Date: 9/22/25 3:22 pm From: Tim Jackson via groups.io <eldoradobirds...> Subject: Re: [centralvalleybirds] [SNMountainBirds] White-Crowned Sparrow Return Dates
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
>
>
>
>
>
