Photo: Duc Ly / Flickr / CC BY SA 2.0
Setting up a birdhouse in your backyard can be an exciting opportunity for birdwatching and seeing the wonder of hatchlings.
It can be tempting to give birds everything you think they might need to set up a nest. However, human intervention can harm birds or prevent them from moving in.
You do not need to put anything inside a birdhouse. If you do, birds may think it is occupied, find the materials unsuitable, or will remove them for desired nesting materials. Items like bird seeds inside a birdhouse will invite predators, other birds, and diseases to the house. Items like dryer lint and chemically treated materials pose health risks to birds.
Read on to learn more about what is ideally needed for inside a birdhouse, and what to avoid.
Inside A Birdhouse: Features
Around 85 species of birds in North America make cavity nests in birdhouses as well as in decaying wood, trees, or gaps in structures.
The type, size, and location of using a cavity to build a nest depend upon the species of bird. Some species will use a hole itself as a nest or will build one inside, such as in a birdhouse.
Birdhouses, or nest boxes, are attractive to birds if they have the following features:
- Composed of natural, untreated wood
- Walls that are insulated with wood that is ¾-inch or thicker
- Entrance hole that is species-specific yet keeps predators out
- Ample room to build a nest, if needed
- Extended, sloped roof to keep rain out
- Drainage holes and ventilation holes to keep inside cool and dry
- Grooved interior walls for grip as hatchlings exit
- Installed securely with protection from predators (more on that below)
What To Put Inside A Birdhouse (And What To Avoid): 4 Issues
Generally, you do not want to put anything inside a birdhouse. It should be a clean and empty space.
That being said, there are a few things you can offer birds so that they choose a birdhouse in your yard.
1. Nesting Materials
Birds look for suitable nesting materials to build nests for their offspring using their internal instinct.
Therefore, if you add nesting or other materials inside a birdhouse, a bird may not use it, may think it is occupied, or will remove the materials and replace them with what it wants.
The type of nesting materials may vary but include items such as:
- Spider silk
- Downy plant material
Nesting materials are woven and pressed by the bird’s body to the shape of its nest.
Considerations For Certain Species
If you are looking to attract a particular type of bird, you can offer some nesting materials inside the box.
Keep in mind though, that birds may still reject the birdhouse, even if you give them exactly what you think they need.
Also, remember that the birdhouse must be specifically designed for and mounted at the appropriate height for that species of bird.
You can contact a local cooperative extension or wildlife refuge for this information.
Some examples of birds that may accept nesting materials inside a birdhouse are the following:
- Woodpeckers (Picinae): These birds may not be bothered by a thin layer of wood chips at the bottom of a birdhouse, since they naturally excavate wood to create cavities.
- Owls (Strigiformes): Owls are opportunistic nesters, using abandoned nests. They may add materials or use a nest as-is.
Put Nesting Materials Nearby
Instead of putting nesting materials inside a birdhouse, you can create a place for birds to gather them nearby in your yard. This can offer various materials that various birds can use.
Try the following:
- Gravel and mud: Create a small divot in your yard so that a muddy puddle can form, add some small gravel to it.
- Pile of natural debris: Leave a pile of pine needles, grass clippings, bits of leaves, and twigs in a corner or your yard.
- Hanging suet cage: Use an empty suet cage and fill it with cotton fibers, natural plant vegetation, or brushed-out fur from pets.
- Make sure everything is loosely packed and in small pieces.
- Hang it from a branch on the opposite side of your yard, away from the birdhouse.
- Conversely, you can purchase a commercial hanging nesting ball or packet from the store.
- Wild yard: Let a part of your yard grow wildly without trimming it back. This creates a thicket that offers nesting materials for a variety of birds.
Avoid These Nesting Materials
Manmade materials used for nesting can cause problems for birds.
Do not offer the following:
Chemicals in clothing dyes and laundry detergent remain on the dryer lint fibers. These can be toxic to birds.
Additionally, dryer lint shrinks or falls apart when it gets wet. This poses a risk to the hatchlings and mother. Birds depend upon a study nest structure to prevent injury or exposure to the elements.
Chemically Processed Materials
Dyed fabric pieces and plastics for example can contain harmful substances for birds.
Keep your yard free from refuge (including cigarette butts), and do not intentionally offer these kinds of items to birds.
