Bat Shack

After  years of evicting bats & bat-proofing human houses I decided to build a BIG bat house and to try to entice some bats to move in.  The BAT CONDO (Jane) or BAT SHACK (Noa) incorporates some of the 'flaws' I've observed in human houses that make them appealing to bats. 

It's essentially a small (4' x 8') house on stilts with entrances at places that bats often use to enter a human dwelling -  things like loose flashing (e.g. around chimney), dormer windows (often open where they meet the main roof) and loose shingles or siding.  I didn't bother with a chimney on the Bat Shack, but it's common for bats to enter where a chimney passes through the roof of the house.

Here's how the construction of the Bat Shack went... 


Corner posts attached to post saddles set in concrete (approx 8' tall above the ground).

Two 4' X 8' sides and two 4' X 4' ends attached to a level 'skirt' to hold the stud walls in place.

Rafters & ridge pole installed...














Roof and sides/ends clad with plywood.  A small dormer was installed on both sides of the main roof.  Dormers are commonly used as entrances into human houses.

Shingles on and siding underway.  Black roof and black house-wrap (tar paper, here) should help with heat absorption and retention.  A maternity colony needs lots of heat, something that a small building might not be able to maintain. The red & white face on the dormer is just a red board with a white vent in it.

I had just enough siding left over from a renovation project to make the bat shack look pretty up-scale.











Shy on siding, the 'upstairs' was finished with board & batten (easy to cling to) and a false-door was added to the mix. Vents were added to the peaks at both ends of the house. 

How Bats Get In: 

Bat-sized gaps were left in the soffit at each corner of the house.  A small ladder was added at each doorway.

Two small entrances were made in the facia along the long sides (only one shown). There are built-in gaps underneath the roof of the dormer on both sides too.







INSIDE:

The inside is mostly open...bats often do warm-up laps in the attic at dusk just before they exit the building. It's lined with rough-cut pine (same as the board & batten) with narrow gaps between the boards so that bats can tuck in out of sight.  The bottom is open in this picture...










but, you can see it here.  Two plywood boards hinge downwards from the sides.  I envision piles of bat guano underneath the shack some day.  I've put down patio stones to keep down any vegetation...and to make guano- scooping easier ;)

The Finished Bat Shack

A final note:  Yesterday I heard the hiss of a bat as I closed the big barn doors. I was able to pry it out from its position behind the latch and introduce it to (hopefully) its new home just a few flaps away from where it was roosting.

First Tenant of the Bat Shack?  A male Big Brown Bat

How to Make a Simple Bat House

I've been making and selling 'BAT CHECK' bat houses for quite a while now (available at Living Rooms and Birds 'n Paws in Kingston, ON)  Here's a relatively easy model to build. You'll need some basic tools (handsaw, hammer, drill).  A table saw or 'chop' saw will make it even easier.  Count your fingers before and after to see that the numbers match!

To make one bat house you'll need:

1)  a piece rough lumber (3'  x 6 - 8 " wide x  3/4" to 1" thick).   (A rough surface gives the bats a good grip...smooth wood should be roughed up!)

2)  16 nails (2" galvanized,spiral)

A)  THE CUTS:   These are the lengths I use.  The board pictured is 6" wide.













BACK (15").  Note that I put 10 shallow, cross-cuts to form a 'ladder' for easy access. These are not necessary with a rough board.  Two 1/4" holes, one at top center and one at bottom center, can be drilled through the back piece before assembly.

SIDES (12").  Cut a sngle 12" piece & then  make a mark 5" from the end of one edge. Rotate the board and mark the opposite edge (same side!) at 5" too.  Connect the marks and cut the piece to yield two side pieces, each with a sloping top (fig. 1).

ROOF (9"+).  9" works if the board is 3/4" thick.  Go to 10" if the board is 1" thick.

FRONT (5").  My houses have a bat logo and a tag.  Blank is fine :)

BOTTOM (3.5").  This piece varies somewhat in length depending on the thickness of the board.  3.5" should do for most houses.



B)  ASSEMBLY:

I enclose the following illustrations with my Bat House Kits.  I'll add a few more details for you.

