Nestbox Placement and Mounting at Suitable Sites
Once you've determined that your site is suitable, it is critical to place and space nestboxes properly,
especially given the threats from invasive exotic birds and our own native House Wren. Open, sunny
areas at least 60 m (200 ft) from dense woods or brush,
with a few scattered trees or saplings for perching, are
ideal.
Nestbox Spacing
Space boxes at intervals of about 100 m (300 ft).
If House Wrens are likely to be a problem, be sure the box
is mounted at least 60 m (200 ft) away from a wooded or
brushy area. To reduce the chance of House Sparrows (a
non-native species) taking over the box, do not mount on
barns, homes, or outbuildings and keep away from animal
feed areas. If Tree Swallows or Violet-green Swallows are
likely to use the box, try mounting two boxes about 3-4 m
(10 ft) apart so that the bluebirds can use one and the
swallows the other. Most nestbox hosts have found that
this practice of pairing the boxes will allow both species
to nest side by side in relative peace. Paired boxes should
be at least 100 m (300 ft) from the next pair.
A couple of mounting options: the nestbox in the background is
on an extension pole above a fence post.
These boxes have been paired to
provide habitat for both swallows
and bluebirds.
Entrance Holes
Entrance holes should be 1.5-2 m (5-6 ft) above the ground, with clear access for both birds and
monitors, facing away from prevailing winds and rain if in an exposed location (e.g., in a mountain
clearing), facing towards a safe perch (tree or shrub which is within 30 m (100 ft) of the box, but not
too close or obstructing access). Scattered 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. If
boxes are placed along roads the hole should face away from or parallel with the road so that birds
are more likely to fly along the road ditch than across the road and into the path of traffic.
Nestboxes on exposed open slopes should have the entrance hole facing away from prevailing winds.
This nestbox has been properly mounted
with clear access to the entrance hole,
so that the door opens easily, and at the
right height for monitoring and cleaning.
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Mounting
Nestboxes can be mounted on free-standing poles, trees, or fence lines (provided the fence post is
high enough; if not, an extension pole nailed to fence post will work). Use either nails or screws to
mount the box, or if you are concerned about damaging a tree, use a rope that supports the nestbox.
The door should open free and clear and be accessible for cleaning. Avoid placing boxes on fence
posts where the fence could be travelled by squirrels or
raccoons (e.g., wooden slats), or use a metal or PVC pole
to extend the nestbox above predator access. All open
pipes should be capped or sealed to prevent trapping and
killing small birds and animals. Garry Oak and Douglas-fir
trees have such thick bark that screwing a nestbox
directly into the tree (up to approximately 5 cm or 2 in)
poses no concerns for the tree's health. Please use
galvanized screws. When mounting to a tree with rope or
zip ties, it is important to loosen the tie periodically to
ensure that the tree is not being girdled. Do not mount
nestboxes to utility poles (this not only requires
permission, but also the nestboxes may be removed by
work crews at critical times, and there is a danger of
pesticide use along the utility line).
Nestboxes can be mounted on stable, free-standing poles.
Nestboxes mounted on fences with boards or slats should be on extension poles
that place them well above the “predator highway”.
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Mounting Tips
Pre-drilling all screw holes prevents the wood from splitting.
An eyebolt or piece of galvanized metal strapping at the top of the box will make suspending it
easier.
Don’t put screws or nails too deep into a tree; they may need to be removed later. If mounted
with rope, the rope might need to be loosened every few years to prevent girdling of the tree.
Make sure the nail or screw securing the door will come out easily (but hopefully not easily for
a raccoon).
If House Wrens are a problem, move bluebird nestboxes at least 60m (200') from cover (dense
brush).
The bark of mature Garry Oak trees is so thick that the tree
is not damaged if nestboxes are mounted using galvanized
nails or screws (they do not penetrate to living tissue up to
approximately 5 cm or 2 in).
Remember that the nestbox might need to be moved or
removed, though, so don’t put the nails too deep into the
tree!
An eyebolt or a piece of galvanized metal strapping at the
top of the box will make suspending it easier.
When using rope or zip ties, you might need to be creative
to get the box stably mounted at a suitable height.
Cleaning nestboxes
Please clean out nestboxes between November and
January. Bluebirds return to the Salish Sea area
early—in the past, they have been known to arrive as
early as the beginning of February. Having an empty,
clean nestbox will increase the chance they will select
the box for roosting or nesting. The screw or nail can
be easily removed so that the side panel can be opened for this purpose.
To report bluebird sightings or nesting activity, or if you have questions, please contact GOERT at
250-383-3427 or bluebird@goert.ca.
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