Forget letting birds nest in cute but unsafe birdhouses! If you really want to help wild birds, provide proper nesting boxes made for specific species and do what you can to prevent birds from using other hazardous nesting locations.
If you want to make your own, there are several free plans for building nesting boxes here.
The Best Things We Can Do For Birds
- Provide proper nesting boxes for wild birds to raise their young. A proper nesting box is designed for a specific species to suit their unique needs. Local at-risk or endangered species in your area may benefit from nesting boxes.
- Decorative birdhouses, hanging teapots, and other garden art are not safe for nesting birds —even if they choose to use them. These unsafe nesting spots leave birds vulnerable to additional threats including predators, harsh weather conditions, and may trap chicks inside. Block off any entry ways to prevent use by birds and provide nesting boxes instead.
While “birdhouse” and “nesting box” have similar definitions, here we use “decorative birdhouse”‘ to mean garden decor that is not safe for birds.
Common Nesting Problems
If you have birds living around your home or garden you’ve probably noticed they can choose some rather creative but potentially dangerous nesting spots.
It could be a nest up on the porch lamp by your front door, in a hanging basket on the patio, or in a colorful, garden art teapot hanging on the garden fence.
Some may even return year after year to the same location.
We hope these creative nesters fair well and manage to raise a healthy brood but these ad-libbed nesting spots can be really problematic. While mildly inconvenient for us, they can be deadly for the birds.
Life as a wild bird is hard enough. Along with the usual stress that comes from protecting eggs in a nest and then raising chicks, these awkward nesting spots bring additional disruptions like noise, light, people coming and going, and predators scouting their vulnerable location.
Birdhouses and garden art used as nesting spots are also worrisome.
So what can we do?
If the nest is established, let it be. Prevent disruptions as best you can. In a few weeks—we hope—those chicks will fledge.
Long-term, the ideal is to restore as much natural habitat as possible. Birds need nature—not us. This means the whole circle of life including trees and shrubs, flowering plants, fresh water, and a pesticide-free environment that ensures a plentiful supply of delicious, juicy bugs to fuel the parent birds and fatten up those chicks.
We can also provide nesting boxes—not decorative birdhouses—which, if designed to suit the species and properly located, will give birds their best chance at raising their young without added stresses.
Each Species Has Unique Needs
When built right, nesting boxes are uniquely-designed for the needs of each individual species based on years of research about their size, abilities, and behaviors.
Whether you follow plans to build a nesting box or buy one readymade, it should be built with the right specifications (height, width, depth) including an entry hole sized for the specific species you are housing. I’ve listed recommended entry hole sizes here.
Other bird species may also try to occupy the box but, if the dimensions are right, this greatly reduces the chance of invasions or take-overs from other larger and more aggressive species.
It’s pretty cool when you build a box for a specific bird and they settle right in and successfully raise their young.
I’ve listed free plans in the Resources section.
Block Off Your Decorative Birdhouses
Even if birds seem interested in nesting in your decorative birdhouses (or other garden art), do your best to prevent it.
We may never notice it but every year countless birds die in “cute” birdhouses.
I first learned about this years ago when attending a talk at a Conservation Authority. The team shared how they placed wildlife cameras on various birdhouses and monitored the activity for several seasons. It soon become clear that, while many birds would use the decorative boxes, their broods rarely survived.
Decorative birdhouses (or badly-designed nesting boxes) can be unsafe for various reasons:
- The size and shape makes it accessible to a range of predators like snakes, racoons, chipmunks, as well as other competing bird species.
- The nesting area lacks protection from temperature extremes, wind, rain, or snow.
- Perches (which are never recommended) enable predators to stand and attack.
- Located close to people or pets, the bird now has more worries beyond regular nesting duties.
The best option is to block any openings entirely. I have a big, old martin house I use as garden art and each entry way is covered in hardware cloth.
That, along with providing proper nesting boxes, has benefited many generations of birds.
