By Sarah Wibell
Betsy Wagenhauser hosted an informational workshop about bluebirds and walked people around part of her bluebird trail on Saturday, January 26. Wagenhauser’s bluebird trail, which consists of 12 bluebird houses set approximately 100 yards apart from each other, allowed locals to see proper designs and locations for such houses.
Roughly half of all fledgling bluebirds do not survive the first year. However, Wagenhauser says since she started her trail and other people in Madison have also added boxes, she notices bluebirds more than ever.
Wagenhauser fledged 51 bluebirds last year with only nine of her boxes being used by bluebirds. “If I had 51 babies with my houses, imagine what would happen if everyone else put up even one,” she stated. “My dream is for Madison to become the bluebird capitol of the world.”
Details about the best direction the opening of bluebird houses should face – east is most suitable to avoid northern winds – were discussed along with ways to ventilate the boxes. The importance of scoring the inside of the houses to assist fledglings climbing up to the entrance, predator guards, and using a metal conduit to limit predators climbing to the nests was demonstrated. Wagenhauser further explained how to monitor bluebird nests, clean out the boxes after a nest fledges, and update data to Nestwatch.org.
All of the key information discussed was reiterated in a handout that can be viewed on the Morgan County Citizen’s website at www.morgancountycitizen.com. Wagenhauser further recommends www.sialis.org and The Bluebird Monitor’s Guide by Cynthia Berger, Keith Kridler, and Jack Griggs as superb sources for individuals interested in attracting and supporting bluebirds.
How to attract bluebirds to your yard
The easiest way to set up a bluebird house and where to locate
Use electrical conduit pipe ½” diameter. Will have to cut 12’ pole to 8’ and sink in ground about 2’ so that 6’ is
above ground. Attach ½” brackets to back of nest box to attach to pole.
Choose open field or lawn, with scattered trees and low or sparse ground cover. Box should be at least 50’ away
from brush or woods, out in open. Best to face east (to avoid north winds) or north.
Box should be within 15-20’ of branch/tree that is visible from opening for fledglings to see where they can fly to
when they leave the nest.
Bluebirds like to use pine straw and other straw for nesting material. I’ll usually throw some straw at the base of
the nest box to help the bluebirds out.
Bluebird box is:
deep and should have a few scored grooves cut on the inside, underneath the opening so fledglings can grasp
the inside wall and climb up to the nest box opening when they are ready to fledge. (if the box is made of rough-
hewn cedar, sometimes that is enough for the babies to get a foothold and climb.)
1 ½” hole opening
Best not painted (if hardwood can be painted in neutral colors). Never paint the inside!
Rough cedar is best
Has door that opens on side or in front – for monitoring.
Will have screw or lever to keep door securely closed
How to monitor your bluebirds
Blue birds will usually nest 2 or 3 times per season – and once they’ve chosen a mate, they stay
monogamous for the season
They do not like to build over or use old nests, so once the babies have fledged, you will need to clean
the box and remove the old nest. This should be done within a few days of the babies departing.
At the beginning of the season (late Feb/early March), start checking every week or so to look for
nesting activity/nest building.
Once you see some evidence that a nest is being built (straw inside), the you can start checking every 4
to 7 days for activity.
Bluebirds are tolerant of humans, so checking the box is not going to disturb them, especially if you are
fairly quick – like in and out under a minute or 2.
I like to take a picture of the interior every time I check a box just to keep track of the nest progress
and be better able to predict when eggs, once all laid will hatch and then fledge.
FYI – the mama bird won’t start incubating her eggs until she’s laid them all – usually 5 over a 5-day
period. So you can’t start the hatch countdown until all the eggs are laid. Eggs will hatch about 14 days
after incubation starts, and babies will fledge about 17 days after hatching.
Nestwatch.org – great for lots of good information (through Cornell University) and excellent for tracking your own
bluebird data if you sign up and get your own account.
www.sialis.org – the absolute best site for all things bluebird
The Bluebird Monitor’s Guide by Cynthia Berger, Keith Kridler, Jack Griggs. It’s out of print, but you can find a used copy
on the internet – like Amazon.
The information below is taken from the sialis.org website.
(Also see Bottom Line Advice for New Bluebirders and a 4 page Bluebirding Handout )
Until fairly recently, Eastern Bluebirds (Sialia sialis) were uncommon in Connecticut, mainly due to loss of
habitat open space/snags), and competition for nesting sites from introduced species (starlings and house [English]
sparrows). However, bluebirds are coming back. They are fascinating, beautiful birds. You can help increase their
numbers. The keys are:
Learn to recognize nests and eggs. See nesting timetables: typical Eastern | Mountain | Western | Eastern
Bluebird in CT
Put up nestboxes (think location, location, location.)
Control predators and House Sparrows.
Supplement food and water.
Learn to recognize nests and eggs (more photos) – also see chart on relative sizes of eggs.
