Empidonax Flycatcher, Nanjizal Valley, Cornwall

[Hotspur]

A Willow or Alder Flycatcher has been found at Nanjizal - how do you seperate these two species?

[AndyB]

Hi James, call is a good feature - here's a thread that discussed it a little:
http://www.surfbirds.com/forum/showthread.php?t=3999
Look forward to seeing some photos!

[Richard Guthrie]

Whoa, there;

I would urge caution when trying to pin down either of these two species(?).

I admit that I have a tin ear, but even while with birders with very acute hearing skills, separating these two (?) species is difficult even in the best of circumstances.

A recording of the call might be useful.

Perhaps you might try to elicit some playback response from this individual. That technique has worked on some western Empids here in the eastern North America. However, even with a song on territory, the two are a tough ID for most birders.

Good Luck and have fun!

Richard

[Frigatenerd]

Without a singing or calling bird, or unless the bird is caught to check wing formula, there is too much overlap in all visible features to reliably separate the two in the field on plumage alone.

Frigatenerd

[AndyB]

Catching it may be the only way to nail the ID. Presumably, the Bosistow group found this bird and there's usually a lot of nets down that valley in Oct'.

[MichaelF]

If they're so difficult to identify, how do they tell each other apart to avoid interbreeding?

[Richard Guthrie]

The flycatchers know their songs....most of the time. With all the confusion, who knows if they get it wrong now and then.

Regarding wing formulas, even in the hand, there is much difficulty separating the two species. Banders (ringers) here report individuals as "Traills" Flycatchers - which was the name of the species (?) before they were split; unless the individual were to be well within the safe zone of extreme measurements considering multiple factors. These factors include bill color, wing formula, primary feather emargination, bill length and width with overlaps in measurements because of sexual variations. To add to the confusion, there's the issue of "eastern" vs. "western" Willow Flycatchers.

For further discussion, refer to Pyle; 1997; Identification of North American Birds - Part 1; Slate Creek Press; pgs 218-228.

[AndyB]

some photos here now:
http://www.cornwall-birding.co.uk/latest-birding-news/wednesday-8th-october-2008-cornwall-bird-reports/

[Jeffrey Offermann]

By Voice, unfortunately. They tend not to vocalize in autumn very much. Being sub-oscine passerines, they do not learn their "song" but it is hard-wired, so it is a solid mark of the species...if you hear it. Otherwise, Alder averages greener-backed, slightly shorter billed, a tiny bit longer-winged. Most of these parameters can only be judged in-hand.

Best!

Jeff

[Cin-Ty]

Hi there. Great find! This one's really tough. I have still trouble with Traill's even though I see Willows and Alders every year here in Texas.

Here are some of my thoughts, which may or may not be useful.

In general, at least to me, Alder seems to be a crispier looking bird than Willow. The cap tends to be darker, the wingbars tends to be more contrasty (I think the wingbar thing is mentioned in one of Pyle's articles), and the eye-ring tends to be more prominent. Alder's also have slightly shorter bills than Willows (Hussell's work). In this regard, the bird in question seems to lean toward Alder. Of course, the variation in these features is so much that who really can be sure.

There may be some differences in gestalt. I have a feeling that Alders tend to look big-headed (and round-headed) and thick-necked. They kind of don't have much of neck to me, whereas Willow has a proportionately smaller head (often more crested) and a more noticeable neck (I'm probably not conveying this very clearly). Also, Alder seems to hold its tail downward a little more than Willow (which leans toward the pewee look). the bird in question, looks more like Alder in this regard.

Anyway, these features are so subtle that I wouldn't make a firm ID based on just these photos.

For what it's worth... according to Eubanks et al. (who is basing a lot from work by Dittmann and Cardiff in Louisiana), here along the gulf coast and texas, Willows pass through in advance of Alder and are mostly gone by the first week of september. Alders still pass through in late september.

If some measurements could be made on this bird, that would help. There are some papers on this topic by Pyle, Hussell, Phillips and others to name a few.

my 2 cents worth
cin-ty lee, houston, tx

[Bobolink44]

Hi Cin-Ty, is it possible to age these flycatchers eg pale white wingbars with no pale primary tips might suggest it's an adult?

Interesting, the notes about gestalt as browsing the hundreds of photos out there do seem to show a lot of short-billed stout-necked looking Alders (http://www.flickr.com/photos/93519387@N00/95358718/in/set-72057594086538969/) compared to the longer-billed more slender looking Willows (http://www.flickr.com/photos/wildpabirds/878348851/in/photostream/) but as you say must be so much overlap. But maybe these features just help to start you off in a direction.

I'm also interested in this article from Cape May Bird Obs that mentions these features and also implies call is a pretty reliable indicator too:

http://www.birdcapemay.org/tigrina/2007/quiz_1007.shtml

[Joe Ray]

If anyone is going down to Cornwall on Saturday and has a space (which they would be happy to fill with a young lad from Devon), could they please send me a PM. Could meet at Exeter sevices, at junction 31 where the M5 meets the A30/A38.

Cheers
Joe

[Johnny X]

I notice that there is a suggestion of Acadian Flycatcher over at http://www.cornwall-birding.co.uk/.

Does anyone have any thoughts on this?

Edit: Trapped and id'd as 1st W Alder according to birdguides...

[AndyB]

Acadian has longer primary projection compared to Brian Field's top photo of the Nanjizal bird:
http://www.roysephotos.com/AlderFlycatcher.html
http://www.roysephotos.com/AcadianFlycatcher.html

[forktail]

Trapped and confirmed as an Alder

Norfolk should be quiet on Sat morning then...

which will be nice

Tim

[Richard Guthrie]

Good Job.

Nice to be able to confirm the ID!

Was the bird ringed?

Richard

[MichaelF]

If anyone is going down to Cornwall on Saturday and has a space ...
Norfolk should be quiet on Sat morning then...
No such luck . . . looks like it's gone . . .

[Richard Guthrie]

Let's hope it's not belly-up in some university drawer.

[Colin Key]

No such luck . . . looks like it's gone . . .

What else can you expect when it has been molested by these bloody "bird fondlers"!! :realmad:

Colin

[MichaelF]

Let's hope it's not belly-up in some university drawer.
That wouldn't happen in Britain.

More likely inside a Sparrowhawk, I'd think.

[Richard Guthrie]

More likely inside a Sparrowhawk...

That's exactly what happened to New York State's first Hammond's Flycatcher (another Empid). With about a dozen watchers witnessing, a Merlin swooped down and snagged the flycatcher. That was before I was able to get down to the barrier island site where it had been found.

[MichaelF]

I guess that's what's known as Empathy.

[AndyB]

Video story on BBC website:
http://news.bbc.co.uk/2/hi/uk_news/england/cornwall/7662371.stm
There's been a couple of annoyed commenters on Birdguides that day after bird was trapped, it disappeared. But I guess there would be no way to know for sure the bird's identity...

[Bobolink44]

Check out the video here:
http://surfbirds.com/video2/view_video.php?viewkey=a72e8ac0117e74ad46f3