Date: 2/28/26 8:39 pm From: Chris Conard via groups.io <conardc...> Subject: [centralvalleybirds] Bufferlands portion of the Rio Cosumnes CBC on 29 Dec 2025
Hi folks,
I also typically share the summary of the Bufferlands portion of the Rio
Cosumnes CBC that I send to staff and volunteers.
On Monday, December 29, 2025, a record 20 counters made up of Bufferlands
staff and volunteers participated in the 30th annual Rio Cosumnes Christmas
Bird Count (CBC). The weather was challenging, being cold and foggy for
most of the day. The first couple hours were nearly fruitless. We divided
into five teams, but had limited access on the west side of the property
because of flooding (the water level was at 5.0 ft above sea level with an
attenuated connection to the waters of the Delta). The Bufferlands and the
EchoWater Facility (formerly the Sacramento Regional Wastewater Treatment
Plant) it surrounds is at the northwestern portion of the 15-mile diameter
CBC circle that includes the Cosumnes River Preserve, Stone Lakes National
Wildlife Refuge, western Elk Grove, northwestern Galt, and a portion of
Merritt Island in Yolo County.
We recorded 102 species on the Bufferlands, within a historical range of 90
to 120, and counted 11,443 individual birds, within a historical range of
7,723 to 811,644. We didn’t add any species to our cumulative total of 166
species recorded on the Bufferlands in the count’s 30 years. This is our
lowest species total since 2000, and the lowest since we have been covering
District property west of I-5. We also recorded the fewest number of total
birds since 2000, though that is mostly because we had only 1,336 invasive
European Starlings, down from an average of over 100,000—so our low bird
total isn’t entirely a bad thing. I participated in three other CBCs in the
region this season and all were hampered by fog or rain—it was a rough
patch of weather for surveying birds.
Starting with waterfowl, numbers and diversity were well below average. We
missed Snow Geese, Ross’s Geese, Cackling Geese, as well as Tundra Swans,
and recorded 187 Greater White-fronted Geese. We missed invasive Mute Swans
that we had found the two previous years. Duck numbers and diversity were
disappointing. We missed Canvasback, one of our mascot species, for the
third year in a row, had only three Ring-necked Ducks (150 were seen the
day before), and missed Ruddy Duck. Dabbling duck numbers were also on the
low side and with no surprises, though the two Cinnamon Teal found could
easily have been missed. We found seven Hooded Mergansers and one Common
Merganser; the latter we have missed more often than not in recent years,
while Hoodies have become a staple since 2006. Waterfowl appear to be thin
on the ground in the region. This may be because of widespread flooding
resulting in the birds being more widely but thinly distributed--but that
is only a guess.
After finding our first Wild Turkeys (2) in 2003, numbers ballooned to
nearly 500 by 2019. They have been slowly falling in the last few years,
and were at 201 this year. It will be interesting to see if this is a trend
or a blip. Prior to 2003, we expected at least 100 Ring-necked Pheasants on
count day. Recent totals have been in the single digits, but we missed them
for the first time this year. We found three Virginia Rails and 11
Soras—the latter were quite vocal in the late afternoon. We missed and no
longer expect to find Common Gallinules on the property. Sandhill Cranes
have become regular for more than a decade, and this time we recorded 104.
A single flyby Long-billed Curlew was a nice pickup. We found an impressive
eight Spotted Sandpipers, all in the SSBs (sewer ponds). Five Western
Sandpipers is a nice total for a species recorded for just the sixth time,
but for the fifth year in a row. We only recorded a single gull, a
California Gull. The loafing gull flocks at Black Crown Lake and/or the
SSBs on sunny winter days did not materialize on this cold and foggy one.
Raptors numbers were a bit below average, which is probably best explained
by the cold and foggy day. We found 11 White-tailed Kites, only five
Northern Harriers, and 34 Red-tailed Hawks. Two Bald Eagles, a species that
attempted to nest here last year, accounted for just the second time we
have found the species on the CBC. We recorded three Barn Owls, only four
Great Horned Owls, and a good total of seven Burrowing Owls, especially
considering cold conditions that often keep them hidden. We recorded 13
American Kestrels, two Merlins, and two Peregrine Falcons, but missed
Prairie Falcon. Two Acorn Woodpeckers were a nice surprise (found only four
times), as was a Red-breasted Sapsucker (found only six times).
Yellow-billed Magpies and Loggerhead Shrikes have declined since 2005 when
West Nile virus arrived in our area--we found just 13 magpies and two
shrikes. Two Common Ravens were recorded. This species wasn’t regular in
our area until about a dozen years ago, but we have now found it seven
years in a row.
Western Bluebirds have only been regular on the property since 2014 and we
recorded 39 (one more than last year). We missed Oak Titmouse, a species
that is surprisingly uncommon on the property. We found seven Tree
Swallows, an above-average 214 Bushtits, 78 Ruby-crowned Kinglets, but
missed Golden-crowned Kinglets, found 14 Cedar Waxwings (missed most
years), seven American Robins (missable), and missed Varied Thrush.
Sparrow numbers were mostly below average, but two White-throated Sparrows
were a nice surprise (https://ebird.org/checklist/S291081432). Ten
Orange-crowned Warblers was a good total, though Myrtle Yellow-rumped
Warblers were surprisingly scarce at only four. Audubon’s/unspecified
(presumed Audubon’s) Yellow-rumpeds were reasonably abundant at nearly 300.
A brief aside about species totals and probabilities… Over 30 years, we
have recorded 166 species, and yet the range of species found on a given
count has been between 90 and 120, and 100 to 120 since 2000. There are
only 53 species we have recorded every time, eleven that we have recorded
29 out of 30 times, and five more that we have recorded 28 out of 30 times.
That means that there is considerable variability among the species making
up the totals, yet some stability in the total number of species found each
year. Once we first passed the 100-species threshold in 1999 (with 104), it
seemed unlikely that we would ever fall below it again. And yet, without
quite a few good finds, we could have been in the low 90s. A short list
(14) of very missable species we found include Cinnamon Teal, Common
Merganser, Long-billed Curlew, Dunlin, Western Sandpiper, Bald Eagle,
Merlin, Peregrine Falcon, Acorn Woodpecker, Red-breasted Sapsucker,
Loggerhead Shrike, Tree Swallow, Cedar Waxwing, and White-throated Sparrow.
Somewhat surprising misses included any *Aythya *species diving duck
besides Ring-necked Duck, Ruddy Duck, Ring-necked Pheasant (may be on its
way out regionally), any gull other than the one California Gull we found,
Sharp-shinned Hawk, Great-tailed Grackles, any uncommon wintering
warbler—actually not that many compared to the number of decent pickups.
Thanks to everyone who participated. This 30-year dataset provides a
valuable snapshot of our wintering bird population and is part of the CBC
and Bufferlands tradition. We’ll see what next year brings!
