The alder flycatcher (Empidonax alnorum) is a small insect-eating bird in the tyrant flycatcher family. The genus name Empidonax is from Ancient Greek empis, "gnat", and anax, "master". The specific alnorum is Latin and means "of the alders".

Description

E. alnorum is one of the larger Empidonax species, attaining a length of , and a weight of . The upperparts of E. alnorum are dull greenish-olive. The crown is a slightly darker olive-green than the back. The throat is white, with a darker breast band. Thin white rings surround the eyes. The bill is wide and moderate in length, with pinkish or yellow-orange lower mandible and black upper mandible. Wings are generally black, with white wing bars and white edges of the innermost secondaries (tertials). Juveniles have brownish upperparts, yellow underparts, and yellowish brown or buff wingbars.

E. alnorum is similar in appearance to the eastern wood pewee (Contopus virens) and the eastern phoebe (Sayornis phoebe), as well as the nearly identical willow flycatcher (Empidonax traillii) but E. alnorum can be distinguished by its smaller size and upward tail flicking behavior. Novel approaches to identification have been employed to try and increase the accuracy of species identification of mist-netted individuals, such as using ratios of and differences between the measured lengths of various body parts, including wings and beaks. Vocalizations are often relied upon for identification to species in the field when birds cannot be manipulated by hand. The ratio of the lengths of the primary feathers is a useful distinction with birds in the hand or on good quality profile photographs.

Taxonomy

The alder flycatcher is sibling species with the willow flycatcher (E. trailli). A study analyzing the genetic makeup of 12 Empidonax species found that the Alder and Willow Flycatcher are each other's closest relatives. The genus Empidonax is closely related to the pewee genus (Contopus), and a hybrid of the two genera was reported to have been caught in Idaho.

Habitat and distribution

The summer breeding range of the species covers most of Canada and Alaska, descending to a southernmost point in the northeastern United States. During migration, the species occupies humid and semi-arid habitats, including forest edges and fields at elevations up to .

Behavior

Vocalizations

The vocalizations of the alder flycatcher are very useful for its identification in the field. The song is a distinct "fee-bee-o"; birds have been observed to throw their heads back and shake their tails while singing. Insects are captured during flight or gleaned from the foliage of trees. and is a U.S.-Canada Stewardship species.

References

  • Alder Flycatcher - Empidonax alnorum - USGS Patuxent Bird Identication InfoCenter
  • Alder Flycatcher Species Account - Cornell Lab of Ornithology
  • Alder Flycatcher- Boreal Songbird Initiative