Putting up a
nest box is a responsibility that should not be taken
lightly. When you put up a box, a commitment is made to
provide as safe as possible place for the bluebirds to raise
their young. If this commitment is taken seriously, both you
and the bluebirds will be rewarded.
Bluebirding
is a great hands-on project but, from time to time, problems
may arise on your trail. Common problems on a bluebird trail
include the weather, house sparrows, house wrens, and
predators such as raccoons. We cannot control the weather,
and sparrows and wrens may prove to be difficult, but losses
due to raccoons can and should be controlled. Proper box
placement can be a factor in raccoon predation. Boxes placed
in pastureland are less likely to attract raccoons than
boxes placed near a wooded area with a stream, pond, or lake
nearby.
There are
two definite lines of defense against raccoons. The best way
is to keep the raccoon off the box. The second is to prevent
the raccoon from reaching into the box once it gets in a
position to try.
There are
many ways to predator-proof a box. Here are some methods
used by experienced bluebirders.
MOUNTING SYSTEMS
The easiest
way to mount a bluebird box would be to nail it to a wooden
fence post or to a tree. Although this may work well in
certain parts of North America where there are few raccoons,
it is generally not recommended. Raccoons climb trees and
walk fence lines where they may eventually find your box.
Taking the time to properly mount your boxes, may take care
of your raccoon problems.
A smooth
clean pipe is the best mounting system to use. A 10
foot piece of 3/4 inch EMT electrical conduit pipe can be
purchased for a reasonable price. It will then need to be
cut down to a length of approximately 8 feet, to place 2
feet of pipe in the ground and 6 feet of pipe above. The
electrical conduit is zinc plated and will keep its slick
surface for many years. Other heavy round pipe will also
work well. Scrap pipe found at construction sites and
salvage yards can also be used. An excellent source of pipe
is from overhead garage door companies. In their scrap piles
from discarded doors you will find either an 8 foot or 16
foot piece of 1 inch pipe.
Most
businesses will be glad to give them to you. If they are
rusty, they should be sanded smooth. Flattening the bottom
of the pipe with a heavy hammer will help stabilize the pipe
and keep it from turning. A fence post driver is recommended
over a heavy hammer for putting the pipe in the ground.
There are several easy ways to mount a bluebird box to the
pole:
Pre-drill
two 5/16 inch holes through both the conduit or pipe and the
back of the box. Use 1/4 inch bolts for anchoring the box to
the pole. The drilling can be done before placement in the
field.
OR
Wrap two
pieces of pipe strap around the pole and screw into the back
of the box on either side of the pole. Secure another small
piece of pipe strap to the back top and bend it down into
the pole to keep the box from turning.
OR
Place two electrical conduit hangers around the pole and
screw into the box.
A
method that works well for mounting lightweight boxes (i.e.,
PVC boxes) is the use of a 5 foot piece of 1/2 inch
electrical conduit slipped over a 5 foot piece of rebar
driven approximately 2 feet into the ground. A conduit
connector (with a longer bottom screw) at the base is used
to keep the conduit from turning.
A bluebird
box may also be mounted on PVC pipe. Some 2 inch PVC pipe
will slip over a metal T-post, which makes a secure system
when your box is located in a pasture with cattle. Mount
your box high enough on the PVC so that the cattle will not
have any sharp corners to rub against.
Down spouts
can also be used. A 10 foot length of down spout can be cut
into three 3 foot 4 inch pieces, which is attached to the
back of the box. This can then be slipped over a metal
T-post.
By using the
above methods, raccoon predation will be greatly minimized.
For added protection, substances can be applied to the pole.
Rub the pole down will steel wool and apply a layer of
Carnauba car wax or silicone spray. Another effective method
is to apply a coating of high quality automotive grease to
the pole. A mixture of 5 pounds of grease and one quart of
turpentine will keep the grease soft throughout the season.
Grease will eventually attract dirt and harden which may
make it easier for a raccoon to climb the pole. The grease
may have to be removed and reapplied if this happens. This
is extra work, but it is the most effective way to keep
raccoons off the pole.
POLE GUARDS
Some bluebirders prefer using a guard on the pole or post
their box is mounted on. Guards that have proved to be
successful include:
Kingston Stove Pipe
Material
List:
-
Galvanized stove or vent pipe
-
8 inch
diameter x 24 inch long
-
8 inch
circle of 1/2 inch hardware cloth
-
2 hanger
iron straps, 7 inches long
-
2 No. 8
B32 x 3/4 inch machine screws and nuts
Zeleny Cone
Material
List:
-
3 foot
diameter circle of 24- or 26-gauge galvanized sheet
metal
-
1/4 inch
round head stove bolts
-
2 hanger
iron straps.
-
Disc
blades also work well and can easily be found at farm
auctions.
Many
excellent baffles are sold at local bird stores which
include all the parts and instructions for easy mounting.
Sheet metal wrapped around a wooden post is also
recommended. The sheet metal should extend down at least 3
feet below the bottom of the box, rather than from the
ground up.
PVC Baffle
Material
List:
The baffle must be free swinging on the pipe and must wobble
when the raccoon tries to climb it. The hole drilled in the
top of the PVC cap, should be approximately 1/8 inch larger
than the pipe itself. This will keep mice from climbing up
the pole and will still allow it to wobble. An oversized
hose clamp is recommended in order to give the PVC added
"wobble".
ENTRANCE HOLE GUARDS
Noel
Guard
This
guard is estimated to be 90% effective in keeping raccoons
or cats from reaching into the box once they have gained
access to it. A rectangle of 1/2 inch hardware cloth placed
around the entrance hole will stop these predators from
reaching down into the nest box. Some bluebirders recommend
that the guard not be placed on the box until after
the bluebirds have started their clutch, while others have
had success leaving the guard on the box year round.
Wooden
Hole Guard
These are no
longer recommended by NABS. This is an extra block of wood
placed over the nest box entrance, with a corresponding hole
in its center. This extra 3/4 inch thickness makes it more
difficult for the raccoon to reach in, but unless a very
deep box is used, they are still able to reach the nest.
Similar
preventative methods apply to snakes and cats. Snakes can
climb smooth poles, even greased ones. Snakes are more of a
common problem in the southern states but some snake
problems may occur all across North America. The stove pipe
and cone guards are effective for snake control. Also
effective is a 24 inch piece of hardware cloth placed
directly under the box.
Both domestic and feral cats pose a threat to bluebirds. The
hanging guards mentioned may detour a cat but they may jump
as high as 6 feet. If cats are in your area, place your box
as high as possible on a smooth pole.
Please do not let the possibility of predation problems
discourage you from putting up a bluebird box. Mounting your
box on a smooth round pipe will greatly reduce the chance of
a loss to a predator. Any other preventative measures taken
will provide added protection.
