Date: 12/4/25 2:24 pm From: Eric DeFonso <bay.wren...> Subject: Re: [cobirds] Bushtit Range Expansion
Hi Virginia,
The Rocky Mountain Avian Data Center has species reports that you can
search, over the years which the IMBCR project has operated (2008-2025).
IMBCR is the Integrated Monitoring of Bird Conservation Regions, an ongoing
breeding bird study organized by the Bird Conservancy of the Rockies. On
the topic of range expansion in the state, the data may be a bit too low
resolution to observe the more local "infill" of Bushtits in some areas of
interest in the state. But it is easier to note the overall population and
density trends statewide since 2008.
The site takes a little time to figure out how to navigate, but there's a
lot of data there, for any of the expected breeding birds in the state, as
well as for the other regions that IMBCR studies. I worked seasonally with
IMBCR for 10 years, 8 in Colorado.
Eric
-------
Eric DeFonso
Boulder County, CO
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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