South Bay Bird Nesting Box, Chestnut-Backed Chickadee 2021
Poecile rufescens barlowi
The bird nesting box is in a tree in my suburban back yard on the
San Francisco peninsula. Since January, the box has been visited by oak titmice,
chestnut-backed chickadees, and Berwick's wrens.
The chickadees built a nest
and hatched a clutch of 6 eggs. Unfortunately, for unknown reasons, care-taking
by the parents suffered a crisis and the nestlings died on April 29. A pair
of chickadees (probably the same pair) initiated a new late-season nesting attempt
on May 3. Four eggs were laid May 10-13 and hatched May 25-27. The four birds
grew successfully and fledged June 16-17.
Daytime spent bringing in nesting material; nights spent elsewhere
Daytime spent away, nights on nest; 1 egg laid per day before sunrise
Most of day and all of night spent on nest
Most of day and all of night spent on nest; frequent feeding
May 26 - June 13
Frequent feeding and waste removal; rapid growth
Young birds leave the nest
June 16-17: Fledging
The four birds grew up and fledged (left the nest) on June 16 and 17. They will spend
a couple of weeks with their parents and then go off on their own. The parents look
really worn out, but they will molt and grow a new set of feathers in the fall.
May 26 - June 17: Feeding & Growing
During the day, the mom & dad chickadees frequently bring food and remove waste,
about one trip every 5 minutes on average. The nestlings grow rapidly.
Peeping became audible starting June 3. They opened their eyes for the
first time on June 4. They grew enough feathers to
be left alone at night starting June 4.
May 25-27: Hatching
The first and second eggs hatched on May 25, the third on May 26,
and the fourth on May 27.
May 12-27: Incubation
To start incubation, the chickadee mom uncovered the
three eggs, built a fluffy "cup" to contain them, and began spending most of her
time on the nest, leaving occasionally
to eat and drink. She no longer hides the eggs under fluff when she leaves.
She laid the last (fourth) egg on May 13.
Eggs were laid in the mornings of May 10-13. The chickadee mom
stayed away most of the day (until May 12 when incubation began)
and spent nights on the nest.
While away during the day, she kept the eggs hidden under a layer of fluff.
May 3-6: Chickadee builds new nest
The chickadees came back with a new, late-season nesting attempt after the
loss of their brood at the end of April. I can't be sure, but I think this
is the same pair, based on the timing of the nesting attempt in the season.
The second day of nest building,
was the busiest with
more than 300 trips to bring in material. By the next day, the nest
was substantially complete.
The chickadees chose to return to a nesting box on the fence instead of the one
in the tree. Cats and squirrels use this fence as a highway. An
extra-long roof helps prevent predators from reaching into the nesting box from above.
April 27-29: Chickadee nestlings perish after care-taking crisis
This section contains links to disturbing videos
for bird experts who might be
able to determine the cause of the care-taking crisis. Viewer discretion
Something caused the chickadee mom to lash out at one of her nestlings
on the evening of April 27 (see
video at 5:24 PM).
She soon settled down, returned the nestling
to the nest cup, and went back to normal behavior.
The next morning, the mom had a health or behavioral
crisis that caused her to tear out the top layers of the nest, cover the
nestlings, and leave for half a day (see
video at 6:25 AM).
Two nestlings died as a result. That
afternoon, the parents went back to normal care, feeding the remaining
four and removing their waste.
That evening, however, the nestlings were left alone in the nest. By the next
morning, April 29, all had died. The parents came back many times to try to feed them
April 25-27: Chickadee nestlings growing
Amber and Chester are busy feeding their nestlings and
carrying away their waste
during the day. At night, Amber sits on them. Each day they
grow a little.
April 23-24: Chickadee eggs hatch
The eggs started hatching on the morning of April 23. By early afternoon, four
eggs had hatched and both Amber and Chester were feeding them. The remaining two
eggs hatched the next day, April 24
April 10-22: Chickadee incubates eggs
A sixth egg appeared on the morning of April 10. The chickadee mom "Amber" now spends most
of the day on the nest, as well as all of the night (as she has been doing since
April 1). During the day, she occasionally leaves the nest for 5 to 10
minutes, spending time with the chickadee dad "Chester". Upon return to the nest, Chester makes
sure that Amber is safely back in the box. Occasionally he
I made the roof bigger and added some wire mesh to help keep out predators.
