Fallout of White-throated Sparrows and Hermit Thrushes, Eastern Boulder County, Oct. 18

196 views
Skip to first unread message

tedfl...@gmail.com

unread,
Oct 18, 2020, 9:26:14 PM10/18/20
to Colorado Birds
Hey, all.

On my ramble earlier today, Sun., Oct. 18, about the Greater Greenlee Ecosystem, eastern Boulder County, I found at least 4 white-throated sparrows and at least 8 hermit thrushes.

I'm sure Bryan Guarente has an explanation...

Ted Floyd
Lafayette, Boulder County

P. s. Like others, I find myself suddenly unable to post photos to COBirds.

Patrick O'Driscoll

unread,
Oct 19, 2020, 12:39:29 AM10/19/20
to tedfl...@gmail.com, Colorado Birds
Very interesting, Ted. Maybe it's spreading:

This morning, Sunday Oct. 18, I had a first eBird record of a White-throated Sparrow in the four Denver City Park hotspots outside of the Denver Zoo.
It was in a loose flock of sparrows, juncos and chickadees that flew over the zoo fence, so it was actually in both places.
And BTW, YOU had the last previous WTSP sighting in the zoo back in February 2016.

image.png
After I got home, about a mile east of the park and just off busy East Colfax Avenue, I had a first-ever Hermit Thrush in my backyard.

Excuse the poor photo quality -- the sparrow was shot through a crack in the cyclone-slats-and-vines fence between the zoo and the park road northeast of Ferril Lake, and the thrush was through my kitchen window. 

image.png

Patrick O'Driscoll
Denver




--
You received this message because you are subscribed to the Google Groups "Colorado Birds" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cobirds+u...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/bb01bdff-3d04-47ef-97df-0d6a24d363c1n%40googlegroups.com.

Charles Hundertmark

unread,
Oct 19, 2020, 9:34:42 AM10/19/20
to Patrick O'Driscoll, tedfl...@gmail.com, Colorado Birds
Something was definitely going on. On the 17th, I took a walk behind my home in Lafayette, a couple of miles north of Waneka/Greenlee. My neighborhood near Heron Lake does not usually produce rare birds. One of the first birds I spotted was a male Black-throated Blue Warbler. Then spotted a Ruby-crowned Kinglet and Hermit Thrush. On the rest of a short walk, a couple more Ruby-crowned Kinglets appeared along with a Brown Creeper and a good number of Audubon’s Warblers.

Later that day and through the 18th, other birders chasing my report of the Black-throated Blue refound that bird but also reported several other interesting migrants including at least one White-throated Sparrow.

Chuck Hundertmark
Lafayette, CO

On Oct 18, 2020, at 10:38 PM, Patrick O'Driscoll <pato...@gmail.com> wrote:

Very interesting, Ted. Maybe it's spreading:

This morning, Sunday Oct. 18, I had a first eBird record of a White-throated Sparrow in the four Denver City Park hotspots outside of the Denver Zoo.
It was in a loose flock of sparrows, juncos and chickadees that flew over the zoo fence, so it was actually in both places.
And BTW, YOU had the last previous WTSP sighting in the zoo back in February 2016.

<image.png>
After I got home, about a mile east of the park and just off busy East Colfax Avenue, I had a first-ever Hermit Thrush in my backyard.

Excuse the poor photo quality -- the sparrow was shot through a crack in the cyclone-slats-and-vines fence between the zoo and the park road northeast of Ferril Lake, and the thrush was through my kitchen window. 

<image.png>

Patrick O'Driscoll
Denver




On Sun, Oct 18, 2020 at 7:26 PM tedfl...@gmail.com <tedfl...@gmail.com> wrote:
Hey, all.

On my ramble earlier today, Sun., Oct. 18, about the Greater Greenlee Ecosystem, eastern Boulder County, I found at least 4 white-throated sparrows and at least 8 hermit thrushes.

I'm sure Bryan Guarente has an explanation...

