
Family: Tyrannidae
Genus: Empidonax
SUBSPECIES: E. t. adastus, E. t. brewsteri, E. t. extimus, E. t. traillii

 - Sighting Locations -

UNITED STATES 

Found widely across most of the Northern Lower 48
 - CALIFORNIA 2022 TRIP: Seen at San Jose 

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Pacific-slope Flycatcher (Empidonax difficilis)

OTHER NAMES: Western Flycatcher (former combined species name) 
Latin Etymology: Empidonax ("mosquito lord") difficilis ("difficult")

 

Adult Pacific Slope Flycatcher (subspecies E. d. difficilis) at Berkeley, California - August 2022

Featured Subspecies: Empidonax difficilis difficilis
Weight: 9-12g  /  Length: 12cm  /  Wingspan: 20-23cm
NO UK STATUS / IUCN Red List: Least Concern

A species of the infamously hard to identify "empid" complex, they are unrelated to the old world flycatchers and are in fact a part of the Tyrannides clade - a group found exclusively in the Americas that contains a diverse range of colourful species. This species' closest relative is the Cordilleran Flycatcher, which is was formerly considered part of the same species (the Western Flycatcher) but is at a point where the two species are considered indistinguishable in the field, only separated by voice of the male.

Related Species: 
Order: Passeriformes
Family: Tyrannidae
Genus: Empidonax
SUBSPECIES: E. d. difficilis, E. d. insulicola, E. d. cineritius

 - Sighting Locations -

UNITED STATES 
Breeds along West Coast States including Alaskan panhandle.
 - CALIFORNIA 2022 TRIP: Seen at  Berkeley and San Jose

 Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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