Date: 12/4/25 5:33 pm From: Eric DeFonso <bay.wren...> Subject: Re: [cobirds] Bushtit Range Expansion
The RMADC data for Bushtits that I just briefly looked up is roughly in
line with this, showing steady and sometimes significant uptrends in
springtime populations. See the attached screenshot that shows the change
of Bushtit numbers for three shown strata (regions) measured over 16 years,
with year-over-year average increases in density of 7-10% in just the
"lowland" parts of Colorado. The site has data for a number of other
surveyed regions too, I just wanted to highlight the ones that are where
many of us in the Front Range are.
[image: Bushtits-RMADC.png]
Eric
-------
Eric DeFonso
Boulder County, CO
On Thu, Dec 4, 2025 at 4:19 PM Bill Schmoker <bill.schmoker...>
wrote:
> Hi Virginia- I was already digging around a little in the Boulder CBC
> archives in preparation for this year's count and thought I'd look back to
> see what our Bushtit situation has been for the last 20 years. I wonder if
> a CO-wide CBC picture could also be produced but haven't looked into that.
> Anyway, here's what we've had on the count since 2004:
> 2004: 8 (in 1 territory)
> 2005: 4 (feeder watcher)
> 2006: 20 (in 1 territory)
> 2007: 7 (1)
> 2008: 19 (4)
> 2009: 46 (2)
> 2010: 58 (3)
> 2011: 67 (2)
> 2012: 96 (6)
> 2013: 8 (1)
> 2014: 86 (7)
> 2015: 110 (4)
> 2016: 27 (5)
> 2017: 163 (9)
> 2018: 174 (10)
> 2019: 92 (6)
> 2020: 135 (8)
> 2021: 146 (9)
> 2022: 178 (10)
> 2023: 142 (11)
> 2024: 173 (7)
>
> So definitely the expected ups and downs but overall I see a pretty strong
> increase both in numbers of birds and in numbers of territories reporting
> Bushtits in our last 20 counts. I suspect that our earlier counts would
> show even more Bushtit paucity.
>
> -Bill Schmoker, Longmont
>
> On Thu, Dec 4, 2025 at 2:25 PM Virginia Holman <
> <virginiaholmanwrites...> wrote:
>
>> Hi,
>>
>> Are there any studies/reports re: the Bushtit range expansion in Colorado
>> in the last 10-15 years?
>>
>> I'm coming across significant anecdotal information from longtime birders
>> in the region, but nothing formal/science-based yet.
>>
>> Thanks for any guidance.
>>
>> Virginia Holman
>>
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