Infrared Camera Bat House

So why spend time building a bat house?  Bats are just blind gross rodents that get tangled up in human hair, feed on blood, nibble on your home siding, and transmit rabies right?  So why would you want to attract them on to your property?  Well let’s get a couple things straight first; bats are not rodents, they in fact have a skeletal structure very much like our own, their wings are pretty much webbed hands.  Bats are not blind, they can’t see color but they can see better at night than humans can; bats’ ability to echolocate also gives them a navigational edge over most nocturnal animals.  Bats can detect objects as thin as human hair, so avoiding your hair is quite easy for them.  There are bats that consume blood, they don’t suck the blood out though, they lick the blood from small cuts they create.  These types of bats rarely target humans and the blood commonly comes from cattle and birds.  Blood feeding bats live south of Texas so it’s pretty much impossible to attract blood feeding bats in the U.S. anyway.  Bats don’t nibble on home siding and don’t destroy the exterior caulk on windows, why would they wear down their teeth chewing on something that doesn’t feed them?  In the past 40 years fewer than 40 U.S. citizens have received rabies from bats, you have a better chance of dying from a bee sting.

Well now that I have cleared up a few misconceptions the question still remains, why do I want to attract bats to my property?  If you are involved in agriculture or gardening bats will be more than happy to help you out.  Perhaps the single most important ecological service bats can provide us is a safe and effective alternative to the habitual use of pesticides.  Studies have indicated that just one colony of big brown bats consisting of 150 individuals can consume enough corn rootworm beetles to prevent roughly 33 million eggs from being laid within a season.  These magnificent creatures could one day provide ecological services near the scale of European Honey Bees.  A study of bridge habitat in Texas revealed that roughly 4,250,000 bats spanning 24 species were living within only 211 structures; the total number of structures amounted to 2,421.  The authors suggested retrofitting existing structures to accommodate more bats. After discussing the idea with construction companies and engineers, the authors of the study estimated that the cost of retrofitting existing structures for tax payers would be either very small or nonexistent.  Creating more bat habitat would also save a large amount of money by reducing the amount of money invested in pesticide application.  Bats not only aid the agricultural world, they can have a large positive influence in residential areas as well.  An individual bat can consume over 1,000 mosquitoes within an hour, thus reducing the sheer annoyance associated with mosquitoes as well as the probability of contracting vector borne illnesses such as West Nile Virus.  Some residential pests will also avoid aggregations of bats, so simply having the bats nearby can be a great benefit.

  If you are interested in attracting bats follow the instructions below.  Attracting bats is pretty simple, just build them a cozy home to live in.  Bats don't mind tight places so all bat houses are pretty much the same, just take two pieces of wood sandwich them together with a gap in between them and viola, you have just made a bat house.  My building plans are based off a design by Bat Conservation International, my design also includes a way of viewing the bats inside the bat house.  Bats, just like humans, can't see infrared light so if you can put an infrared light and infrared sensitive camera inside the bat house you can see what is going on inside the bat house.  In the instructions below I provide step by step instructions on how to build and install your own infrared light and camera rig using a lot of materials you may already have around the house.  Once construction of the bat house is complete putting it up on the the south or east sides of your house is best.  The south and east sides of a house will expose the bat house to the most sunlight during the day which will warm up the bats.  The bat house should also be placed 10' or higher from ground to prevent predators from getting to the bats, more information about placement of bat houses can be found on the Bat Conservation International website.  Don't get discouraged if bats don't take to your house right away, bats will probably start using the house in early summer.  You may need to have your bat house up for a whole year though before bats take notice of it, so be patient.  When your bat house is discovered by bats though, the bat house can provide years of enjoyment and exploration.

What you need: 

one piece of 2' x 4' x 1/2'' outdoor grade plywood
one 1" x 2" x 8' wood board
one 1" x 4" x 3' wood board
*I found some of the wood for this project in my hardware stores' scrap wood section

Paints (all exterior grade and water based):
one pint dark stain
one pint primer
one quart dark paint (colder climates require darker colors, Bat Conservation International has a temperature map
indicating the best color to use depending on the where you live)

one tube latex caulk (darkest color you can find)

about 30 1" deck screws

Electronics (all of these electronic parts can be purchased at radio shack, just tell them what you want and they should help you out):
web camera (old ones lying around the house will work, you don't need to
go out and buy a new one for this project)
infrared LED (you could acquire these from things like old remote controls as well, it's what remotes use for data communication)
220 ohm resistor
wire (just a couple of inches)
solder (enough for a couple solder joints)

latex glove
silica gel

circular saw
cutting surface
wood spade
solder iron
hot glue gun
problem solving skills!


Cut plywood into three pieces.

Cut the 1" x 2" x 8' board as shown.  Also cut the 1" x 4" x 3' board  down to 28", this will be the roof of the bat house.

This is pretty much what the finished product will look like minus the roof.  Note the 1/2" gap between the two boards, this will provide the ventilation for the bat house.

