Hi All,
A few weeks ago, I posted a query to the list, noting that this year's
Henslow's Sparrow at Shawangunk is singing a different song compared to the
single song recorded by multiple observers last year, and wondering if that
was enough of an indication that this year's bird is a different
individual.  That post did not really elicit much interest, based on the
little feedback I received.

Since then, I wrote to a few people directly, including Nathan Pieplow,
whose book, "Peterson Field Guide to Bird Sounds of Eastern North America",
was published last year. Am including my direct query to him. Nathan agrees
that this year's bird is almost certainly a different individual, and he
gave me permission to post his reply, which you will see below.

For those interested, the screen shot of the spectrograms that I sent to
him is now online on my website, in this gallery. You can see from the
screen shot that the first four spectrograms show a "Mi-Re-Do" sequence of
notes, and they are all from this year's bird. The remaining spectrograms
show a "Mi-Do-Re" type sequence of notes. Both three syllable "songs", just
a different sequence of sounds.

https://www.birdsiviews.com/Henslows-Sparrow-Shawangunk-Grasslands/

If you want to see and play back the entire eBird collection of
spectrograms and audio files for both Shawangunk birds, the link is here:

https://ebird.org/media/catalog?taxonCode=henspa&mediaType=a&region=Ulster,%20New%20York,%20United%20States%20(US)&regionCode=US-NY-111&q=Henslow%27s%20Sparrow%20-%20Ammodramus%20henslowii

Nathan's reply and my query to him follow here.

--------------

Karen,

Thanks for the email! I'm very glad you like my book. We need to get more
people using it!

I'm about as certain as I can be that the 2018 bird is a different
individual than the 2017 bird. Here's why:

   - Henslow's is a poorly studied species. But in the research for my
   book, I never found a documented case of an individual Henslow's switching
   songtypes on a recording.
   - You've got a pretty good sample size of recordings here. I went
   through all the 2018 recordings and every rendition is identical. I didn't
   go through all the 2017 recordings but in my sample, they were all
   identical to each other and different from the 2018 bird.
   - All the 2017 and 2018 recordings in your sample are stereotyped, not
   plastic. This basically ensures the recordings come from adult birds. It
   has been shown in many passerine species that once birds are adults, they
   cannot learn new songs. A few birds have been shown to break this rule
   (like Northern Mockingbird), but it would be a surprise for Henslow's
   Sparrow.
   - The 2017 and 2018 songs differ in many details -- one is not merely a
   truncation of the other.

This is actually a pretty good test case for the number of songtypes per
individual Henslow's Sparrow. If birders visit the same bird many times
over the course of a season and never document any song variation, it's
very good evidence that each individual has a single songtype. Plus, it
happens to fit with the little we know about song in Henslow's, and a great
deal that we know about song in passerines in general.

So, I'd say you have a new bird this year.


Nathan

On Thu, Jun 14, 2018 at 3:59 AM, Karen Fung <easternblueb...@gmail.com>
wrote:

> Dear Nathan,
> I very much enjoyed your presentation at the Linnaean Society (NY) last
> year, and bought your book as soon as it came out.  I grew up playing the
> piano as a hobby, so am used to seeing sounds presented in visual form.
> Spectrograms are a great aid in learning bird song!
>
> Anyway, I'm writing to hopefully get your thoughts on whether you think
> the male Henslow's Sparrow that is currently singing at Shawangunk
> Grasslands NWR (NY: Ulster County) is a different bird from last year's
> since its spectrogram is slightly different.  See below for part of an
> email that I sent to local birders.  Was told that Henslow's hasn't nested
> at Shawungunk in maybe 30 years, and that last year's sighting was the
> first one documented in recent memory.  That alone made some folks think
> that the current bird had to be the same one as last year's due to its
> rarity.  Last year it was around for maybe ten days, singing incessantly.
> This year it also sings non-stop, but the sequence of notes is different.
> This year it has a mate, so could it be singing a different song just based
> on that fact?  Your book seemed to indicate that Henslow's only has one
> song in its repertoire.. but could it have modulated its song between
> seasons?.  Some birders agree that it is likely to be a different bird,
> based on its different song, plus its plumage appears to be paler this year
> (but I'm not sure how to evaluate plumage if the bird has molted).
>
> Any thoughts would be appreciated.  The attached screen shot was taken a
> few days ago.  The link to the eBird data for the audio files is below.
>
> Best Wishes,
> Karen Fung
> Manhattan
>

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