Fig. 2.  1st SIDE.  Align the 'pointed' end of one of the sides about 2" down from the top of the BACK piece.  Attach using two nails as shown.











Fig. 3. FRONT.  Tip the BACK onto its edge and align the FRONT as shown.  Make sure it's flush along the top edge (or the roof won't fit well) and along the front edge.  Nail as shown.

Fig. 4. 2nd SIDE.  Align with and attach (2 nails) the second SIDE to the FRONT piece first to avoid alignment problems. Next, align it along the BACK and add two more nails.

Fig. 5. INSERTING the BOTTOM.  Tip the bat house upside-down and rest it on the edge of a bench / table.  Slide the BOTTOM piece into the opening immediately behind the FRONT piece.  



















Fig. 6. CREATING the ENTRANCE.  Angle the BOTTOM piece towards the BACK piece to create a narrow doorway.  The bottom edge of the BOTTOM piece should be flush with the SIDE pieces and the opening should be about the width of your index finger (approx. 3/4").  Too big and other critters get in.  Too small and you might be lucky enough to get bees.

Fig. 7. ATTACHING the BOTTOM.  Place the bat house on its side and sight up the sloping BOTTOM to align the nails.  Use your fingers to wedge & hold it in place (this is the most finicky piece).  I usually put in a nail at the bottom of one side, then flip it over and repeat on the other side.  Thus you can pivot the top edge of the BOTTOM piece tight against the back of the FRONT piece and put in the remaining two nails.  Got it?  Got it!  :)

Fig. 8. ROOF.  Center the roof on the top of the SIDES.  Two nails in each SIDE completes the job!

There's a tweak you can incorporate if you have a table saw or plane of some sort.  If you look closely at Fig. 8 you'll notice that the top edge of the ROOF is beveled so that it fits snugly against the BACK. 
Find this angle using one of the SIDE pieces.  It's not crucial but it shows better craftsmanship (not to judge!)














DONE!  The bat house in the picture below is decked out with instructions and an envelope of bat droppings.  Some people think that the bat droppings are essential for success - giving the house a 'lived-in' (i.e. 'safe') aroma.  Bats actually show no preference for bat houses with or without the guano, so just put it up!



There is no ONE best location for your bat house because different species have different needs, as do bats of different sexes and of different stages in their life.  Some bats are exclusively tree-dweller, and are unlikely to use a bat house.  Pregnant females often seek out very warm (e.g. attic) housing during gestation and early rearing of the young, but once the young are volant (capable of flying) the females and the young-of-the-year (y.o.y.) look for cool places so that they can drop their metabolism to conserve energy and fatten up for hibernation.  Males often roost separately from the females (and y.o.y.) and stay in cooler day roosts.

I recommend attaching the bat house to a structure with a south or southwest exposure.  10' or so up keeps it out of reach of most pests (cats, squirrels). Buildings tend to be more secure and less exposed to the weather.  Try up under the overhang of your roof.  If you use a tree, make sure that there is sufficient space around the bat house for easy launch and return.  3 ' or so below the entrance will allow them to get flight speed when they head out at night.  When they return bats often 'touch-&-go' several times before committing to the return.  Seems to be a defensive behaviour just in case there's a predator awaiting their return.  

Anyway...I hope this is if use!

My next project is a BIG bat house - a bat condo, if you will - that will hopefully be suitable for a maternity colony.  More on this later.

Matt

The Bats are Back: Tips for keeping them out of your house.

The following article was published in Rural Delivery (www.countrymagazine.com) in 2006. 

After de-batting houses for 15 years or so I thought that it was time to pass on some of what I'd learned. 

I'm re-printing the article with permission from RD.

Some new photos have been added to better illustrate what's written. 

I hope you find this of use!

 

 

THE BATS ARE BACK:  Tips for keeping them out of your house.

 

Love 'em or hate 'em, the bats are back.  Many go unnoticed as they roost in backyard trees or comfy crevices.  Others make memorable impressions when they appear in living rooms.  Some cause problems as they fill attics with guano and night noises.  Rural and urban dwellers alike may encounter any number of bats over the course of a year and, along with snakes and spiders, they remain one of the least-liked of our wildlife.

 

This tiny creature is the Western Small-footed bat.  It weighs only

four grams - the weight of two dimes!  It is a blonde bat with a

black mask.

