Re: [nfc-l] Migration 9/23-9/24 - HF Gray-cheeks

[Andrew Albright]

Paul or others - do you have the link to the xeno canto discussion?

Two years ago, we had some discussion here -
http://www.mail-archive.com/nfc-l@cornell.edu/msg00509.html
There is some good information in that thread.

Without reading the xeno canto thread, it seems that there is an inbetween
area of either overlap between the two species and/or a subspecies
(probably Gray-Cheeked) that has the internmediate call.

Lastly, if the estimates of the population sizes are roughly correct
(Bicknell's at 100k and Gray-Cheeked at 12 million), then when in doubt is
safest to assume Gray-Cheeked.

On Wed, Sep 25, 2013 at 6:00 PM, Christopher T. Tessaglia-Hymes <
c...@cornell.edu> wrote:

> Hi Paul,
>
> Thanks for commenting. Your examples are fantastic. All starting abruptly
> and peaking almost at 5kHz. The "candidate" examples I provided were
> peaking between 4.7 and 5.0 kHz; however, it seems, none of them were
> sufficiently outside the range of suspected HF Gray-cheeked Thrush-type
> calls.
>
> I agree, we don't know enough about the nocturnal vocalizations of
> Bicknell's and Gray-cheeked Thrushes to safely rule out some of these HF
> candidate calls away from being Bicknell's or to confidently ID them as
> Bicknell's. We simply don't know how much true overlap there may be,
> especially when considering the individual variation between adults and
> juveniles, and males and females, during fall migration. Spring migration,
> presumably, we would only be considering male and female variations and
> could rule out the variability between adults and juveniles.
>
> Ideally, we would have recording stations located near or on a direct
> flight path South or Southeast of their breeding grounds to collect more
> likely candidates as comparison.
>
> Most of my recorded Gray-cheeked Thrush calls –  a good 95% or more – can
> be safely classified as Gray-cheeked Thrushes, due to their overall
> structure and the lower frequency nature of the calls. The other 5% or
> fewer become more questionable, because of the unknowns between HF
> Gray-cheeked and LF Bicknell's.
>
> I'd feel pretty safe calling a candidate call a Bicknell's, if it was
> above 5kHz and had that characteristic abrupt onset (not just humped or
> arched, as with classic Gray-cheeked calls), plus that relatively longer
> wheezy trailing descent.
>
> Only if we could slap microphones on these birds to record their calls
> during their migrations…!
>
> Other insight or comments are very much welcomed in this discussion.
>
> Thanks!
>
> Sincerely,
> Chris T-H
>
> PS - I had problems opening Paul's files in Raven as mp3's, so opened in
> Audacity and converted to 16-bit WAV files. If desired, I can post them
> individually.
>
>
>  On Sep 25, 2013, at 4:02 PM, pjd...@aol.com wrote:
>
>  Hi Chris,
>
> I'd like to open up a discussion on Bicknell's Thrush calls. There was a
> discussion on xeno-canto recently in which there was some questioning of
> the validity of the nocturnal calls as there is so much variability and
> overlap between Gray-cheeked and Bicknell's daytime calls, more recordings
> of which are now available. That not withstanding, I have yet to see a
> daytime recording of a known Gray-cheeked that matches the Bicknell's
> nocturnal call. Isn't it likely that the Bicknell's call is only one of
> many different calls Bicknell's make at night, but perhaps the only one
> that is definitive? Or perhaps it's a call that Bicknell's uses more than
> Gray-cheeked ie there is a quantitative difference in their calls? There
> was also a suggestion that perhaps they are not truly separate species (so
> perhaps all this is moot).
>
> I recorded several calls last night that match Bicknell's quite well.
> These are the first calls I've recorded so far this season that have that
> appearance, and were several different birds. All others (100s) going back
> to September 15th had been typical lower frequency "buffalo-humped"
> Gray-cheeked. To me, this suggests that there is a certain defined
> population that gives this less common call.
>
> Paul Driver
> Elkins Park PA
>   -Original Message-
> From: Christopher T. Tessaglia-Hymes 
> To: NFC-L 
> Sent: Tue, Sep 24, 2013 11:03 am
> Subject: [nfc-l] Migration 9/23-9/24 - HF Gray-cheeks
>
>  Last night was an enjoyable night. Quite active for Gray-cheeked-type
> thrushes (i.e. there were multiple nice HF candidates in there).
>
> The thrush descent was quite extensive, starting around 5:51am and lasting
> until about 6:15am. The peak was from about 6:06am to 6:15pm. Bulk of the
> vocally actively descending thrushes were Swainson's Thrushes, with a mere
> handful of Gray-cheeked Thrushes toward the beginning.
>
> Several warblers and Rose-breasted Grosbeaks were migrating throughout the
> night, although I didn't take a close look at the warblers (a few
> Ovenbirds, though). A single White-throated Sparrow and a White-crowned
> Sparrow (candidate) were noted.
>
> I've attached the best of the HF 

