Date: 10/18/25 4:58 pm From: Tim Jackson via groups.io <eldoradobirds...> Subject: Re: [centralvalleybirds] [SNMountainBirds] White-Crowned Sparrow Return Dates
FYI, here is a interesting and different perspective on White-crowned
Sparrows in our yard (audio detections over the last two years). I have
a microphone hooked up to a small stationary computer (rasberry-pi
based) running Birdnet (cousin to Merlin). The lower chart shows the
daily detects from October 2023 to October 2025, and you can see the
empty months (early May to late September). The upper chart shows
relative percentage of detects by the hour of the day over this period.
On 9/22/2025 3:18 PM, Timothy Jackson wrote:
> Keep in mind the slight push back could be human error. After all I
> can only check so many times a day. It could be that the first bird
> returned a few days before but it wasn't out in the open during the
> amount of time I spent looking for it that day.
>
> Here is a histogram. The 19th is the most common. Perhaps in another
> 20 years it will resemble more of a bell curve?
>
>
>
> Timothy Jackson
> Shingle Springs, CA
>
> On 9/22/2025 11:49 AM, Sammy Cowell wrote:
>> Very cool data Tim! I went ahead and did a quick plot of your numbers
>> in Excel; ended up with a nice-looking graph! I didn't fit a line to
>> it, but it seems that return dates are being pushed back ever so
>> slightly. Would be interesting to see how/if these numbers change and
>> what that could potentially indicate about the impacts of climate
>> change on migration. Either way, thanks for sharing!
>>
>> image.png
>> Sammy Cowell
>> Valley Springs, CA
>>
>> On Sun, Sep 21, 2025 at 7:52 AM Tim Jackson via groups.io
>> <http://groups.io> <eldoradobirds...> wrote:
>>
>> Hi,
>>
>> We saw White-crowned Sparrows in our yard (Shingle Springs) this
>> morning.
>> Here are the historical return dates for our yard:
>>
>> 2001 - 9/15
>> 2002 - 9/19
>> 2003 - 9/22
>> 2005 - 9/17
>> 2006 - 9/18
>> 2007 - 9/19
>> 2008 - 9/15
>> 2009 - 9/19
>> 2010 - 9/13
>> 2011 - 9/18
>> 2012 - 9/12
>> 2013 - 9/14
>> 2014 - 9/15
>> 2015 - 9/20
>> 2016 - 9/17
>> 2017 - 9/19
>> 2018 - 9/20
>> 2019 - 9/26
>> 2020 - 9/20
>> 2021 - 9/19
>> 2022 - 9/17
>> 2023 - 9/21
>> 2024 - 9/19
>> 2025 - 9/21
>>
>> Tim & Angela Jackson
>> Shingle Springs
>>
>>
>>
>>
>>
>