April 26th, 2020: It’s empidonax time!
Everyone loves a killer ID challenge, right? Well, it’s empid season and my local Queen Elizabeth Park is just about the best spot during their migration. I’ll be there pretty much daily for the next few weeks, watching as the birds shift gradually and hoping to find some of the rarer migrants.
As it turned out, one of my first days there already brought a Dusky Flycatcher! Other birders found it first and reported it. But I was thrilled to see one of these guys! I’ve never actually seen or heard a Dusky before, despite numerous efforts. I even thought I might have seen them in previous years, but was never able to get a proper look, and they weren’t calling in the past.
The little guy called as soon as I got to the spot with the other birders, and then promptly vanished… Fortunately, I caught up with him by myself later and at a different location. And I got to savour my time with this rare migrant.
Dusky Flycatchers actually come through Vancouver every year. But we’re technically outside their range, which extends all the way along western North America, except for the coast. So it’s really only in early migration that we see any come through with the first batch of Hammond’s Flycatchers. One or two Duskies are typically reported in Vancouver each spring, and they’re typically seen at QE Park. Still, they’re painfully similar to other empidonax flycatchers (the little ones that all look the same), so I think they’re probably undercounted.
Empidonax flycatchers (from the Greek empis for “gnat” and anax for “master”) are notoriously challenging IDs for birders. There are very few reliable field marks between species. And some of them barely even distinguishable in the hand (most notably Willow and Alder Flycatchers). Fortunately, their songs and calls differ noticeably, if not obviously.
I’m not going to write out an ID masterclass here. But I’ll give you my indicators for the troublesome empids we get in the PNW. Buckle up.
Our most common nesting empids are Willow and Pacific-slope Flycatchers. Habitat helps a lot for these two, with Willows primarily in riparian habitat and Pac-slopes in forest or woodland. Pac-slopes are also a greeny-gray with dingy wing bars and conspicuous wide eye ring, while Willows are lighter overall and have a much fainter eye ring (often not visible). Their calls and songs are easily distinguished too.
Hammond’s Flycatcher might be confused with Pac-slopes showing less green, especially in low light. But Hammond’s only come through in migration, and though they arrive ahead of the Pac-slopes, there is plenty of time overlap in early May. If you’re looking at a really gray, small empid in a woodland in late April or early May, you’re most likely looking at a Hammond’s. But I still wouldn’t bet on it…
Your best bet, and really the only sure-fire ID distinction, is the “primary projection.” Primary projection is how the primaries (outermost flight feathers) project down past the tertials (shorter, inner flight feathers). Birds with longer primary projections appear to be shorter-tailed because the wings obscure part of its length. Hammond’s Flycatchers always (this is the only always) have slightly longer primary projections than Pac-slopes. Everything else can be helpful, but can’t cement the ID on its own (unless your bird is really green, then it’s a Pac-slope). This means that other possible field marks, like the Hammond’s generally squarer-looking head, slightly less obvious teardrop back of the eye ring, grayer colouring, etc., can be very useful, but not definitive on their own.
Finally: Dusky Flycatcher. This particular empid often looks so much like Hammond’s Flycatchers that without a really trained eye and a really good long look, it’s very difficult to separate the two.
Duskies have a very short primary projection, making them appear quite long-tailed, compared to Hammond’s. They also tend to have rounder looking heads than Hammond’s. [As I write this a little late, I’ve had a chance to stare at about 5 more Duskies (SO MANY of them this year!) and also noticed that the Duskies coming through the park have noticeably lighter lores than any of the Hammond’s. I don’t know how reliable this is though, so I’ll have to compare again in future years and in other locations in the PNW.]
As with the other empids though, your best bet is still sound, even though Hammond’s and Dusky songs and calls are quite similar. At QE today, the visible difference seemed clear already, as I stared at the Dusky’s short primary projection and more rounded head. Then, when I heard it call, I knew this was it!
It wasn’t all flycatchers today though (eBird list)! The warblers are really pouring in now. Yellow-rumped, Orange-crowned, Wilson’s, Townsend’s, and Black-throated Gray Warblers are all here now (though not yet in large numbers).
There was even a bonus Nashville Warbler today!
Tomorrow, there will be even more!! =)