Bluebird: Neat, cup shaped, woven nest of 100% fine grass or pine needles. Occasionally bits of fur or a few
feathers and rootlets. Fairly deep nest cup. Eggs are powder blue, sometimes white. NOTE: Western Bluebirds will
routinely add ribbons, cellophane, feathers, thin bark and leaves to their nest. Note: Rare open-cup nests were
found in surface-mined lands in KY and on oak limbs in SC.
House Sparrow: Jumble of odds and ends, including coarse grass with seedheads, cloth, white feathers, twigs and
sometimes litter. Tall nest, may have tunnel-like entrance. Eggs are cream, white, gray or greenish, with irregular
Tree Swallow: Nest of grass lined with feathers. May be messy. Flatter cup than bluebirds. Eggs are pure white.
Black-capped Chickadee: Downy nest of moss, fur, and soft plant fibers. Female may cover eggs with moss when
leaving the box. White eggs with brown speckles.
Tufted Titmouse: Downy nest of moss, fur, and soft plant fibers. May have many earwigs living in it. White eggs
with rose/mauve speckles.
House Wren: Messy nest of twigs, occasionally lined with fine fibers or feathers. Males may build unlined eggless
“dummy nests” in nearby boxes to reduce competition. Tiny glossy white eggs, sometimes tinted with pink/buff,
with lots of fine pinkish brown/reddish brown/brown specks that sometimes form a ring on the larger end of the
Build or purchase a nestbox designed specifically for
bluebirds. These boxes are made of unpainted, untreated
3/4″ – 1″ wood or PVC, have an overhanging slanted roof
(2-5″, with a shallow saw kerf (groove) to keep rain from
entering the box), no perch, a round 1.5″ diameter hole
(or 1.375″ x 2.250″ oval hole. Mountain Bluebirds need a
1 9/16″ hole), ventilation, drainage holes, are deep
enough so predators can’t reach in and get to the eggs,
and have a door that opens for cleaning and monitoring
(if rough wood is not used, add kerfs to inside of door to
enable fledglings to climb out). Birds may roost in the
boxes in cold weather, and the ground may be frozen in
February/March when they start house hunting, so put
boxes up in late fall or winter. See plans.
DON’T install nestboxes in brushy and heavily wooded
areas, too close to trees or shrubbery. This
invites House Wren attack.
DON’T install nestboxes within 200 yards of barnyards
where animals are fed, or where House Sparrows are
abundant unless you are willing to actively manage
House Sparrow populations.
DON’T mount boxes on trees or fence lines–they
provide easy access for predators. More info…
DON’T install boxes near where pesticides or
herbicides are used. Don’t use pesticides inside boxes
unless they are approved for caged birds.
DON’T hesitate to destroy House Sparrow
nests and eggs . House Sparrows are non-native
Put up nestboxes in semi-open grassland habitat, such as
mowed meadows, large lawns, cemeteries,
orchards, roadsides, and areas with scattered trees and
short ground cover. Areas with fence lines, some medium
size trees, or telephone lines provide perches for hunting
and nest-guarding. If no native birds use the box for two
years, try a different spot. (Note: Western Bluebirds do
not favor large, open meadows.)
Mount boxes on 8 ft., 3/4″ diameter galvanized pipe,
with the entrance hole 5 ft. off the ground. If away from
prevailing winds, face E/N or NE.
Keep boxes a minimum of 125-150 yards apart. If
nesting bluebirds are harassed by Tree Swallows, or
more than 50% of bluebird trail boxes are occupied by
swallows, set up a second, “paired” box 5-20 ft. from the
first. Boxes that Tree Swallows nest in should have
“kerfs” or grooves (saw marks about 3/4″ apart) or 1.5-
2″ wide x 6″ long plastic screen (gutter guard) stapled
tightly inside below the entrance hole to enable fledglings
Install predator guards to keep snakes, raccoons and
other predators from raiding nests (e.g., a 2-4 ft. long,
8″ diameter stovepipe or PVC pipe sleeve on the pole,
mounted (so it wobbles) just under the box), even if you
don’t have problems the first year of nesting. Losses
without predator protection may run 25-33%.
If squirrels chew the entrance hole to widen it, screw
a metal hole guard(available from birding stores) or a
1.5″ thick block of hardwood with a 1.5″ entrance hole
over the damaged hole, or replace the front part of the
Try attaching strands of 10 lb. fishing line to boxes and
feeders to scare House Sparrows. Sparrow
spookers made of mylar are VERY effective – put them up
AFTER the first egg is laid and remove after fledgling.
Plant native trees, shrubs, and vines that provide fall and
winter food for bluebirds. Consider offering mealworms.
Monitor boxes at least once a week to check on progress
and control House Sparrows, paperwasps , blow flies, etc.
You can remove eggs that have not hatched 5 days after
last egg hatched.
Bluebirds like a clean box. Remove bluebird nests as
soon as the young fledge, or if nesting fails, to encourage
another brood. Put nests in the trash to avoid attracting
predators. If mice nest in the boxes over the winter,
clean them out in February. See instructions.
Replace or repair any split, rotten, or broken pieces on
boxes that could let rain in and chill nestlings.