Ted Floyd
Lafayette, Boulder County

P. s. Like others, I find myself suddenly unable to post photos to COBirds.

--
You received this message because you are subscribed to the Google Groups "Colorado Birds" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cobirds+u...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/bb01bdff-3d04-47ef-97df-0d6a24d363c1n%40googlegroups.com.

--
You received this message because you are subscribed to the Google Groups "Colorado Birds" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cobirds+u...@googlegroups.com.

tedfl...@gmail.com

unread,
Oct 19, 2020, 10:35:42 AM10/19/20
to Colorado Birds
On Sunday, October 18, 2020 at 10:39:29 PM UTC-6 pato... wrote:

This morning, Sunday Oct. 18, I had a first eBird record of a White-throated Sparrow in the four Denver City Park hotspots outside of the Denver Zoo.
It was in a loose flock of sparrows, juncos and chickadees that flew over the zoo fence, so it was actually in both places.
And BTW, YOU had the last previous WTSP sighting in the zoo back in February 2016.

On the occasion of Super Bowl 50, no less!

Protip: The best time to visit the zoo is when the home team is in the Super Bowl. The staff felt so bad for us, they gave us free rein of the entire facility. It was an unforgettable experience, with some pretty amazing birds and wildlife:

https://blog.aba.org/2016/03/birding-at-the-zoo.html

Ted Floyd
Lafayette, Boulder County

P. s. Another protip: Might have to wait a few more years before the home team is in the Super Bowl...



Bryan Guarente

unread,
Oct 19, 2020, 1:54:33 PM10/19/20
to Colorado Birds
Why did we see an influx of birds on this date?
It looks like the frontal passage is the culprit for these birds showing up in CO.  Had a nice cold frontal passage that led to our low-clouds, drizzle, increased humidity, and subdued winds (great for fire suppression).  

Green circle on map is Waneka Lake, Boulder County.  The timing of this map is 6am on Sunday October 18th.

Why White-throated Sparrows (WTSP) and Hermit Thrushes (HETH)?
The maybe more interesting question is why WTSP and HETH?

WTSP Breeding Range: 

HETH Breeding Range: 

Based on the wind origin point from the previous map, it would make some sense that any birds that ended up in CO from this weather pattern would have come from MT.  But maybe a better bet would be to go back in time to when these birds would have originally taken off from the origin point.  This usually starts to happen on the night before right around dusk.  Dusk the night before was ~6pm October 17th.  So here is the map (with Waneka Lake at the green circle) that would help us answer that question:


If you backtrack the winds from Waneka Lake to their origin, you get something much more consistent with WTSP or HETH breeding ranges.  We end up around Great Slave Lake in the Northwest Territories.  Anywhere along that backtracked streamline would be ripe for WTSP or HETH departure from the breeding grounds (I know it isn't breeding season anymore, it was an easier reference point though).  It also makes better sense from a bar chart perspective to get WTSP or HETH instead of something like Blackpoll Warbler, which shares the same origin point, but has already likely finished its migration through Colorado.  

Fun to play with all this logic.  Hope it comes across understandably to most of you.  If there are any questions you would like to pose to me for clarification, I am always open for discussion on this.  Happy to be involved and educate on the topic.  

The next forecasted frontal passage is due for Tuesday at around 6pm (depending on your location in CO), but it will be weak and poorly timed for bird migrations.  Expect some birds to leave on the north winds on Tuesday evening, but I am doubting much replacement of birds in CO from behind that front.  The convergence looks better from this front in IA/IL.  

Thanks for the thought experiment.
Bryan

Bryan Guarente
Meteorologist/Instructional Designer
UCAR/The COMET Program
Boulder, CO


--
You received this message because you are subscribed to the Google Groups "Colorado Birds" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cobirds+u...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/cb5a8d3c-075e-45ca-a711-77b64527889cn%40googlegroups.com.
Reply all
Reply to author
Forward
0 new messages