Re: [nfc-l] Migration 9/23-9/24 - HF Gray-cheeks

[pjdeye]

-Original Message-
 From: pjdeye 
 To: cth4 ; nfc-l 
 Sent: Wed, Sep 25, 2013 4:02 pm
 Subject: Re: [nfc-l] Migration 9/23-9/24 - HF Gray-cheeks


Hi Chris,
 
I'd like to open up a discussion on Bicknell's Thrush calls. There was a 
discussion on xeno-canto recently in which there was some questioning of the 
validity of the nocturnal calls as there is so much variability and overlap 
between Gray-cheeked and Bicknell's daytime calls, more recordings of which are 
now available. That not withstanding, I have yet to see a daytime recording of 
a known Gray-cheeked that matches the Bicknell's nocturnal call. Isn't it 
likely that the Bicknell's call is only one of many different calls Bicknell's 
make at night, but perhaps the only one that is definitive? Or perhaps it's a 
call that Bicknell's uses more than Gray-cheeked ie there is a quantitative 
difference in their calls? There was also a suggestion that perhaps they are 
not truly separate species (so perhaps all this is moot).
 
I recorded several calls last night that match Bicknell's quite well. These are 
the first calls I've recorded so far this season that have that appearance, and 
were several different birds. All others (100s) going back to September 15th 
had been typical lower frequency "buffalo-humped" Gray-cheeked. To me, this 
suggests that there is a certain defined population that gives this less common 
call.
 
Paul Driver
Elkins Park PA

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Re: [nfc-l] Migration 9/23-9/24 - HF Gray-cheeks

[Christopher T. Tessaglia-Hymes]

Hi Paul,

Thanks for commenting. Your examples are fantastic. All starting abruptly and 
peaking almost at 5kHz. The "candidate" examples I provided were peaking 
between 4.7 and 5.0 kHz; however, it seems, none of them were sufficiently 
outside the range of suspected HF Gray-cheeked Thrush-type calls.

I agree, we don't know enough about the nocturnal vocalizations of Bicknell's 
and Gray-cheeked Thrushes to safely rule out some of these HF candidate calls 
away from being Bicknell's or to confidently ID them as Bicknell's. We simply 
don't know how much true overlap there may be, especially when considering the 
individual variation between adults and juveniles, and males and females, 
during fall migration. Spring migration, presumably, we would only be 
considering male and female variations and could rule out the variability 
between adults and juveniles.

Ideally, we would have recording stations located near or on a direct flight 
path South or Southeast of their breeding grounds to collect more likely 
candidates as comparison.

Most of my recorded Gray-cheeked Thrush calls –  a good 95% or more – can be 
safely classified as Gray-cheeked Thrushes, due to their overall structure and 
the lower frequency nature of the calls. The other 5% or fewer become more 
questionable, because of the unknowns between HF Gray-cheeked and LF Bicknell's.

I'd feel pretty safe calling a candidate call a Bicknell's, if it was above 
5kHz and had that characteristic abrupt onset (not just humped or arched, as 
with classic Gray-cheeked calls), plus that relatively longer wheezy trailing 
descent.

Only if we could slap microphones on these birds to record their calls during 
their migrations…!

Other insight or comments are very much welcomed in this discussion.

Thanks!