Be patient! See more tips. And be prepared to become
possessed by these captivating birds.
invasive pests, and are not protected by law. You
might think they’re cute (some bluebirders refer to
them as “rats with wings”), but they will attack and kill
adult bluebirds (sometimes trapping them in the
nestbox), and destroy eggs and young. House
Sparrow nests, eggs, young, and adults may be legally
removed or humanely destroyed under U.S. federal
law. It is better to have no box at all than to
allow House Sparrows to reproduce in one.
DON’T remove active nests of any native bird,
including Tree Swallow, Tufted Titmouse, or chickadee
nests. It is illegal to disturb an active nest of any bird
except House Sparrows, starlings and pigeons, which
are not protected. Empty House Wren nests can be
DON’T feed corn, bread, milo, or millet in bird feeders,
as this attracts House Sparrows. Stick with black
sunflower seed, thistle (nyjer/niger/nyger) and fruit.
Or try a Magic Halo.
DON’T worry that monitoring will make the parents
desert the nest. Bluebirds tolerate human
presence. Touching the nest will not make the birds
leave–your mother just told you that to keep you from
harassing them. Most birds don’t have a good sense of
DON’T monitor more often than 2x/week, or in early
morning (as eggs are usually laid 1-2 hours after
sunrise)/evening/during bad weather.
DON’T touch eggs while monitoring. Some, especially
chickadee eggs, are very fragile. Also oil from hands
could inhibit hatching.
DON’T open the boxes once the birds are 12-14 days
old. (Their eyes are fully open when they are 8-11
days old. Parents may just dip their heads into the box
hole to feed the young at this age). It can cause young
to fall or hop out of the nestbox before they are
capable of flying, reducing their chances for survival.
DON’T paint boxes a dark color. (Light colors on the
EXTERIOR only are acceptable.) If desired to preserve
wood, coat exterior only with linseed oil or a product
like SUPERDECK (Coastal Gray), and allow to dry
thoroughly before box will be used.
DON’T assume the nest is abandoned. During egg
laying, adults may spend very little time in the box.
On hot days, the female may leave the nest for long
periods of time. The only sure way to know the nest is
abandoned is if neither parent has visited the nest for
four full hours after the young have hatched. If it has
been abandoned, contact alicensed wildlife
rehabilitator (e.g., Joan Fuller 974-3265), the Audubon
Society or the North American Bluebird Society.
DON’T get discouraged if bluebirds don’t nest in your
boxes the first year.
Bluebird Ti metable in Connecticut – see photos of nestling development. Also see general bluebird nesting
timetable and more information on bluebird biologyfor Eastern Bluebirds | Mountain Bluebirds | Western Bluebirds.
Also see typical first egg dates by State.
Scouting: February to Mid-March: Bluebirds start checking out nesting sites. Late arrivals, or previously unpaired
birds may nest as late as July or even August, and some pairs have multiple broods. It’s never too late to put up a
nestbox, as they may be used for a subsequent nesting (see Number of Broods), for roosting, and are also often
checked out in the fall by birds that may return the following spring.
Nest building: 2-6 days.
Egg laying: 5-7 days. Usually laying one per day (skipping a day in cold weather is possible but uncommon), for a
total of 4-7 eggs. Often start egg laying a few days after nest is completed. Egg laying can be delayed (sometimes
for a week or two – 3 weeks is not unheard of) in cold weather, for young parents, or in cases where food is scarce.
In Connecticut, the first egg is generally laid in April. (Earliest reported in CT: First week of March. Latest reported
in August – 3 broods that year. One brood/year is more common in CT.) Later broods tend to have fewer eggs,
and Bluebirds tend to lay more eggs per nest in the north vs. south, but southern birds have a longer nesting
Incubation: 12-14 days. While they may sit on eggs occasionally during the egg laying period, “full-time” regular
incubation doesn’t start until all eggs are laid. They may wait about a week if weather is still cold. They may start
incubating before the clutch is complete in warmer conditions. Hatching failure is highest during warmer conditions.
Hatching: May occur over 24-48 (rarely 72 hours)
Fledging: 16-21 days, typically 17-18. Occasionally a runt will fledge one or even two days later than the others.
When they are first born, they look “a bit like hairy shrimp.” Insect availability may speed up or delay fledging. If
the box is empty in this time frame, the nest is flattened, and there is some fecal material (white) on the walls, it
usually means fledging was successful. Once they leave the nest, bluebirds do not return to it. When the babies are
28 days old, they can fly well. They can feed themselves by Day 30.
Number of Broods: One to four broods per year. Fourth brood attempts may be made in southern climates. The
number of broods probably depends on timing, temperatures, food availability, box availability and the experience
or age of the parents. A subsequent brood may be started within days or weeks of fledging the previous brood. It
may be in the same box or a different box.
If you keep track of dates, you will be able to avoid opening the box after the young are 13 days old, to prevent
premature fledging. At this age, bright blue feathers are evident on males. Also
see www.texasbluebirdsociety.org “Eastern Bluebird Nestling Daily Growth Series” or Pam Ford’s photos to help
determine age. Some studies have shown that 30% of bluebirds return to previous nesting sites the following season