Features of a Good Birdhouse
Nest boxes come in many shapes and sizes. This can make choosing a nest box design confusing. Whether you plan to build or buy a nest box, it should have the features listed below. Also, make sure that it is durable, and easy to monitor and clean.
- Untreated wood (Pine, Cedar, or Fir)
- Drainage holes
- Thick walls (at least 3/4″)
- Ventilation holes
- Extended, sloped roof
- Easy access for monitoring and cleaning
- Rough or grooved interior walls
- Sturdy construction
- Predator guard
- No outside perches
- Mounted on a metal pole
It’s well constructed
Untreated Wood
Use untreated, unpainted wood, preferably cedar, pine, cypress, or for larger boxes (owls) non-pressure-treated CDX exterior grade plywood.
Galvanized Screws
Use galvanized screws for the best seal. Nails can loosen over time, allowing rain into the nest box. Screws are also easier to remove for repairs or maintenance. Do not use staples.
It keeps birds dry
Sloped Roof
A sloped roof that overhangs the front by 2-4″ and the sides by 2″ will help keep out driving rain, while also thwarting predators. Add 1/4″ deep cuts under the roof on all three edges to serve as gutters that channel rain away from the box.
Recessed Floor
A recessed floor keeps the nest from getting wet and helps the box last longer. Recess the floor at least 1/4″ up from the bottom.
Drainage Holes
Add at least four drainage holes (3/8″ to 1/2″ diameter) to the floor to allow any water that enters the box to drain away. Alternatively, you can cut away the corners of the floorboard to create drainage holes.
It helps regulate temperature
Thick Walls
Walls should be at least 3/4″ thick to insulate the nest properly. (Boards sold as 1″ are actually 3/4″ thick.)
Ventilation Holes
For adequate ventilation, there should be two 5/8″ diameter holes on each of the side walls, near the top (four total).
It keeps out predators
No Perches
A perch is unnecessary for the birds and can actually help predators gain access to the box.
Predator Guards
Although predators are a natural part of the environment, birdhouses are typically not as well concealed as natural nests and some predators can make a habit of raiding your boxes. Adding a baffle helps keep nestlings and adults safe from climbing predators. Three time-tested options are cone baffles, stovepipe baffles, and Noel guards.
Cone Baffle –
A metal collar about 3′ in diameter surrounding the pole underneath the nest box.
Stovepipe Baffle
The most complex, and perhaps the most effective. These baffles are generally 8″ in diamter and 24-36″ long.
Noel Guard
A wire mesh tube attached to the front of the nest box. Use this guard in combination with another, or attach it to boxes installed on trees.
Common Nest Predators
Snakes
Many snakes are excellent climbers and can easily surmount and unguarded pole. Snakes most likely to climb into birdhouses are generally non-venomous (such as racers and rat snakes) and helpful at controlling rodents. Avoid installing nest boxes nest to brush piles.
Raccoons
Raccoons are intelligent and can remember nest box locations from year to year. They can be abundant in populated areas. Mount nest boxes on a metal pole equipped with a baffle; avoid mounting them on trees or fence posts.
Chipmunks
Chipmunks are both a nest predator and a competitor for nest boxes. To keep chipmunks out, mount boxes away from trees on a metal pole equipped with a baffle.
Cats
Cats are excellent jumpers and can leap to the top of a nest box from a nearby tree or from the ground. Mount your box high enough and far enough away from trees so cats cannot spring to the top of the box in a single leap. Keep pet cats indoors for their own safety and for the safety of birds.
It has the right entrance size for the right bird
By providing a properly sized entrance hole, you can attract desirable species to your birdhouses while excluding predators and unwanted occupants. Below are the requirements for some common North American species that nest in boxes.
Don’t want to give a home to European Starlings? 1 9/16″ is the smallest hole size that they can fit into, so select a smaller hole size.
Don’t want to give a home to House Sparrows? 1 1/4″ is the smallest hole size they can fit into, so select a smaller hole size.
It helps fledglings leave the nest more easily
Rough Interior Walls
The interior wall below the entrance hole should be rough to help nestlings climb out of the box. You can roughen smooth boards with coarse sandpaper.
Interior Grooves
A series of shallow horizontal cuts, like a small ladder, works well in medium-sized boxes meant for swallows and bluebirds. Swallows, in particular, need a little help climbing out of boxes.
Duck Boxes
For duck boxes, staple a strip of 1/4″ mesh hardware cloth on the inside of the box from floor to entrance hole to help the ducklings escape deep boxes.
It makes placement and maintenance easy
Extended Back
A few extra inches at the top and bottom of your birdhouse can make it easier to mount on a metal pole. Alternatively, you can pre-drill mounting holes in the back panel before assembly and use a short-handled screwdriver to install the box.
Hinged Door and Sturdy Latch
A hinged side gives you access for cleaning and monitoring your nest box. A latch or nail keeps the box securely closed until you are ready to open it.