April 5-9: Chickadee lays eggs
The first egg became visible on April 6, one month after the start of nest
building. While away from the nest, she kept
the eggs hidden under a blanket of fluff. On the morning of April 7, she
defended her three eggs from an
much to my surprise --
I didn't know we had any snakes in our suburban neighborhood!
On April 9, she arranged her five eggs in the nest cup, surrounded
by fluff, and began incubating them.
April 1-4: Chickadee spends nights on the nest
The chestnut-backed chickadee spent each night on the nest,
entering the box around 7 PM and leaving the next morning around 7 AM.
During the day, it visited the box on several occasions, sometimes sitting
on the nest for 5 or 10 minutes, but spent most of its time
away. A Bewick's wren entered the box several times, resulting
March 21-31: Chickadee adding fluffy materials to nest
The chickadee spent the night on the nest March 20-21.
It visited the nest during the day, sometimes bringing in more
fluffy nesting material.
The Bewick's wren showed up in the afternoon
of the 21st, the first time in 7 days, briefly entering and leaving
the box; and again on the 22nd. The oak titmouse also spent a
brief moment on the entrance hole.
I put up a second nesting box in the yard
to attract the other birds. I'm hoping they will leave the chickadees
alone and let them use the nest they spent so much time and effort building
(600+ trips to bring in nesting material).
March 20: Chickadee occupies nest overnight
The chickadee spent the night in the nest for the first
time, at the spring equinox. It entered the box half an hour before
sundown and left it half an hour before sunrise. A
12-hour video record shows the bird preening and resting curled
up in the nest.
During darkness, the video is in black-and-white
due to infrared illumination from the camera. Like humans,
birds cannot see infrared.
March 14-19: Chickadee completes nest
The chestnut-backed chickadee continued working on the nest on and off.
The nest is complete or nearly so. The
Bewick's wrens entered the box on the 14th but did not return after
learning that the box is taken.
The chickadee returns to the box a few times per day.
March 12-13: Chickadee adds fluffy nesting materials; Bewick's wrens enter
The chestnut-backed chickadee starting adding fluffy materials over the
redwood bark starting on March 12, including grass, white fluff (duck down?),
animal fur, and what appears to be old bottle-brush flower filaments. On March 13,
a pair of Bewick's wrens entered the box on several occasions, settling into
the nest cup as if they had built it themselves. So far, the chickadee and
wrens have not come into direct conflict, as they have been at the box at
different times of day.
March 6-11: Chestnut-backed chickadee builds nest base of redwood bark
A chestnut-backed chickadee started bringing in new nesting material,
thin strips of bark torn from a redwood tree 70 feet (20 m) away. It works
very actively for periods ranging from 10 to 50 minutes, making a round
trip every 1 minute to bring in and place a beakful of bark shreds. There
are 3 to 5 such bursts of activity per day, starting around 8 to 10 AM and
ending mid-day or early afternoon
Cornell's All About Birds: "The female builds
the nest on her own. She makes a bottom layer or foundation of moss
and strips of bark.
The nest's upper layer consists of animal fur woven with strips of
bark, grass, feathers, and sometimes textile fibers. Adults also
use fur to make a thin, warm flap to cover eggs when they leave the
nest. Nest building takes 7 to 8 days."
Number of chickadee trips per day to bring in nesting material
Brief bird visits February 13 to March 6
nest building starts
Feb 27: Chickadee removes a piece of snakeskin
A chestnut-backed chickadee picks up a piece of snakeskin previously
left in the nesting box by Bewick's wren, and throws it away. Does
the chickadee intend to take over the box for nesting?
Feb 16: Chestnut-backed chickadees and Bewick's wrens visit
A pair of chestnut-backed chickadees visited multiple times, spending several
minutes examining the entrance hole from the outside. A pair of
Bewick's wrens visited once, bringing in one tuft of grass.
Feb 12: Oak titmouse enters box and takes a piece of snakeskin
One of a pair of oak titmouse birds enters the box and takes a piece of
snakeskin. This is the first oak titmouse entry since Jan 29. Which pair
of birds will nest in the box, the Bewick's wrens or oak titmice? Or neither?