Bats begin to wing their way back to their summer flapping-grounds in early spring.  Some have spent the winter hibernating in nearby caves, mines and houses.  Others have migrated northward - like summer tourists - from warmer climates where they have been active all winter.  Most return to the same haunts year-after-year.  They set up territories around streetlights and skillfully prevent competitors from eating the insects that swarm there.  Others return to attics where they may have summered for 30 years.  Each species has a unique natural history and a different set of behaviours.  There is no such thing as a 'typical' bat.

 

Northern Red Bat (Lasiurus borealis). 

Tree-roosting species like the Red bat are

unlikely to show up in your house.

Until you've met some of the 20 different species found in Canada (nearly 1000 worldwide), it is tough to appreciate their differences.  Although all our bats are insectivorous, they range in size from the tiny Western small-footed bat - a four gram (the weight of 2 dimes) blonde bat with a black mask - to our largest, the 28 g, multi-coloured Hoary bat.  For reference, a dime weighs two grams, a quarter five grams, and a chipmunk around 60 grams.  Hoary bats have the largest wingspan - 40 cm (16 inches) of all Canadian bats.  A bats size is tough to estimate on the wing, and is often exaggerated.  Shadowy distortion and tricks of the brain, perhaps.  Intermediate-sized bats included Silver-haired, Red, Long-legged, Long-Eared (Northern, Eastern & Keen's), Fringed, Pipistrelle, Yuma and Spotted bats, among others.  This list includes world record holders - like the largest litter (Red bat), biggest ears (Spotted bat) and, quite possibly the longest-lived (Little Brown bat), thought the latter record is not easy to know. 

 

 



This Hoary bat (Lasiurus cinereus) is our largest, weighing 28 grams.

It is multi-coloured and has the largest wingspan of all Canadian

bats - 16 inches)

SHARING YOUR SPACE:

 

If you've shared your living space with bats, they are either Little brown bats (Myotis lucifugus) or Big Brown bats (Eptesicus fuscus).  In the Atlantic provinces it is usually the former.  Weighing in at just seven grams (equal to a loonie) these bats frequent buildings.  Males and females of this species behave quite differently, spending much of the summer apart before they meet in autumn to mate and hibernate.  Females store sperm for the winter and emerge pregnant.  They seek hot places, like attics, where they can stay warm throughout the day.  The warmth accelerates gestation and affords the time needed to give birth, nourish pups and bulk up for winter - a crucial adaptations where summers are short.  Human habitations have likely helped some species extend their ranges as far north as the Yukon and Northwest Territories and to Alaska.

 

Male Little Brown bats have a different plan.  They stay active at night but seek cool places - under siding, in wood piles, between bricks or under tree bark during the day.  Lower temperatures allow them to drop their body temperature, enter torpor (a short-term hibernation), conserve energy and fatten up for winter.  Females adopt a similar routine once the task of giving birth, rearing and weaning the pups is done.

 

A baby Little Brown bat (Myotis lucifugus).  In the Atlantic Provinces

 it is the breed that is most commonly found living in houses.

Born at about a quarter of the mother's weight (ouch!) a bat pup grows quickly on the milk it suckles from its mother.  As the put gets heavier, mom starts to leave it behind while she forages.  This is when the maternity colony may become conspicuous to the humans living below.  Hungry pups are noisy while waiting for mom, and even more boisterous when she returns.  After about four weeks, the young bats can fly and the colony may evacuate.  When the pup can feed itself - about mid-June to early July - mom's job is done.  Now both must conserve energy by abandoning the warm day-roost and seeking cool places.

 

A Little Brown bat flying inside and attic.  This bat weighs just

seven grams - equal to that of a loonie.

Young bats may be slower to adapt and occasionally get caught inside the house before they figure things out.  Unfortunately, frantic homeowners sometimes take after them with tennis racquets & brooms.  The bats won't intrude again if you either wait for them to land (often high on a curtain rod) and escort them bout in a tea towel, or direct them towards and open door by blocking their flight path with a towel.  Opening several doors or windows to create a cross-breeze will also show them the way out.

