Sunday, June 3, 2012
Empid ID in 3 easy steps
I don't need to tell you that flycatchers of the genus Empidonax--Empids--rarely look like the images in the field guide. Humans naturally put more emphasis on color and the face when first trying to identify a bird. That will lead you down the wrong path when it comes to identifying Empids. The bird above is identifiable anywhere in North America just by what you can see in the photo above. In fact, this bird is in the perfect position for identification purposes! That's a good thing because that's how you often see these birds--above you in the forest gloom, strongly back lighted. Such conditions are the photographer's nightmare, as these poor photos show!
First, of course, you have to identify it as a flycatcher--big head, wide flat bill, upright posture, sits still for a long time then sallies out to catch an insect and then often returns to the same perch. Once you have identified your mystery bird as some type of tyrant flycatcher--the world's most numerous family of birds with over 400 species--your work really begins!
Empids are tiny flycatchers. They are larger than a kinglet, of course, but equal or smaller than a junco, depending upon species. They are drab olive or gray, with obvious white wingbars and an eyering (not strongly marked in the Willow Flycatcher). In the shade the belly often looks yellowish and the upperparts of most species have a greenish cast. But that hint of color often disappears in direct sunlight.
Let's take a closer look at the bird above.
The end of the secondary stack (A) on Empids is obvious from nearly all angles. The primaries (B) stick out from under them. On Empids with short primary extension A and B above would be nearly together. Thus, this bird has long primary extension. Only one-third of the Empids in North America have long primary extension.
[Please note that long primary extension is related to, but not the same thing as, long winged, which is a comparison of how far down the tail the primary tips extend; in other words, B to the end of the tail. You can use that measure, too, but don't get these two different wing comparisons mixed up.]
Next on to the bill. No, I didn't misdraw an arrow pointing to the bill. The line at C in the photo above is parallel to the bill to show how straight the edges of the bill are. Many Empids have strongly convex bills, bulging in the middle. The sides of the bill of this bird is very straight compared to most others in North America. In addition, the mandible on this bird is rather short, and thin at the base compared to other Empids.
Now you can look at the color of the bill. It is mostly dark underneath. Only one species of Empid in North America has more than half dark lower mandibles. Many species have orangish or yellowish or pinkish under-mandibles, some with dark tips of varying extent.
That's it. A-B-C. 1-2-3. Primary extension, bill shape, lower mandible color pattern.
In the Pacific Northwest:
Long primary extension: Hammond's Flycatcher
Long to medium primary extension: Western Flycatcher (Pacific-slope/Cordilleran)
Short to medium primary extension: Least Flycatcher
Short primary extension: Willow Flycatcher, Dusky Flycatcher, Gray Flycatcher
Straight sides to narrow, short bill: Hammond's Flycatcher
Straight sides to narrow, medium length bill: Dusky Flycatcher
Straight sides to narrow, long bill: Gray Flycatcher
Convex sides to wide, short bill: Least Flycatcher
Convex sides to wide, long bill: Western Flycatcher, Willow Flycatcher
Mostly dark lower mandible: Hammond's Flycatcher
Mostly pale lower mandible with dark tip up to 1/3 of length: Least Flycatcher, Dusky Flycatcher
Mostly pale lower mandible with small dark tip: Gray Flycatcher
Mostly or entirely pale lower mandible: Western Flycatcher, Willow Flycatcher
Once you get these first three items categorized, you can go on to other supporting characters such as throat color (yellow, gray, or white) and contrast with breast, eyering shape and color, head shape, tail bobbing or wing-flicking behavior. But if you don't start with the 3 essential ID characters explained above, the other more subjective marks can throw you off. Once you get a wrong first impression based on one of these supporting characters it is very hard to come back to the correct identification on your own!
Of course, on the breeding grounds these birds are incessant morning singers. and it is so much easier to hear these birds than get a good look!
I photographed this Hammond's Flycatcher on June 1, 2012 in the northern Oregon Coast Range at Reeher Camp near the town of Timber.
And now, because I know you really do want to see the face, I present this same bird. Here's looking at you, kid!