The Englewood Water Treatment facility adds a lot of warm, if often smelly water, about half way between Dartmouth and Evans Ave. where Grant Frontier Park is located. I looked in the Florida toward Evans area for ducks earlier in December and was quite disheartened by the lack of them. I suspect the recent freezing of the lakes in the area might be a factor in the present situation.
Nancy Stocker
"Joey Kellner" <vireo1@comcast.net>: Jan 05 08:46PM -0700
I have all the data compiled and it looks to have been a good count with a
number of lingering songbirds and a movement of waterbirds as the lakes up
north are FINALLY freezing up.
The Denver CBC was held on Saturday, December 18th with 118 observers in 35
parties and one feeder watcher. The number of participants was down this
year, likely due to covid concerns. Even with the lower number of observers
we were able to find 103 species on Count Day and 3 more Count Week birds!
Rare birds for the Denver CBC included, Surf Scoter (2), American White
Pelican (14!), Spotted Sandpiper, House Wren!!, Hermit Thrush as well as
"unusual" birds such as Tundra Swans (2 groups.2 birds, and 6 birds),
Long-tailed Ducks (3 stopped on a lake and took off within minutes),
Double-crested Cormorants, Yellow-bellied Sapsucker, Barrow's Goldeneye, and
Say's Phoebe.
Big "misses" included Prairie Falcon and Horned Lark (count week).
Joey Kellner
Compiler - Denver CBC
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Hugh Kingery <ouzels8@aol.com>: Jan 05 11:43PM
Urling & I surveyed the southern section of the South Platte on the Urban CBC today. A plethora of ducks!
We counted 466 Shovelers, 225 Mallards, and, the best, 160 Buffleheads. 12 duck species. They included one striking male Barrow's Goldeneye, located just south of Florida Ave.
One observation/question. Ducks packed the river from Florida south to Grant Frontier Park; north of Florida we saw only smaller groups. One section to the north had ice across it. So: why the difference?
Could water quality of the river change there?
Or does the water get colder than the ducks prefer?Or does something else affect their preferences?
Hugh Kingery
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Charlie Chase <charlesachase3@gmail.com>: Jan 05 05:43PM -0700
Hey Hugh
Look to the area of the river with all the ducks and see if there is warm
water/or other fluids entering just above that point. There are numerous
stormwater inflows into the Platte along that stretch. I'll do more
research and see what i can find.
You see that in dramatic fashion at the Denver WasteWater Treatment plant
near 64th and York.
That said, as part of our count today, the Arsenal is mostly bone dry and
or was frozen today except a couple of the creeks. We found Common Snipe
and Virginia's Rails in the ditch just west of Lower Derby as we have the
last few years. A lone really cold Great Blue Heron flew into the marsh as
we were leaving.
Cheers
Charlie
On Wed, Jan 5, 2022 at 4:43 PM 'Hugh Kingery' via Colorado Birds <
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Charlie Chase <charlesachase3@gmail.com>: Jan 05 05:47PM -0700
Awesome!! Forensic CBC's.
On Wed, Jan 5, 2022 at 5:43 PM Charlie Chase <charlesachase3@gmail.com>
wrote:
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Mitchell Bailey <mitchellbailey.civil@gmail.com>: Jan 06 02:04AM +0100
South Platte Renew (Littleton Englewood Wastewater Treatment Plant)
discharges their treated effluent into the South Platte just upstream from
the Grant Frontier Park. Like Metro Wastewater Plant and the Centennial
Wastewater Treatment Plant, they provide warm water in the winter that can
keep many kinds of birds happy. The Pine Warbler and Northern Parula that
stayed below Chatfield Dam last winter come to mind.
Mitchell Bailey,
Los Angeles County
On Thu, Jan 6, 2022, 12:43 AM 'Hugh Kingery' via Colorado Birds <
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"ouz...@aol.com" <ouzels8@aol.com>: Jan 05 04:31PM -0800
One year on the Pikes Peak CBC we noted turkey tracks on snow that had
fallen that day. Because of tracks on fresh snow we deemed them countable
for that day.
Hugh Kingery
On Tuesday, January 4, 2022 at 10:44:50 AM UTC-7 Douglas Kibbe wrote:
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Charlie Chase <charlesachase3@gmail.com>: Jan 05 05:47PM -0700
Awesome!! Forensic CBC's
On Wed, Jan 5, 2022 at 5:32 PM 'ouz...@aol.com' via Colorado Birds <
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Nathan Pieplow <npieplow@gmail.com>: Jan 05 07:17AM -0700
Thanks to Leon for this excellent question and intriguing photo. When I
first saw the length of the bill in the photo, my immediate thought was
Common Raven. However, that exposed plumage does look pretty white.
When Andrew Spencer and I were putting together our paper on identification
of ravens by nasal bristle length (
https://archive.westernfieldornithologists.org/archive/V50/50(4)-p255-p259.pdf),
we looked at lots of raven specimens in museum collections. The bases of
many of the body feathers, not just those on the throat and neck, are
bright white in Chihuahuan and silvery gray in Common. Sibley illustrates
this difference pretty well. But "silvery gray" can look pretty darn white
under certain field conditions.
Because Leon's photo seemed to show the left-hand bird's bill in good
profile, I attempted to use digital tools to measure the ratio of nasal
bristle length to bill length (see attached image). Following the
methodology of our paper, I measured from the top base of the bill to the
tip, instead of from the gape to the tip. The ratio I measured was 47%. My
method had some built-in fuzziness, so I could be 5% off in either
direction -- meaning this raven's actual ratio is probably between 42% and
52%.
As you can see from the attached figure from our paper, that would place
this raven right in the middle of what's expected for Common Raven, and at
the very low end for Chihuahuan. At least 90% of Chihuahuan Ravens would
have a shorter bill relative to the nasal bristles than the bird in this
photo.
This photo was taken in bright sunlight, as evidenced by the reflection off
the right-hand bird's shoulder feathers, and I think that accounts for why
the left bird's underplumage looks so white. Although I don't think it's
possible to be 100% certain from this photo alone, I think these are
probably both Common Ravens.
Raven identification continues to be more perilous than most people
appreciate, and I am one of those who suspect that the two species may even
hybridize in southeast Colorado, just to make birders' lives more
difficult. Many people assume any raven east of I-25 and south of I-70 is
probably a Chihuahuan, at least in summer, and I am certain that is NOT the
case. Common Ravens are common breeders in the canyons of SE Colorado and
they certainly wander onto the adjacent grasslands at all seasons.
Card-carrying Chihuahuans are also definitely present in SE Colorado, and
lots of birds are difficult or impossible to identify, especially given the
distant views that are the norm in that part of the state. "Raven sp."
should be the default eBird tick in SE Colorado unless good views of the
nasal bristles or the feather base color convince you one way or the other.
There are also vocal differences, but variation makes them tricky to use.
We need more recordings that are accompanied by definitive photos of the
vocalizing bird, in order to untangle that sticky web.
Nathan Pieplow
Boulder
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