 

As autumn approaches, bats gradually make their way back to hibernacula to begin the cycle again.  Mortality is especially high in young bats (called young-of-the-year or YOY).  The proximity to humans, coupled with seasonal dangers, especially early or long winters, means that about half of the young bats don't survive their first year.  Disturbances during hibernation can also be disastrous.  Agitated bats waste precious body fat and may not survive until insects reappear.

 

Bats do, however, wake up throughout the winter.  As temperatures fluctuate, they may need to migrate inside the cave to find the ideal temperature and humidity.  It is not uncommon to see Big brown bats, which will hibernate in houses, awaken and fly about the yard or living room in mid-winter.  Christmas can also be a busy time.  Seems turning the thermometer up for grandma's visit and poking gifts into secret places isn't conducive to hibernation.  Others, low on fuel and desperate for grub, emerge in March and April - too early to be able to find food - and die from starvation.

 

EVICTING BATS FROM YOUR ATTIC:

 

 So, what can you do if bats have claimed your attic and you'd like to evict them?  First, don't resort to poisons, noxious sprays and home remedies like bright lights, loud noises, ultrasonic rodent repellers and mothballs.  None of these 'remedies' work.

 

 Bats, except non-volant young, leave your house every evening to feed and you can then bat-proof to keep them out.  Imagine your house as if it was a cardboard box.  If the perimeter of that box is closed, nothing will get in - except through doors and windows (check screens!).  If these openings are secure and the bats still get in, there are other entrances to attend to.  Little brown bats can squeeze through a gap the width of an index finger.  The most likely points of entry are where the roof meets the walls of your house (check all eaves, soffits, facia and gables for gaps) and around chimneys (check the metal flashing). 

Typical ways bats get in!

 

A day spent inspecting and sealing the edges of your hose is in order.   Do this before the bats give birth or after they move out - otherwise you risk locking the pups inside.  Use the bats to tell you how they get in.  Ask some volunteers to help watch your roofline at dusk on a clear night.  Noises in the eaves and swooping bats will reveal the main exits.  Guano stuck to a window or wall is also a telltale sign - bats often urinate and/or defecate before they land so the entrance is just above the mess.

 

After sealing up all but the final entrance or two, you can install a one-way chute and let the bats clear out on their own.  Snip off the end of a bread bag, affix it to the house (with staples, tape or caulking) and wait for the bats to flop out and fly away.  I use heavy plastic (vapour barrier) and fashion it into a tube that tapers away from the house.  Bats that want back in usually nose around the base of the tube and finally leave at dawn.

Looking up into a one-way chute fashioned from heavy

gauge plastic

 

A colony of 500 or more bats can be convinced to leave in just a single night or two - and you never have to see or touch even one.  The new exit can force some bats to stay in for a night or two and may bring several downstairs.  Be patient with the first group (wait about three nights) and escort the second group out as described above.

 

Big Brown bat attempting to get back into the house
after evicting itself.

Once you're convinced the bats are out, remove any remaining chutes, seal the openings and proceed with clean-up.  Bat droppings are not poisonous, as many people suspect.  They actually consist of chewed up insects.  As droppings accumulate, fungi and start to grow and their spores can cause problems.  Histoplasmosis - a respiratory ailment - is a nasty one. Guano can be vacuumed up (wear a tight-fitting mask) and used as a nitrogen-rich fertilizer  The smell from urine-soaked insulation may warrant removal and the use of a fogging -device (to spray a scented mist) will mask some of the musty odour. 

 

Problem solved!  If you feel pangs of guilt after the eviction, consider providing alternate accommodation for bats by erecting some bat houses.  Bats won't leave the attic to move into a bat house, but they may find solace there after the attic closes for good.  But that is a different story. 

 

(Matt Saunders has a B.Sc. and a B.Ed. from Mt. Allison University & a M.Sc. (in bat behaviour) from the University of Calgary.  He grew up near Truro, N.S., and starte a small business called Bat Check in 1990 to both educate people about bats and help them deal with bat problems.  he has evicted bats from many houses in the Maritimes and Ontario.  He currently resides in Seeley's Bay, ON with his wife Heather (a veterinarian) and a menagerie of dogs, cats, chickens, goats, sheep and a Newfoundland Pony.  Together they rehabilitate injured and under-nourished bats throughout the year.  Matt is currently the Head of Science at Kingston Collegiate and Vocational Institute where he has taught science, biology and environmental science for the past 15 years.)

