Date: 12/3/25 8:14 am From: 'John Malenich' via Colorado Birds <cobirds...> Subject: Re: [cobirds] Nashville warbler, Northern Parula, and Chestnut sided warbler....
I’m also quite curious if anyone has any thoughts on the underpinnings of
this bouquet of eastern warblers that have been inhabiting Boulder Creek
for the past few weeks. There have been 6 different
species--Chestnut-sided, No. Parula, Tennessee, Pine, Orange-crowned &
Nashville—holed up in this location for some time now. None of them choose
to leave with this past weekend’s cold snap into the low teens (which I
expected likely would happen). We’ll see what comes of today’s snow storm.
But this has had me pondering how this group might of all come
together. We’re these birds all migrating together as a mixed flock and
came to this location together due to the food resources they found
here? Or did they separately get off course and stumble upon this
Aphid-rich spot? Would such a coincidence be possible? All six of these
birds are well out-of-range, considerably off their typical migration
route, and quite delayed in their travels south. Are they sticking around
so long because they can’t get enough food and put on enough fat to fuel
the next leg of their journey south or is the eating so good they just
don’t want to leave? Obviously, I know we likely cannot know with any real
certainty how this came to be, but I’d love to hear what thoughts folks may
have about gathering’s origins.
John Malenich
Boulder, CO
On Tuesday, December 2, 2025 at 5:33:50 PM UTC-7 DAVID A LEATHERMAN wrote:
> John et al,
> I visited this area with friends on Black Friday. When in the trees, I
> think these insectivores are mostly getting APHIDS! Probably still a few
> alive but mostly I suspect the birds are getting cadavers. Aphids are high
> in sugars and would be highly sought after at this time of year for
> sustenance and migratory fuel. The birds might also be getting aphid
> predators like green and brown lacewings, maybe some midges when near the
> creek.
>
> On a related note, the next "The Hungry Bird" article in press (published
> in "Colorado Birds", the publication of the Colorado Field Ornithologists)
> is about painted maple aphids in one sugar maple in Fort Collins and the
> assortment of birds they attracted this fall.
>
> Dave Leatherman
> Fort Collins
>
>
> ------------------------------
> *From:* <cob......> <cob......> on behalf of
> John Tumasonis <snake......>
> *Sent:* Tuesday, December 2, 2025 3:20 PM
> *To:* Colorado Birds <cob......>
> *Subject:* [cobirds] Nashville warbler, Northern Parula, and Chestnut
> sided warbler....
>
> All:
> I bit the bullet and decided to check out the warblers near
> Boulder High today (12-02-25). I found three of the five species reported
> near the 17th Street and bikeway intersection. Several other birders had
> seen 4 of 5 species, before I arrived there. Here are a few things I noted:
>
> 1) These warblers are keeping close in loose congregations - if you see
> one species, you'll probably see several others.
>
> 2) Nearby flocks of red-breasted nuthatches, juncos, house finches, and
> bushtits may or may not be associated with the warblers.
>
> 3) The warblers I saw a feeding at heights of 12 to 40 feet up in all
> different kinds of trees, such as, willows, ash, oak, and cottonwood.
>
> 4) Almost all the trees being foraged on had some leaves - either
> desiccated, or turning yellow to brown. Gleaning (something) from both
> leaves and branches.
>
> 5) The warblers don't just "disappear" - they are foraging on both sides
> of the creek and upslope into brush onto CU campus properties, and Boulder
> High properties. They are also moving up and down the creek drainage.
>
> 6) Reports suggest they are foraging at all times of day: 8, 9, 11, and
> 12 and afternoon at 3 and 4 pm. They appear very hungry and are always
> in motion.
>
> If trying to take photos I would suggest 200 to 400 mm lens, with high
> burst speeds.
>
> And then the big questions: Why are these birds congregating is this
> location at this time of year? Will they continue through the next cold
> front coming on Wednesday? And what the heck are they eating?
>
> Thoughts?
>
> John T (Tumasonis), Broomfield CO
> "I'm not a real birder. I only pretend to be one on CoBirds."
>
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