Least vs Dusky Flycatchers

Steve Hampton


There's been a lot of debate in various forums about the March empid in north Davis, which was originally thought to be a Dusky Flycatcher. A growing list of people now believe it to be a Least Flycatcher. At the time, I did not even consider this option (and have limited familiarity with Least). I am now in the "Least camp" on this bird, after considerable review. 

The best pics are by Kirk Swenson at https://ebird.org/checklist/S65498196

Here are some of the characteristics under discussion-- and my personal conclusion: 
1) dark wing panel favors Least -- in Kirk's pics, yes, but in others, not so much. I think this is a function of lighting and reflection and not that conclusive to me.
2) "whit" call to the ear and sonogram favors Least -- to some; personally, I find this inconclusive and subject to the vagaries of recording equipment, humidity, proximity, etc. It's a very close call. 
3) primary extension and tail length-- I tried to evaluate this looking at photos of this bird and lots of photos of Dusky and Least on line and found the exercise difficult due to differences in posture and angle; no conclusion. 
4) pale lores are fine for Least-- I've always liked this for Dusky, but did not realize that Least often shows it too. 
5) bill color, with darkness on the lower mandible, is okay for Least (and of course fine for Dusky); I did not realize this and probably used this initially to exclude Least from consideration. Apparently, it's fine and there are plenty of pics online with similar bill coloration.
6) bill shape-- this was the clincher for me; it's clearly short and wide, not long and narrow. 

For bill shape comparison, here's a Dusky currently being seen in New Mexico: https://ebird.org/checklist/S77970990
This bird is also very yellow, though I'm not sure what to make of that. 

There are also Least Flycatchers (or Least/Dusky debates?) regarding the current SF and Solano birds. To me, these both seem like Least as well, and very similar to the Davis bird. 

Steve Hampton
Davis, CA

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