Sincerely,
Chris T-H

PS - I had problems opening Paul's files in Raven as mp3's, so opened in 
Audacity and converted to 16-bit WAV files. If desired, I can post them 
individually.


On Sep 25, 2013, at 4:02 PM, pjd...@aol.com wrote:

Hi Chris,

I'd like to open up a discussion on Bicknell's Thrush calls. There was a 
discussion on xeno-canto recently in which there was some questioning of the 
validity of the nocturnal calls as there is so much variability and overlap 
between Gray-cheeked and Bicknell's daytime calls, more recordings of which are 
now available. That not withstanding, I have yet to see a daytime recording of 
a known Gray-cheeked that matches the Bicknell's nocturnal call. Isn't it 
likely that the Bicknell's call is only one of many different calls Bicknell's 
make at night, but perhaps the only one that is definitive? Or perhaps it's a 
call that Bicknell's uses more than Gray-cheeked ie there is a quantitative 
difference in their calls? There was also a suggestion that perhaps they are 
not truly separate species (so perhaps all this is moot).

I recorded several calls last night that match Bicknell's quite well. These are 
the first calls I've recorded so far this season that have that appearance, and 
were several different birds. All others (100s) going back to September 15th 
had been typical lower frequency "buffalo-humped" Gray-cheeked. To me, this 
suggests that there is a certain defined population that gives this less common 
call.

Paul Driver
Elkins Park PA
-Original Message-
From: Christopher T. Tessaglia-Hymes mailto:c...@cornell.edu>>
To: NFC-L mailto:nf...@list.cornell.edu>>
Sent: Tue, Sep 24, 2013 11:03 am
Subject: [nfc-l] Migration 9/23-9/24 - HF Gray-cheeks

Last night was an enjoyable night. Quite active for Gray-cheeked-type thrushes 
(i.e. there were multiple nice HF candidates in there).

The thrush descent was quite extensive, starting around 5:51am and lasting 
until about 6:15am. The peak was from about 6:06am to 6:15pm. Bulk of the 
vocally actively descending thrushes were Swainson's Thrushes, with a mere 
handful of Gray-cheeked Thrushes toward the beginning.

Several warblers and Rose-breasted Grosbeaks were migrating throughout the 
night, although I didn't take a close look at the warblers (a few Ovenbirds, 
though). A single White-throated Sparrow and a White-crowned Sparrow 
(candidate) were noted.

I've attached the best of the HF Gray-cheeked Thrushes to this message. None of 
these are perfect for Bicknell's, but interesting non-the-less.

Here in Etna, NY (located about 180 miles, as the Bicknell's flies, to the SW 
of Whiteface Mountain in the Adirondack Mountains) we had NE winds to start the 
night, calming and then becoming East winds for the remainder of the night.

Are there any listeners or night recordists immediately due South or Southeast 
of Bicknell's Thrush breeding ranges? Just curious to know if there are other 
really good examples out there to compare with.

Thanks and good night listening!

Sincerely,
Chris T-H


--
Christopher T. Tessaglia-Hymes
Field Applications Engineer
Bioacoustics Research Program, Cornell Lab of Ornithology
159 

[nfc-l] Etna, NY: Night Migration 9/24-9/25

[Christopher T. Tessaglia-Hymes]

Last night was a good night for Swainson's Thrushes and Gray-cheeked Thrushes. 
There were several small waves throughout the night. The descent was full of 
blinging Swainson's Thrushes and a few screaming Gray-cheeked Thrushes. I heard 
my first migratory Hermit Thrushes of the fall last night as well (5:03am and 
5:47am).

Last thrush was a Gray-cheeked at 6:24am and first Blue Jay was at 6:30am.

Attached is a brief clip of the loudest and densest section of Swainson's (and 
a few distant Gray-cheeked Thrushes) descending at 6:21am.

Sincerely,
Chris T-H

--
Christopher T. Tessaglia-Hymes
Field Applications Engineer
Bioacoustics Research Program, Cornell Lab of Ornithology
159 Sapsucker Woods Road, Ithaca, New York 14850
W: 607-254-2418   M: 607-351-5740   F: 607-254-1132
http://www.birds.cornell.edu/brp

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