Teapot birdhouses like you see in the next photo are fun but not recommended. The teapot shape with its large opening as well as the wooden shelf both easily allow predators to raid the nest. The large teacup may fill with water and you never want a nesting site to attract other birds to perch, eat, or drink.
Birds That Use Nesting Boxes
Throughout North America there are approximately 85 species of birds that nest in tree cavities.
Some, like woodpeckers, create their own nest holes, while others are “secondary cavity-nesters” and use whatever existing cavities they can find.
About half of all cavity-nesters are willing to use human-made nesting boxes if the setup and location is suitable.
You can see why there is a housing shortage for these birds in urban areas. We often remove dead or decaying trees for safety reasons but that’s exactly what these birds need for their nesting spots.
These are some birds that may use nesting boxes in Canada and the United States.
- Bluebirds | Eastern, Mountain, Western
- Chickadee | Black-capped, Carolina
- Flicker | Gilded, Northern, Red-shafted, Yellow-shafted
- Flycatcher | Ash-throated, Great Crested
- Kestrel | American
- Owl | Barn, Barred, Eastern Screech, Western Screech
- Swallows | Tree, Violet-green, Purple Martin
- Titmice | Black-crested, Juniper, Oak, Tufted
- Wood Duck
- Woodpecker | Downy, Hairy
- Wrens | Bewick’s, Carolina, House
Other birds like American Robins, meadowlarks, thrashers, phoebes, house finches, and Carolina wrens may instead use shelves or platforms placed under house eaves.
This has instructions for a nesting shelf I built for a robin to stop her from choosing other awkward and dangerous options around our house. (It worked.)
If you have a lot of smaller birds living in your garden, it’s not the place to offer a nesting box for birds of prey like owls that may just dine on your little friends.
Tips For Choosing The Right Nesting Box
What Makes A Good Nesting Box
Here are things to look for in nesting boxes:
Wood | Natural, untreaded, cedar, pine, cypress are all good options. Should blend in with surrounding environment. Wood thick enough to insulate from extreme heat or cold.
Paint or Stain (natural colors) on exterior only and only if necessary; no paint or stain in interior.
Rough Interior Walls | When the time comes for the young birds to leave the nesting box, they need to be able to climb up to the hole and fly away. Abilities differ with each species but in general we need to be sure the interior wood has a rough surface they can cling to. Birds like bluebirds specifically need cross-hatched grooves in the wood to be able to climb out.
Size and Shape | Dimensions depend on what’s best for each bird species. If buying a readymade box, check if the brand is using specifications from a trusted bird society or authority—not just that they borrow a trusted name like Audubon, but actually follow the recommended best practices.
Generally, most nesting boxes are about the size of a shoebox although owl and duck boxes are larger.
Predator Guard | Add a block or guard at entry hole to deter common predators such as snakes, racoons, chipmunks, opossums, or cats. This shows a predator block on my wren box which has thwarted numerous predators.
Accessibility | One wall should be hinged with a latch to allow for cleaning and checking on the nest.
Ventilation & Drainage | Upper walls should have air ventilation holes approximately 5/8-inch in size.
Floor board should have drainage holes approximately 3/8-inch in size. It also helps to position the floor board higher than the box sides to further prevent any water buildup.
Perch-Free | We used to think perches “helped” birds. In reality, they give predators a place to stand while they attack. When a nesting box is properly designed and positioned with a clear flight path, the bird can easily fly directly inside without any need to perch. If a nesting box has a perch but is otherwise properly designed, just remove the perch and use it.
No Nesting Materials | Do not put any nesting materials inside the box: the birds do this themselves. And, by adding materials you may be signalling to birds that the box is already occupied.
Right Size Entry Hole | Entry hole should be the precise size and placement needed for the species (see chart below).
Nesting Box Hole Size Chart
If you are buying a readymade nesting box, check that the hole size (along with all the other dimensions) match the recommendations issued by birding societies.
So many readymade nesting boxes are constructed without any regard for the birds and are not safe to use.
