Ever since I was a child, a favorite pastime during the summer evenings was watching bats fly over an open yard.
I’d lie down in the shaggy grass and watch them hunt, admiring their acrobatics. If I listened carefully and the night was still, I could hear a few fluttery flaps of their wings, and maybe a squeak here and there.
Now, as an adult, I still watch for bats during the summer. When I see them, I feel that same sense of wonder I experienced as a young’n.
I was lucky enough to have a few roosting behind the shutters of an old apartment building, right outside my window. And when I lived in Arizona I would visit an old bridge in town that was home to a colony of thousands. They’d all take flight at about the same time, following the first one daring enough to enter the twilight sky.
Bats have always been a welcome part of my life and encouraged residents in my garden. They offer tremendous benefit to the garden and the neighborhood, and they are a sign of a healthy ecosystem. However, like many critters in these modern days, they are beset by a number of challenges to their continued existence.
Keep on reading to get a short and sweet overview of the benefits bats provide, the threats they face, and lastly, a guide on how to encourage them to live in your garden and near your home. And, you guessed it – you’ll learn how to build a bat box!
Now let’s get to it.
Flying Friends Eagerly Eat Bugs
Yup, that’s right. And not just any bugs. Bats favor mosquitoes and other flying insects.
The next time you’re shopping for citronella candles, geraniums, and other mosquito deterrents, consider giving a few flying friends a home instead. In exchange for aiding your local ecosystem by providing an inviting home, you receive 100% all-natural flying insect control in return.
The typical bat weighs about half an ounce, or 15 grams. They must eat at least ¼ of their body weight every night to survive, with pregnant females eating up to their entire body weight. When you consider the miniscule and almost insignificant weight of your average mosquito you can imagine how many nasty ol’ bugs a single bat can devour in one evening.
Now consider that they also live together in colonies, and you’ve got yourself some powerful automatic insect control.
There are a host of other benefits to having these creatures in your garden, but this one takes the cake, as far as I’m concerned.
Get Your Facts Straight
There are 44 species living in North America, some of which are endangered and others that are listed as species of concern. They are facing this increasing level of decline because of environmental and manmade stresses.
In 2007, in caves in New York, bats were first discovered to be infected with white-nose syndrome. It is a disease caused by a fungus called Pseudogymnoascus destructans that is often found around their noses.
The disease causes the animals to use up their stored energy during winter hibernation. Because they live in colonies, it tends to spread quickly, resulting in some population losses greater than 90%.
It is difficult for bat populations to bounce back because they have a single offspring each year, and live to typically 5 to 10 years of age.
Despite the common comparison, bats are nothing like rodents. Mice, rats, and other rodents tend to have short lives and breed in massive quantities, whereas each offspring produced is a major investment for the bat.
Manmade stresses impact total population counts as well. The common belief is that bats are rabies-infested devils always seeking a nice head of hair to get tangled in.
I blame ‘80s movies for this stereotype.
Unfortunately, bats have been targeted for extermination by humans on many levels. Their natural habitats are increasingly targeted by humans for safety reasons: closing old mines that are used as colony homes, or clearing dead trees that they can roost inside of.
Facing environmental dangers and pressure from humans, they can find themselves in an increasingly risky situation. Luckily, we can help, and in the process rid our yard of legions of mosquitoes.
Making Your Garden Attractive
Compost heaps and water features can attract the insects they like to feed on, which makes them beneficial to bats. If you aren’t already composting, here’s one more reason to do it!
Consider leaving some of the less destructive caterpillars in the garden as well. They will eventually turn into moths, at least some of which are fated to then be devoured by a hungry bat.
If You Build It, They Might Come
The ideal solution to invite bats into your garden is to allow natural homes for them to find. After all, the goal of constructing a DIY shelter is to closely mimic the natural environment that they prefer… so why not just provide that type of environment?
Bats will naturally find homes in the loose bark of trees, cavities in a trunk, or splits in branches. If it’s safe to maintain a tree in this condition in your yard, it’s already a perfect place for them to roost.
Although bats have been flying around for tens of millions of years, the practice of building houses for them is a nascent practice. Unfortunately, they don’t seek apartments and housing with a handy internet search, so there’s no telling if they will take up residence in the house you create.
Depending on who you ask, the wooden structure will remain untouched for any number of reasons: the structure isn’t big enough, or the location isn’t perfect, or the local wildlife has already taken up roost in different dwellings. It’s a possibility that the structure will never be inhabited.
But just like the lottery, you can’t win if you don’t play. The worst case scenario when building one of these structures is that you’ll have a fun afternoon and then have an interesting conversation piece for visitors. But you just might luck out and give a home to some bats in need.
A Box to Call Home
If conditions permit, adding a bat box into the garden is a great way to invite our flying friends into a safe home. It is a project that requires some basic carpentry but is such a rewarding experience.
These shelters need to be placed in a sunny location, but not too sunny. East-facing is usually best, where they get morning light but are protected from afternoon sun.
They need to have a source of water and to be out of reach of predators. The boxes should be examined for damage and insect infestations once a year when bats are not taking up residence. If there are no insects making themselves at home, then the structure does not need to be cleaned.
The amount of guano (droppings) that falls is minimal and is usually washed away by natural processes like rain and wind. If you notice that a pile is collecting it can be tossed into garden beds; put on disposable latex gloves and make sure not to contact the guano with your skin. Using a shovel, scoop up the pile and simply top dress into your garden beds.
