Hi Jim- As you probably know, this group of Tyrant flycatchers are notoriously difficult to ID by image alone. You are correct that this is an Empidonax flycatcher- the overall coloration strongly suggests this genus. But that's where the problem begins. There are 5 species in this genus in s. Ontario. I have most experience with the common ones out east (Alder and Least) and almost invariably tell them apart by song/call. Acadians like hardwoods. The eye-ring, shape of top of head and throat area all look good of Acadian IMO. Sibley notes the long primaries projecting down the tail while at rest but unfortunately they are not really visible here (any other images showing this?). If we really can see the left primary tip in this image then it looks too short for Acadian.
And now as a scientist I'll throw out a hypothesis:
That most Empidonax flycatchers are not reliably IDed to species by look alone.
The hypothesis is tested by setting up a panel of experts and presenting each (double-blind) with a series of images of known Empidonax species. Success rate is compared with random choice.
To be honest I haven't got a clue what the results of this study would be- in other words I'm not confident it can be done.
John: Actually many empidonax flycatchers are reliably identifiable by photo if the marks are shown clearly. There are some pairs that can be tricky (Hammond's / Dusky) and some that are impossible (Willow / Alder, Pacific-Slope / Cordilleron) but a lot of the others are straightforward for those who put in the study time. Unfortunately, I'm not one of them.
Still, I've done a little study so I'll stick my neck out just a little. I think this bird is probably an Acadian. The head is a bit on the grayish side but the yellowish lower mandible looks good, the bill looks fairly long (though angles can be deceiving in a photo), and the yellowish wash looks pretty extensive.
Jim: Do you have a shot from the side? I'd really like to see the following:
a) The length of the outer primaries compared to the inner primaries (called "primary extension") which is long in Acadian.
b) Color of the back (greenish in Acadian).
c) Length of tail (longish in Acadian).
If anybody is interested in an example of "primary extension", there's two photos you can compare nicely over on BirdFellow (links below). If you look at the Acadian, you'll see two longest primary tips showing are close together, then there's a bit of a gap, and then the rest of the primary tips are all close together. In the Least Flycatcher, most of the primary tips are fairly close together with little gap between the longest tips and the shorter ones. This can vary with primary growth, position, and photo angle but it works fairly well and is a mark used by the experts to include/exclude species from consideration when trying to ID an empidonax.
Agreed Paul. I was being a bit hyperbolic. Even I think I could tell a Yellow-belly from a Least.
The point I wanted to make about the experiment is really a conceptual one. It is my experience that science is rarely if ever applied to the pronouncements of bird watchers and I think it should be in some cases. In science it's just not good enough to say something without scientific evidence, and it doesn't matter how convincing or convinced the observer is. Do I believe that observers can tell a Greater from a Lesser Snow Petrel in the field?- not for a moment, without evidence at least. The same can be said for many of the prions, and the proliferating number of wandering albatross species, and I think for several of the Empidonax flycatchers, at least visually; I could go on. I am not questioning that in theory it is possible, just that until the method is challenged and the results verified scientifically, the pronouncements remain an open question unless you are willing to take them on faith- I'm not. How you answer those questions is a huge challenge but just because they are difficult to answer does not mean you don't ask them.
I don't think it's ever been approached scientifically, but some "science lite (tm)" has certainly been applied to some of these ID problems. For empidonax they used singing birds, banded birds, and museum specimens so they knew the ID. That's how most of the marks were worked out in the first place.
The funny thing is that I read about a hawk banding station that was right up the ridge from a hawk watch site. They did an experiment with the Cooper's and Sharp-shinneds they caught. The birds were ID'd in the hand and released. They radioed the hawk watch which was within sight to tell them that an accipiter had just been released. Apparently the identifications made by the hawk watch weren't always ... stellar. But to quote Pete Dunne (no, it wasn't the Cape May Hawkwatch) who had his tongue firmly planted in his cheek, "you may be right but I'm official."
Thanks for the information and time. I believe this is the only image that I kept but will check my other memory cards. Paul I recall the back having a greenish colouration. Thanks again John and Paul.
Flycatcher
Posting Permissions
Reply With Quote