Alder flycatcher  The alder flycatcher ("Empidonax alnorum") is a small insect-eating bird of 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". "E. alnorum" is one of the larger "Empidonax" species, attaining a length of 13–17 cm, and a mass of 12–14 g. 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-peewee ("Contopus virens") and the eastern phoebe ("Sayornis phoebe"), but "E. alnorum" can be distinguished by its smaller size and upward tail flicking behavior. Birds in the genus "Empidonax" are notoriously hard to identify. 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 alder flycatcher is sibling species with the willow flycatcher ("E. trailli"). The two species were grouped together as one species, the Traill's flycatcher, until 1973, when differences in vocalizations and habitat use lead to their acknowledgement as distinct species, which has since been supported by genetic data. A study analyzing the genetic makeup of 12 "Empidonax" species found that the Alder and Willow Flycatcher are each other's closest relatives. The Tyrant flycatcher genus is closely related to the Wood-Pewee genus ("Contopus"), and a hybrid of the two genera was reported to have been caught in Idaho.