Welcome to the world of Empidonax genus flycatchers. I know, they stink horribly with mis-identification, riiiiiight? Well, I think these birds are actually neat to study. Call me crazy, but I enjoy Empids (name in short for these flycatchers) like some enjoy four-year gulls or sandpipers. This genus of flycatchers are best told by voice, but are separable in the field by careful observations. These birds are olive-green/gray/brown tones in nature with usually two distinct wing bars. They sit-upright and occupy a variety of habitats from sagebrush (Gray Flycatcher) to dense eastern hardwoods (Acadian Flycatcher). Typically have contrasting throats and bellies are are very active insectivores. Wood-Pewees have caused confusion in the past, but pewees are larger, longer-tailed, longer-winged, and sit motionless for minutes at a time. Furthermore, most empids are active and flick their tails often.
I was scoping a local water source, Cherry Creek State Park here in Denver, Colorado yesterday. Had some neat things on the water, but I happened upon this empid in an American Plum tree. I immediately got excited, because I knew I was going to have to work my brain for this ID. I'll take you through my thought process.
The contrasting throat, yellowish undertones, and wing bars told me this was an empid right off the bat. If we look closely, we can see the lack of an eye-ring and the photo above shows an entire yellow lower mandible. In Colorado, birds like Hammond's and Dusky Flycatchers have smaller bills with only half the lower mandible yellow, so they can be eliminated. The eye-ring is next and a HUGE clue. Cordilleran Flycatcher has a pronounced eye-ring with a slight tear-drop towards the back end. This is not a Cordilleran! Least has smaller proportions overall and has an eye-ring as well. Alder has a contrasting white throat and a yellowish lower mandible the entire length of the bill. Hmmmm, fits the description for our bird, doesn't it?
Okay, since this bird was not making any noise I need to look at other attributes. Willow and Alder Flycatcher were once considered the same species (Traill's Flycatcher), but are now split so the similarities are closer than normal. Color should be avoided most of the time since empids go through serious fall molt that washes them out with yellow. Nevertheless, this plumage looks really fresh (sharp, pointy flight feathers and clean appearence) so this bird might be a younger individual. What about Willow Flycatcher? Willow's are very variable and there are multiple subspecies across the nation, but they typically have a very brownish overtone. This bird has just that. This bird was flicking it's tail often which is a habit of many Willow Flys. The shorter wings and longer tail appearence lean towards Willow over Alder (especially in the west where the western Willow Flys have shorter wings than in the east). One last thing that I associate Willow Flycatcher's having is a pronounced peaked crown at the nape. This bird certainly has that as well.
All these clues and still I had to ask some other people for confirmation. Be very careful with Emidonax identification in the field! I actually decided to step back and try my new Nikon EDG 65mm Fieldscope to view the bird to get a better grasp on some of the finer features. The clarity and light absorption capabilities are unbelievable. The crispness from edge to edge allows for a maximum sharp field of view. This bird sat still for a while, but just as I was about to digiscope the little guy he flew farther into the bush.
Okay, so lets recap!
-yellow lower mandible
-lack of eye-ring (huge key)
-appearence of long tail
-constant tail bobbing
-close proximity to the ground
-contrasting white throat
Given all of these characteristics I identified this bird as a Willow Flycatcher. I love these guys! Take care and please let me know your thoughts or ask questions if you have them.
All photos were taken with a Nikon D200 and a 300mm F4 Nikkor lens. Good Birding!
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