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Getting Started with Bluebirds
Over the
years, land has been cleared for housing and industrial developments,
shopping malls, highways, and cropland; many old trees have been cut down
for firewood. Wooden fence posts that provided nesting cavities have now
been replaced with metal posts. With modernization, the supply of natural
nesting cavities for bluebirds and other native cavity nesters has been
greatly reduced.
Compounding the problem of habitat loss has been the introduction into North
America of two imported species - the House Sparrow and the European
Starling. Both starlings and sparrows are cavity nesters, and both are very
aggressive. House Sparrows are small enough to enter any hole that a
bluebird can, and are so aggressive that they will chase away the more timid
bluebird. Starlings can be excluded from bluebird boxes by using the correct
size entrance hole, but will out-compete bluebirds for woodpecker holes and
other natural nesting cavities.
During the summer, bluebirds feed mainly on insects. In the winter,
bluebirds depend on many kinds of wild berries for their food supply.
However, the supply of wild berries has also decreased over the years. The
few berries that remain are often stripped quickly by large flocks of
starlings.
Even though the bluebird population has greatly decreased, the future
can still be promising for them. The most important step we can take to help
bring back the bluebird is to provide nesting sites by setting out a
bluebird box or starting a bluebird trail. A bluebird trail is a series of
bluebird boxes placed along a prescribed route. In areas where nesting boxes
have been put up in suitable habitat, bluebird populations are increasing.
Bluebirding is a great environmental, hands-on project that people of all
ages can enjoy. By following the instructions below, chances are good that
you will be able to attract and enjoy bluebirds.
THE BLUEBIRD
BOX
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A good
bluebird box should be well ventilated, watertight, have drainage holes,
be easy to monitor, and easy to clean.
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Cedar
and redwood are ideal, although plywood and other types of wood can be
used. Boxes can be painted or stained if a light color is used.
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Treated
lumber should not be used because of its toxic content.
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A
bluebird box should never have a perch. Sparrows and wrens are attracted
to perches.
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Boxes
for Eastern Bluebirds should have a round entrance hole of 1 1/2";
Mountain Bluebirds need an entrance hole of 1 9/16"; Western Bluebirds
will use a 1 1/2" hole, but a 1 9/16" hole should be used where the
Western & Mountain Bluebird ranges overlap.
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Oval
holes should measure 1 3/8" x 2 1/4" for the Eastern Bluebird.
MOUNTING THE
BLUEBIRD BOX
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Smooth
round pipe is probably the best and simplest mounting system to use --
3/4" electrical conduit works well, but any smooth scrap round pipe will
also work.
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Coating
the pole with grease will also help to keep predators off the box.
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Hardware
cloth placed under a box helps to prevent snake predation.
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Unless
your trail is in an area where raccoons are not present, avoid mounting
bluebird boxes on a fence line or on trees. Raccoons are known to walk
fence lines and may find your boxes.
SETTING UP A
BLUEBIRD TRAIL
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Habitat
is the key factor to consider when setting up a bluebird trail. Open
rural country with scattered trees and low or sparse ground cover is
best. Suitable habitat should include perch sites, such as a fence line,
wires, or tree branches where bluebirds may perch to search for food.
Look for these when you are selecting a location for your nesting boxes.
If bluebirds do not like the habitat, they probably will not use your
boxes.
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Pastureland, acreages, parks away from human traffic, and mowed areas
such as cemeteries, golf courses are all good locations for a bluebird
trail (provided pesticides are not used).
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Avoid
brushy and heavily wooded areas -- this is the habitat of the House
Wren.
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Avoid
areas where the House Sparrow is abundant (i.e. farmsteads and
feedlots).
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Avoid
areas of heavy pesticide use.
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Mount
nesting boxes so the entrance hole is approximately five feet above the
ground. If possible, face the box away from prevailing winds and facing
towards a tree or shrub which is within 100 feet of the box. Trees and
shrubs provide a landing spot for the young bluebirds when they first
leave the box. This will keep them off the ground, away from predators.
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Nesting
density for all three species of bluebirds is dependent on many factors.
Some of these factors include population density, habitat suitability,
individual tolerance levels, visibility between boxes, the number of
cavities available, weather, and the level of competition from other
species (especially Tree Swallows, or, in the west, Violet Green
Swallows). It is therefore impossible to predetermine the optimal
spacing for any given area. The following distances are given as general
guidelines only; contact your local bluebird
affiliate organization to find out what they recommend, and
experiment by adjusting the distances between your own boxes until you
have established ideal spacing for your particular location. In many
cases, bluebirds have been observed nesting closer than the distances
recommended. However, it is better to start a bluebird trail with boxes
placed too far apart than too close together.
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Western Bluebirds - approximately 100 yards
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Eastern Bluebirds - 125 to 150 yards
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Mountain Bluebirds - 200 to 300 yards
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Boxes
can be mounted in pairs in areas where Tree Swallows are abundant. When
paired, boxes should be mounted 5 to 25 feet apart. This provides
nesting sites for both species and helps to prevent competition between
them. Different species of birds usually do not mind nesting close to
each other.
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Bluebirds rarely nest in cities. It is possible, but uncommon, for
bluebirds to nest along the outer edges of cities or in small towns.
Bluebirds generally prefer rural areas.
MONITORING A
BLUEBIRD TRAIL
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Do not
put up a bluebird box if you do not plan to monitor it. Check your
bluebird boxes at least once a week during the nesting season, until
chicks are close to fledging.
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Do not
open the box after nestlings are 12 to 14 days old. Doing so could
result in the nestlings leaving the box before they are able to fly,
greatly reducing their chance of survival.
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Always
remove House Sparrow nests immediately.
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Have
your bluebird boxes in place by mid-March when the bluebirds return from
their winter migration and are looking for nesting sites. However, boxes
may also be put up later in the nesting season.
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Bluebirds usually nest in late March or early April, depending on
weather conditions. In southern states, where bluebirds reside year
round, nesting may occur earlier.
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Bluebirds usually have two broods per season, but three broods are
possible.
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Recognize a bluebird nest -- It is a cup-shaped nest that is usually
made up of 100% woven grass. Pine needles may be used.
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Bluebirds usually lay 4 to 5 light blue eggs, but may lay as many as 6
or 7. A small percentage of their eggs may be white.
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The
incubation period for bluebird eggs is 12 to 14 days.
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Nestlings remain in the nest 18 to 21 days before they fledge.
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Remove
bluebird nests and those of other birds as soon as the young birds have
fledged.
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Keep
records of the activity on your bluebird trail. This information is
valuable to the North American Bluebird Society (NABS), a non-profit
organization, which compiles data on bluebird populations in North
America. Annual Nesting Report Forms are available from NABS.
Please don't be discouraged if your nesting boxes are not used the first year. If
bluebirds are not common in your area, it may take them a few seasons to
find your new box. Bluebirds generally return to the same area each year.
Bluebird trails have been an extremely effective method of reestablishing
the bluebird populations across North America.
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