Erlenschnäppertyrann

Bestimmung

E. alnorum is one of the larger Empidonax species, attaining a length of 13–17 cm (5.1–6.7 in), and a mass of 12–14 g (0.42–0.49 oz). The wingspan ranges from 8.3–9.4 cm (3.3–3.7 in). 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.<p>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.<p>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.

Taxonomie

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.

Wissenschaftlicher Name

Empidonax alnorum

Autorität

Brewster, 1895

Ordnung

Passeriformes

Familie

Tyrannidae

Gattung

Empidonax

Verbreitung und Lebensraum

The summer breeding range of the species covers most of Canada and Alaska, descending to a southernmost point in the northeastern United States. In autumn, E. alnorum migrates south through the eastern United States, Mexico and Central America, wintering in the western range of South America.<p>In the summer breeding season, E. alnorum occupies wet, dense, shrubby thickets of alder (Alnus sp.), maple (Acer sp.), and birch (Betula sp.) at elevations below 1,300 ft (400 m). During migration, the species occupies humid and semi-arid habitats, including forest edges and fields at elevations up to 2,500 ft (760 m). Early successional scrubby vegetation or woodland edges are preferred habitats in winter, particularly those near water and below 1,100 ft (340 m).

Brutgebiet

NA : c Alaska to e canada and ne USA

Überwinterungsgebiet

nw and wc SA

Zugverhalten

Vollzieher

Verhalten

Zugverhalten: Vollzieher.

Schutzstatus

Bestandstrend: rückläufig.

Bestandstrend

rückläufig