Alternatively you could make guano tea. Drop about one cup of guano in one gallon of water and allow to steep overnight, then water any non-edible plants with it for a deep-root feeding.
The following is a simple design, but it can serve to provide a home for those in need of one. Construction is simple, but take your time and remember – measure twice and cut once!
DIY Bat House
- One (1) 2’ x 4’ section of ½” outdoor-grade plywood (nontoxic)
- One (1) piece of 1” x 2” x 8’ cedar
- One (1) 1” x 4” x 28” cedar or pine board
- Twenty-five (25) 1½” coated deck screws (you’ll have extras)
- One (1) pint dark (brown or black) nontoxic water-based waterproof exterior stain
- One (1) pint water-based exterior primer
- One (1) quart dark (brown or black) water-based exterior paint or stain
- One (1) tube of nontoxic, paintable, exterior latex caulk
- Drill bit (appropriate size for the deck screws
- Table or hand saw
- Circular saw (optional)
- Paint brushes (cheap and disposable work fine if you aren’t reusing the brushes)
- Caulk gun
- Utility knife (any sharp blade will do)
- Tape measure/yard stick
1. Measure and then cut the plywood into three pieces:
- 26 ½” x 24” to be used as the back plate
- 16 ½” x 24” to be used as the top half of the front plate
- 5” x 24” to be used as the bottom half of the front plate
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2. Use a utility knife, hand saw, or circular saw (set to 1/16” depth) to carefully cut grooves into the back plate. These should be spaced about ¼” to ½” apart, and are used as grips for roosting.
The bottom portion of the box should also have the grooves cut into it to serve as a landing area.
3. Apply two coats of a dark, water-based stain to interior surfaces of the back plate and both pieces of the front plate (i.e. the side with the grooves you cut). Allow to fully dry.
Don’t use paint, because it can fill up the grooves you just added.
Bats want a dark home, so that’s why we stain the interior.
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4. Cut the 1”x2”x 8’ cedar strip into one (1) 24” piece and two (2) 20 ½” pieces.
These strips will be used as the spacers and are sandwiched between the back plate and the front plates. These are called furrowing strips.
5. Apply caulking to all 3 of the furrowing strips and attach to the inside of the back plate (the side you cut grooves into).
The 24” furrowing strip will be placed flush with the top of the backboard. The two 20 ½” furrowing strips will each be placed flush on the sides of the board, butting against the 24” piece of cedar.
Once they’re all attached, it will resemble a frame.
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6. Caulk the edges of both sides of the front plate. Attach the top half of the front plate first so that it sits squarely on the furrowing strips.
Leave a ½” space between the top half and the bottom half of the front plate. This functions as a vent.
7. Attach the 1” x 4” x 28” piece of cedar or pine to the top of the box to function as a roof.
8. Caulk every joint of the exterior of the box where wood touches wood. Bats want to have a dry home, free from drafts.
9. Use a drill bit to pilot five (5) holes evenly spaced on the left and right side of the box. These should punch through the front piece and the furrowing strip, and then into the back plate.
Also drill three (3) holes along the top, again reaching through the front plate, furrowing strip, and into the back plate.
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10. Use a drill to add the screws into the piloted holes, securing the box to form a solid and stable structure.
11. Apply a coat of the water-based primer to the outside portions of the box. When dry, apply three coats of paint or stain to the exterior. It’s a safe bet to allow the structure to fully dry overnight before the final step.
12. Time to mount it! This can be done on the edge of a house (usually the east-facing side) or on a tall pole (10’-15’ tall).
Although possible, it’s recommended that you do not mount to a tree because it invites problems – easy access for predators, and a lack of sunlight and ventilation.
Consider adding a French cleat to the reverse side of the box when attaching to a solid wall, or mount to a tall post using brackets or an additional wooden support.
Building a house for them to call home is a great way to invite bats into your backyard and garden. This guide offers construction points on a basic structure, a welcome addition to almost any yard or garden. These cute-as-beans fliers will appreciate the home and pay you back by offering free pest control!
Don’t be discouraged if it takes time for the bats to find their new residence. It can take a few years before they discover it.
Bats are loyal to their roosts, but that means that once you have a few tenants, they are likely to return year after year. Besides, gardening is synonymous with patience!
When I began to read about the construction of shelters for these guys, it brought back a flood of memories. Hopefully you can add a few memories yourself when watching your own local insect-loving residents fly their roost.
Don’t forget to share your own experiences and questions with us in the comments! And if you’re looking for more information on attracting local wildlife to the backyard, check out our review of Nancy Lawson’s book The Humane Gardener.
Product photos via Bat Conservation International, Dewalt, Hillman, Newborn Brothers, and Skil. Uncredited photos: Shutterstock.
About Matt Suwak
Matt Suwak was reared by the bear and the bobcat and the coyote of rural Pennsylvania. This upbringing keeps him permanently affixed to the outdoors where most of his personal time is invested in gardening, bird watching, and hiking. He presently resides in Philadelphia and works under the sun as a landscaper and gardener, and by moonlight as a writer. An incessant questioning of “Why?” affords him countless opportunities to ponder the (in)significance of the great and the small. He considers folksy adages priceless treasures and is fueled almost entirely by beer and hot sauce.