Bat in the House?

Big Brown hanging on a screen.  Note the blue tag.

My number is on the Web as a bat rehabilitator & I've been fielding a lot of calls about bat sitings this year.  This blog will be devoted to bat stuff...including some general information about WHAT TO DO if you find a bat in the house.

 

First...every bat that I've received from somebody over the fall or winter has been a Big Brown Bat (Eptesicus fuscus).  They are little, as far as animals go, but they're the 2nd biggest bat species in Canada and the only one that'll hibernate in your house



Big Brown Bat...note the bare nose.

during the winter.  The picture below shows the characteristic bald patch around the eyes and nose.  They have a puffy, hairless nose, unlike some of the other bats that might nose about your place in the spring and summer. 

 

I'll focus on Big Browns for this blog, as they're the ones you'll most likely encounter.

 

By hibernation time, BB's have reached adult size (thumb-sized body & wingspan of about 30 cm).  In order to survive the rigours of hibernation, a bat needs to be FAT and relatively undisturbed. Low body mass and disturbances mean they must awaken & move about and in the process burn precious fuel.  It's tough to know whether a bat is at a healthy weight without checking...some of the bats I receive are perfectly healthy & are released, while others are underweight and unlikely to make it 'til spring.

 

So, you have a bat in your house...

 

Baby Little Brown Bat

If it's early spring or summer, it could mean that a bat (or bats) are using your house to set up a maternity colony.  Females use the warmth of the attic (often) to speed up gestation.  These colonies can be big, with several hundred females, or small.  A quick scan for bat droppings or activity in the attic may reveal such a colony.  They're often noisy...especially once the young are born....and can be smelly, depending on the population size.  I've been knee-deep in bat guano in some attics...and even have some bat-urine stalactites from one house.  Anyway...I'll add an article that I wrote called, 'The Bats Are Back,'  in case you need more info on how (or if!) you want to deal with a maternity colony.

 

Once the bat pups have been weaned and they're flying and feeding on their own, the next big job is to fatten up for winter.  To do this the females (and young-of-the-year = YOY) abandon the attics (too warm!) and seek daytime lodging somewhere cool.  This enables them enter torpor (slows metabolism) and conserve energy and thus increase their body mass in prep for hibernation.  People with obvious maternity colonies often notice that things get quiet OR that bats start to move down in to the walls, and sometimes show up in basements later in the summer.   Young bats make lots of 'mistakes' when they first learn to fly and will show up in all kinds of awkward places at this time. 

 

BB's hibernating in a cave

 

Now it's time to hibernate.  All bats in Canada are insectivorous (Lots of bats arrive in a box with banana slices and peeled grapes.  I blame Stellaluna!) so when the insects are done bats either migrate south (some species never hibernate) or find a spot to hibernate.  The perfect spot is cool (just above freezing), humid, dark and quiet.  Caves and mines can provide this, but BB's will sometimes find what they need inside your house. 

 

Most houses are porous to bats at some level, but not all houses are suitable for a bat to make it through 'til spring - hence the mid-winter visits.  Imagine that a bat has moved into your house.  Insulation keeps heat in so outside of the insulation - but still inside the shell of your house - may provide lots of suitable places to hibernate.  Attics are typically too cold - unless the winter is mild or you have poor insulation - and too dry But, somewhere between the roof line and the basement there could be suitable conditions.  Homeowners can sometimes hear bats (mice? rats?) moving up and down inside the walls during the winter. Once a suitable location has been found the bat drops its temperature and begins to hibernate.  There are, however, several things that can wake them from their sleep:

 

DISTURBANCE:  I get a lot of calls around Christmas and other holidays when people are home, hiding presents in weird places, snooping around in attics, turning up the heat for gramma, etc...

 

BODY CONDITION:  Mortality in the YOY is generally high.  They may have had only a few months to fatten up, so they get hungry and must come out of hibernation to find food...of which there is none.  I get lots of emaciated bats in Jan. to March, before insects are abundant again.  Old bats will also expire at some time.  It's hard to tell the age of a bat except for in the 2 or 3 months after they are born.  Disease (e.g. White-nose Syndrome) can also deplete their reserves as they sleep, essentially starving them).