While birds will use manmade materials if it fits their nest design, it is best for them to use natural materials.
Herbicides And Pesticides
The use of these chemicals in your yard exposes birds and other wildlife to toxic chemicals.
When birds consume insects and use nesting materials with these chemicals on them, they can become ill and die.
Pesticides also reduce the food supply for birds, and they may not nest in an area with a poor food supply.
Human hair is long, strong, and thin. It can ensnare a bird’s leg, affecting its circulation or even severing it.
Yarn Or String
Like hair yarn or string can entangle a bird, cutting off circulation or trapping it.
It is not recommended to use sawdust with hatchlings, since this can pose a breathing hazard with the fine, dusty particles.
Instead opt for wood chips certain for birds, such as woodpeckers.
2. Food And Water Sources
Cavity nesting birds like to build nests in an area that has readily available food and water sources.
However, they also prefer to nest away from noisy bird feeders and bird baths to create a calm and quiet atmosphere for their hatchlings.
What To Do
Bird feeders and bird baths should be placed on the other side of your yard.
This keeps the noise level down, and keeps other birds and creatures such as squirrels, away from the birdhouse.
Never put bird seeds directly inside a birdhouse whether it is empty or occupied.
This invites danger from predators and disruption from other birds.
Uneaten or trapped seeds inside can become spoiled and rotten as well posing a health risk to a bird and its hatchlings.
3. Protection From Predators
Birds like quiet, uninterrupted places to nest that are 15 to 25 feet away from competing birdhouses. They choose birdhouses that are high enough, and that face in an ideal direction.
This is to protect them from predators, prevailing winds, and inclement weather.
Eggs, hatchlings, and birds are food sources for predators such as cats, snakes, raccoons, lizards, bears, other birds, and more.
Protecting a birdhouse from predator invasion makes it a safer place to nest.
Modifying or installing features on a birdhouse can keep birds and their hatchlings safe.
A metal plate is attached over the entrance hole to prevent predators from clawing or pecking at the hole to make it bigger.
An elongated plastic or metal tube 2 to 3 inches long can be attached over the hole for the bird to enter.
This can keep predators out since they cannot stretch their forearms far enough into the hole.
Keep in mind that this tunnel entrance could serve as a perch for predators. However, it is likely to be slippery.
Remove any perches on the birdhouse. Perches can offer a way for a predator to grip onto the birdhouse and reach inside the hole.
Mother birds do not need them for entrance into the birdhouse.
Predators, such as squirrels and raccoons could perch on the roof of a birdhouse and reach down into the hole.
Extend the roof or purchase a birdhouse with a roof that extends 5 inches or more out from the birdhouse. The sides of the roof should extend 2 or more inches out as well.
This makes it difficult for predators to reach and maintain balance if trying to access the hole.
Baffles are tube or dome shapes that can be attached above and below birdhouses (and feeders). These help to keep competing or predatory animals away.
It is very difficult for a climbing creature to maintain a grip or move around these barriers.
This video demonstrates how to install a squirrel baffle:
4. Create A Clean Inside: Clean The Birdhouse Out After Use
A birdhouse should be cleaned out after a brood has left. You will notice at some point that there is no activity at the house.
Old nesting material may be contaminated with feces, mold, insects, parasites, or disease making it an undesirable place for nesters.
To clean out a birdhouse, do the following:
- Remove the empty nest.
- Clean the birdhouse out with mild, soapy warm water.
- Use unscented dish detergent.
- Rinse it clean with boiling water.
- Allow it to air dry fully.
However, if you see new eggs or hatchlings in the nest, it is illegal to disrupt them. Leave them be, and the mother will tend to them.
You should not put anything inside a birdhouse. A birdhouse should be free of feces, bird seeds, and nesting materials.
Items like dryer lint, cigarette butts, string, long human hair, and pesticides can pose health risks to birds and their hatchlings.
Placing bird seeds inside a birdhouse can invite predators in. The seeds can also become old or decay offering an unhealthy food source.
Cavity nesters will instinctively find suitable nesting materials for their nests and will opt for natural materials found nearby in your yard.
It is best to mount a birdhouse in a protective area in such a way that it is free from disruptive birds or predators, as well as harsh weather conditions.
Once a clean birdhouse is mounted in an ideal way, the mother bird will take care of the rest for raising healthy offspring.