Conseils pour identifier les moucherolles du genre Empidonax

Empidonax flycatchers are among the most intimidating of identification problems for birders in North America. Numerous attempts have been made to disentangle the intricacies and confusing variability of their plumage and structure. « The Empidonax Challenge » by Bret Whitney and Kenn Kaufman, consisting of close to 50 pages (in five separate installments), was published in Birding in the mid-1980s. The members of this genus which live in the Eastern United States and that include Yellow-bellied, Acadian, Alder, Willow, and Least Flycatchers have the reputation of being nearly impossible to identify in the field unless their vocalizations are heard.
The 25th of September 2010, an Empidonax Flycatcher was found at Blakeney Point, Norfolk, United-Kingdown, attracting more than a thousand birders. First reported as a Yellow-bellied Flycatcher, it was then considered as a ‘Traill’s Flycatcher’ a term used to describe two very closely related spp, Alder and Willow Flycatcher. A few even believe it is was Least Flycatcher. But as the bird was not heard calling or captured and measured, it will be nearly impossible to determine which species it is with certainty.
Bernhard Pusch went to the Blakeney Point the 27th of September, and he took some photos. He gives us his opinion about its identification.
In this article, we present you how to look and what to look for when you find an Empidonax flycatchers, the use of morphometric ratios in their identification and the two discriminant formulas described in Pyle’s Identification Guide to North American Birds Part I (1997).