Chestnut-backed chickadees nested there last year. Since last year, I added the
camera, and two frosted acrylic windows to the sides of the box for better
Feb 11: Bewick's wrens return briefly and remove a sprig
The Bewick's wrens returned briefly on February 11, 10, and 8.
They removed a sprig of grass on the 11th and
added a tuft of lichen on the 10th.
There were no visitors at all on February 9.
Feb 7: Bewick's wren brings snake skin to box
The Bewick's wren returns and places a piece of snake skin. I
didn't know we had snakes in the area! It also repositioned
what appears to be skin from a reptile tail. Earlier in the
morning, it brought another piece of lichen.
Feb 5: Bewick's wren brings lichens into the box
This pair of Bewick's wrens is considering whether to build
a nest. One offers the other a sprig of grass; the other
is reluctant to take it, as if the male is saying "Let's build
a nest" and the female is answering "I'm not ready." Later
in the day, the male started adding lichens and leaves
to the box. The next day, February 6, it
returned, moved some of the items, and left, spending
just a minute in the box.
Bewick's Wren Life History:
"The cup-shaped nest has a base of sticks, grasses, rootlets, leaves, moss, or other plant materials, depending on what the local environment provides. The open cup may be lined with feathers, wool, hair, or plant down, with a final inner lining of snakeskin. The male initiates nest building; both sexes participate. The construction process usually takes less than 8 days, though sometimes it can stall for long periods and require weeks to complete."
Feb 4: Bewick's wren pair returns for another inspection
A Bewick's wren pair returns for another inspection after a 2-day absence.
Feb 2: Bewick's wren pair places nesting materials
A Bewick's wren pair places some dry grass in the nesting box.
says that they nest from mid-April to early August. Are they reserving
the box for later?
Jan 31: Bewick's wren checks out the box
Bewick's wren checks out the nesting box for 15 seconds. It came
back for another brief visit the next day, February 1.
Jan 30: Chestnut-backed chickadee checks out the box
A chestnut-backed chickadee checks out the box. This is the species
that nested in the box in 2020. The brown chestnut color is found
only on the back, not on the sides, from Marin County southward.
Farther up north, the brown color extends down the sides.
Jan 29: Oak titmouse checks out the box
An oak titmouse checks out the bird box and clears out spider webs.
It has a very small crest on its head.
The entrance hole
is 1-1/8 inches in diameter to exclude larger birds such as
Green-Backyard Bird Box Camera
Using the Green-Backyard bird box camera, you can capture, save, and view video using CMS5 software on PC. It uses natural illumination by day and infrared illumination at night.
You can capture live video as it is displayed on the PC and save it to a file on the PC. Alternatively, you can direct the camera to save video on an SD memory card in the camera itself, and later retrieve the video from the card. In either case, you can specify the time ranges in which to capture video.
If you are saving the video to the SD memory card, you can direct the camera to save video clips only when there is motion detected in the camera view. Thus, you can capture bird actions as they occur and skip recording when nothing is happening.
When you first power up the camera, be sure to set the exact time in the camera's clock so that you can easily locate video clips by clock time. The camera's clock does not run when the power is off.
I live-stream the bird box view to YouTube using the free OBS (Open Broadcaster Software) application. OBS allows you to mix multiple images, such as the bird box interior and exterior views, and to individually zoom, crop, and place the respective images. It also lets you mix audio sources, such as from the bird box and local microphone.
Bird Nesting Box Natural Illumination
Natural-light windows in a bird nesting box provide illumination for better webcam videos and might also encourage birds to select the box for nesting.
In this box, each window has a translucent piece of acrylic and a wire mesh. The frosty translucence helps distribute the light more evenly in the box and prevents predators from seeing into the box.
The wire mesh might help birds feel more confident about deciding to nest in the box.
Bird preferences might depend on factors such as the amount of light, the sizes or shapes of the openings, and the bird species. The only way to find out for sure is to do a sufficient number of experiments. One
showed that birds preferred nesting boxes with illumination.
If you have a camera inside the bird box, additional natural illumination improves the quality of daytime videos. In dark boxes that have only the bird access hole for light, the camera must boost the weak CCD image, resulting in optically noisy videos. Furthermore, the image is more susceptible to lens flare from extraneous light shining directly on the lens from the access opening, out of view of the camera.
By bringing in more light, the camera generates a better-quality, lower-noise image, and any lens flare has relatively less impact.