I am creeping every closer to my long-sought goal of 500 birds on my life list. In pursuit of that goal, I have made a list of species that (1) I haven’t seen and (2) I have a good chance of seeing in Colorado.
Two of these are Tyrant Flycatchers of the genus Empidonax. The 11 “Empids” all look extremely similar and I’ve never pretended to be able to tell them apart by sight.
The field guides are full of statements like these:
- Plumage and structure can be so similar among species within the various genera that voice is the primary field mark.
- At any season it is possible to see individuals of the same species with contrastingly different plumage wear.
- Eleven confusing little birds, with wing-bars and (usually) eye-rings, all looking very much alike.
- Their specific characters are so subtle that there is often more variation within a species than there is between any two species in the genus.
Up till now, if I see an Empid that isn’t singing, I haven’t counted it. But on the rare occasions when I find myself in the company of other birders, I have happened upon a few individuals who don’t hesitate to call out a species based on plumage alone. A little gray-green bird will land on a branch 70 feet away in a wood lot and some guy will immediately say “Willow.” That bird will fly off into the woods and, five minutes later, another one will land on another branch. I always figure it’s the same bird. But the expert will call out, “Least.”
I’ll be honest—I’m a skeptic. How do they know if they’re right? Are they so confident because they are actually able to detect minor differences in bill color or primary extension? Or are they confident because they know nobody will be able to prove them wrong?
Recently, Nate and I were birding on the Vindicator Valley Trail at 10,000 feet. Pikes Peak loomed in the near distance. I saw a small flycatcher perched at the top of a small bush near the ruins of an old gold mine. It wasn’t just sitting there. It was singing.
A couple of years ago, I identified a Dusky Flycatcher not far from this very spot, based on song and habitat. Was this another Dusky? Or was it a Hammond’s, one of the species I needed for my life list? I pulled up the songs of the two birds on my phone app and read this: “Song of the Dusky Flycatcher is similar to that of Hammond’s Flycatcher.”
Great. A species that can only be positively identified by song, and the song isn’t noticeably different from an identical-looking species that inhabits the same areas.
The bird flew down and landed on a fence post and gave me great looks. I tried to see bill color, breast pattern, primary extension, tail length … I even took some video, but the bird made no noise.
The primaries looked … I couldn’t tell. The tail seemed short. The “vest” on its breast was obvious. The bill was yellow at the base. All this was consistent with Hammond’s. It didn’t sing often—maybe three or four times. I thought I could detect a similarity to the Hammond’s song. The bird flew back up hill. We walked the trail and 10 minutes later were back in the same area but up slope. An Empid was making a “che-bek” call that reminded me of the Least Flycatcher more common in the east.
I was about 70% convinced I’d seen a lifer. We walked on. Half an hour later, low in the middle of a stand of short aspen was another Empid. I immediately thought the tail on this one looked longer—like a Dusky tail was supposed to look. To test my theory, I played the song of a Dusky Flycatcher. The bird flew across the trail and landed above our heads in another Aspen, not 20 feet away. It even sang a few times. I thought the song sounded higher-pitched, and it definitely had more syllables. So this was a Dusky, right? Especially considering that it had flown to the perch when I played a Dusky song.
I even recorded this one’s song.
When we’d circled around and were back near where we’d seen the first one, we saw one again. This one looked longer-tailed also. Had we been looking at three birds, two birds, one bird? I had no idea.
I decided to solve my problem the easy way. I posted videos of bird one and bird two on the Denver and Colorado Field Ornithologists Facebook pages and asked for help. One person said bird one was a Dusky and bird two was a Hammond’s—the reverse of what I’d figured out. Another guy said much the same thing. A third guy, with great confidence, said that bird two was a Dusky and bird one was unidentifiable.
Like I suspected.
I may never add a Hammond’s Flycatcher to my list.