 

WEATHER:  Most of my calls pour in after a dramatic change in the weather.  A cold snap means bats may have to move closer to the warmth in your house.  A warm spell means they have to move away from the heat.  Listen for noises in your house after such changes.  The fall and early winter of 2014 has been reasonably mild and I've had many calls from people finding bats on their house, under their decks, etc.  Ambient temperatures were just about perfect for hibernating outside.  It's important to realize that bats don't necessarily sleep  peacefully from autumn until spring...they must move when needed to maintain the right environment.  I've seen one flying down Frontenac St. in Kingston in the midst of a snowstorm.

 

So, What do I do if I find a bat in the house?

 

If it's summer time, see the article on bat relocation in 'The Bats are Back' (next blog).

 

In the winter...

 

First, don't be surprised if it can't fly.  If a bat gets into your living space and has time to just hang out it will eventually lower it's body temperature to that of the room - say 20 C or so.  At this temp. it physically cannot fly.  It'll still be responsive and may hiss and bare its teeth (impressive!)& it may even stretch its wings, but it cannot fly.  In order to do so it will have to warm itself up to about 37 C which it does by shivering.  If you disturb it and then watch, it'll start to shiver slowly at first and then violently until it gets warm enough.  This might take 15 minutes or more, and then it'll get what I call the "launch Look" during which it blasts out sonar calls and THEN it will fly.  Before it warms up you can CAREFULLY wrap it in a dish towel or grip it gently with heavy gloves and place it outside...even if it's cold.  Place its belly against a tree or a brick building.  Be sure that it can cling to the surface and make sure it's inconspicuous to protect it from cats, birds, etc.   If it's daylight, the bat might stay until dusk, but when it warms itself up it will likely go back to where it came from...likely back into your house.  I'll be unlikely to make the same mistake twice.  If, however, the bat stays where you placed it for over a day, it may need more attention.

 

Hanging High on the wall...at Christmas!

If it doesn't fly after a day or so...or if it shows signs if injury (blood, tears in the wing / tail, bones at odd angles or asymmetry in the way it hangs), it will need help.  A 'normal' looking bat could be underweight for a variety of reasons (see above) and will need help.  Contact your local wildlife rehabilitation centre to see if they work with bats.  Bats are considered a 'rabies vector species,'  so not all centres will be able to receive them.  In most cases, you'll have to deliver the bat to the centre, unless some other arrangements can be made.  Some have 'flying angels', people who volunteer to bring injured animals to a care facility.  KEEP THE BAT IN A COOL, DARK, QUIET place if you've decided to take it somewhere.  I transport bats in small, cotton pouches that are tied at the top (similar to a small pillow case) but a cardboard box with a tight fitting lid and some fabric onto which it can cling or under which it can hide will serve.  Do not attempt to feed the bat (see the red bits below!).  You can put in a small water dish, but it is unlikely that it will drink on its own.

 

If it's flying normally you can wait for it to settle...they often land high, on curtain rods, etc. when given a chance and then follow the directions above OR open several windows, a door, etc. and hold up a towel (a soft, sonic and visible barrier) as it flies by to direct it towards the opening.  This can be fun.  Most common 'mistake' is to see a bat flying and to leave the room.  You might spend weeks not knowing where it is, or if it has left.  People often claim that a bat is diving or swooping at them in the room, but if you sit near the wall and stay low, you'll see that it will fly up near the walls, touch-n-go with its belly and claws (and perhaps hang) and then, to get flight speed it must 'swoop' at the centre of the room before another wall looms.  BB's are nimble, fast flyers and will have trouble making turns in a small room.  You could use this to your advantage.  Keep pets out of the room!

 

In every case, make sure that you don't get bitten!

That's a whole different story...one in which the local health unit must be notified, the bat must be killed (even if it's healthy...you can only tell by removing its brain...bats don't survive a rabies test) and you'll have to have post-exposure shots until the word gets back on the bat  DONT put yourself in a position where you could be BITTEN!  Got it?