This is the gap bats will use to enter the bat house.

The bats need something to grab onto inside the bat house.  Cut out 1/32" deep channels for them to grab onto.  Channels should be roughly spaced 1/4" away from each other (this doesn't need to be exact).

I adjusted the guard of my circular saw to allow me to cut very shallow channels into the plywood, then I cut along the red lines I had made.  If you do not have a circular saw, a hand saw will work just as well.  Remember to take the appropriate safety measures when operating a manual or circular saw.  The channels don't need to be exactly straight, in the picture you can see several of mine intersect with each other.

Get out your dark stain and stain all of the interior wood of the bat house.  Using a stain prevents the channels you just made from being filled up with paint.  You will need to apply two coats.

While you are waiting for the stain to dry prepare you electronics.  Disassemble your web camera and unscrew the lens housing from the body of the camera.  you will notice a reddish piece of clear glass sitting behind the lens of the camera.  This is the infrared filter and it needs to be removed in order to make your camera more sensitive to infrared light.  I had already removed the red glass from my camera, but it is located roughly where the red square is within the picture.  You can use pliers or a screw driver to chip the glass away, the glass is sharp so make sure you use eye protection while chipping the glass away.  Take special caution to not damage the lens underneath the filtering glass. 

The back circuit board of the camera will have a wire that goes from the camera to the USB connection of a computer.  With your camera plugged into acomputer test the leads of the plug with the multimeter and look for the +5volt and ground terminals.

Solder wires onto the the +5volt and ground terminals.  Put your 220 Ohm resistor in series with your infrared LED.  The LED will have a flat spot around its rim.  This flat area represents the side of the LED that needs to be soldered to the ground terminal.  It does not matter which side of the LED you solder the resistor onto.

This is just the wiring from another angle.

I removed some more plastic from the lens housing so I could fish out the the wires and make them come out the front of the camera.  This will make it easier to put into the bat house.

You will not be able to see the infrared light while the LED is on.  To test the circuit though you can turn out the lights and see if the camera detects its surroundings.  You can also take a photo of the LED, cameras will show a faint purple glow.

Because this camera will be outside you want to prevent moisture build up, which can fog the lens or damage the electronics inside.  I put silica gel inside the camera case.  The cat litter I use is made of the stuff, but you can also use the silica packets that are used in the food and garment industry to preserve goods.  After inserting the silica gel I sealed up all the gaps in the camera with caulk and used hot glue to protect the resistor and exposed wire.

Pick a location for your camera that maximizes the viewing area, and insert your camera.  This is where your problem solving skills are going to really be needed.  There are so many different web cameras on the market yours will most likely be different from mine.  The next steps are how I installed my web camera, you should be able to modify them to fit your needs.

After finding a location to maximize the viewing area of the camera, I drilled a hole all the way through the bat house the diameter of the camera using a spade drill bit.

To protect the ends of the camera I cut out two pieces of wood  using the remaining wood from the roof piece (the 1" x 4" x 3' piece of wood).  The camera ends stuck out of the plywood a bit, so I used a Dremel to clear out a little bowl shape.  You can use any tools available to you for the job, like a chisel.

I caulked the edge of the opening and screwed on the protective ends I made.

Clamp on the 1" x 2"s and predrill holes for the deck screws.  The spacing for the holes isn't that big of a deal, just try to make a good seal.  Every 4" or so should do the trick.

Apply a generous amount of caulk onto the plywood.  This will fill up the gaps made between the channels and the frame.  Remove excess caulk.  I used white caulk here but a darker color would be better.  The idea is to keep out as much light as possible, thus creating a comfortable place for the bats to live.

Clamp on and predrill holes for the roof, apply caulk and screw onto bat house.

Carve out channel for the wire of your camera.  I used a Dremel for this, but again use whatever you have available.

Get out your primer and apply one coat to the exterior wood of the bat house.  At this point I have only drilled screws into the frame and back side of the bat house, and have only predrilled holes for the front of the house.  I would suggest inserting the front screws into the bat house after you are done priming and painting it.  In the future you may need to make adjustments to the camera or bat house and having access to the inside will be important.  If you insert the screws now primer and paint will fill the heads of the screws making it harder to remove them in the future.  When you do screw on the top portion of the bat house though, remember to again apply a generous amount of caulk to the frame beforehand.  Also remember the 1/2" gap in the front used for ventilation.

Get out the paint and apply two coats to the bat house, remembering to get the edges of the bat house.

I used a bent nail to keep the camera wire in place.  I also used the finger from a latex glove filled with silica gel crystals to protect the metal inside the USB plug.  Simply wrap a rubber band around the glove finger to secure it to the wire.  To test the covered plug I submerged it in water, and it repelled water rather well.

These are images from inside the bat house.  The top image is what things look like on the far side of the bat house.  The bottom image is what things look like furthest away from the camera in the bottom corner of the bat house.  So if a bat enters the bat house I should be able to see it as long as it isn't behind the small space behind the camera.