Best Entry Hole Sizes
- 1-inch (2.5 cm) | Brown-headed Nuthatch
- 1 1/8-inch (3 cm) | House Wren, Bewick’s Wren, Chickadees
- 1 1/4-inch (3.25 cm) | Prothonotary Warbler, Red-breasted Nuthatch, Titmice
- 1 3/8-inch (3.4 cm) | White-breasted Nuthatch, Violet-green Swallow, Tree Swallow
- 1 1/2-inch (3.8 cm) | Eastern and Western Bluebirds, Bewick’s & Carolina Wren
- 1 9/16-inch (3.9 cm) | Flycatchers*, Mountain Bluebird
*Some resources say 1 3/4-inch (4.4 cm)
- 2 1/2-inch (6.35 cm) | Northern flicker
- 3-inch (7.6 cm) x 4-inch (10 cm) | Screech Owls, American Kestrel
- 4-inch (10 cm) | Pileated Woodpecker
Best Nesting Box Locations
As mentioned, birds need more than a nesting box to raise their young: the entire environment matters. The best location for a nesting box will depend on the species.
The bird (or birds if it’s a mating pair) need to feel relatively safe and secure with lots of food sources available and few, if any predators present including domesticated cats or dogs.
Birds are, by necessity, territorial. Spreading out the boxes helps ensure there is not too much competition for resources. Look up the recommended spacing for your species—often one or two boxes total are the maximum recommended in a typical suburban backyard. Any more and there may be battles or they go unused.
- Eastern bluebirds tend to prefer a site as far from our houses as possible near the edge of forest. The box height is (usually) recommended between 5-8 feet off the ground with an unobstructed flight path going straight to the box.
- Chickadees or wrens are attracted to nesting boxes near shrubs or other sheltering spots, perhaps 3 to 5 feet off the ground.
- Purple martins are birds that will nest communally in large multi-family nesting boxes situated up on posts some 15-20 feet above the ground.
Frequently Asked Questions
When should I put nesting boxes out?
It’s great to have boxes ready to go in late winter before mating season starts, but any time is fine. Many birds are nesting from spring to fall, raising several broods, and may also use boxes to roost in cold weather.
Do birds use nesting boxes in winter?
Yes, birds may roost (sleep or rest) in nesting boxes during the winter for protection from harsh weather.
How do you clean nesting boxes?
Nesting boxes should be cleaned each time a brood has finished nesting. You will know it’s time when the fledglings have left the box, off to live in the wild.
Cleaning and disinfecting is particularly important to help prevent the spread of pathogenic diseases and parasites in wild bird populations.
To clean a box, wear protective gear including eye protection, gloves, and a mask and work outdoors.
Remove all nesting materials from the box and wash, disinfect with a bleach solution, rinse, and dry thoroughly before rehanging. These instructions for cleaning bird feeders apply to nesting boxes as well.
How can I keep invasive or aggressive species out of my nesting box?
While it’s impossible to keep all predators or aggressive species out of nesting boxes, there are a few things you can do to reduce the likelihood.
First, choose the right box for the bird species you want to host. It must have entry holes that suit the species and not any larger.
In some areas European Starlings will invade nesting boxes. They can fit through openings that measure 1 9/16-inch (3.9 cm) or larger.
What kind of nesting materials should I put in a nesting box?
You should not add any materials to a nesting box. Birds will source and provide exactly what they need to build a nest in the box that is just right for their young.
Free Nesting Box Building Plans
- Chickadee Nesting Box Building Plans
- Wren Nesting Box Building Plans
- Bluebird Nesting Box Building Plans
- Robin Nesting Shelf Building Plans
- Nestwatch | All About Birdhouses
Audubon Birdhouse Book, Revised and Updated
Building, Placing, and Maintaining Great Homes for Great Birds
by Margaret A. Barker, Elissa Ruth Wolfson, National Audubon Society
The Audubon Birdhouse Book is the most authoritative book available for creating safe, sturdy, and easy-to-build homes for many of North America’s favorite birds. This updated second edition includes important new and timely topics including impacts of climate change on birds, nestbox monitoring for community science, native plants, and how birders can help birds.
~Melissa the Empress of Dirt ♛