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Bat Droppings
Bat Droppings  
What we originally thought was mouse/rat droppings turns out to be bat poop.  (Although, I'd never seen mouse/rate droppings stuck to a wall near the ceiling) I snapped the attached picture last evening around 6 PM.  Live in San Francisco.  The garage is completely open on the back end of this 4-unit building - it's a drive-thru to carport, so no possibility of closing it off.
These little devils (assuming that there is, in fact, more than the one in the pic) have parked themselves in quite a few places around the garage, as evidenced by the guano still stuck to the walls (near the ceiling), and directly below on the floor.

While I do understand that most bats are, in fact, beneficial creatures, I also know they can carry rabies & hantavirus, among other things.

1.  What, if anything, should we do about this?
2.  Should we be concerned about the guano?  There's one spot where people are walking thru it pretty much all the time (see bat droppings pic)

Thanks in advance for whatever advice you are able to offer.

Hi Carey

The only way to permanently solve a bat infestation at any structure is to eliminate all entry-points or potential entry-points that are available to the bats. So the fact that the garage is a drive-through and is open all the time makes it impossible to bat-proof. You might have some success if you were to have the building bat-proofed and then install cloth or plastic drive-through doors on the garage doors. These would be vertical strips of cloth or plastic approximately 8-10" wide that are fastened to the top of the garage door frame and left hanging loose at the bottom. It would be a lot like the cloth strips that your car passes through when it moves through an automatic car wash. Of course you would have to find someone to fabricate these doors as I don't believe such a product is commercially available. So the simple answer is- bat-proofing your garage would be a large, expensive project and you'd need a very skilled, open-minded contractor to perform the work.
As for the bat guano, there isn't much to worry about. In the vast majority of cases bat guano is only hazardous when it is disturbed (swept with a broom). When this happens tiny particles called spores form a dust cloud that is sometimes invisible. When humans inhale these spores they can contract a dangerous respiratory disease. However in 99% of cases this is only possible when indoors, in a tight, poorly-ventilated area such as an attic.
Thankfully, when bat guano is outdoors it is usually harmless. I would still recommend waiting for a windy day to cleanup any guano outside your garage. That way any dust from the guano is immediately carried away in the wind.

Good luck and I'm sorry I couldn't give you an easy answer or a quick-fix. Yours is truly a tough problem to solve.

Matt Grady
BatGuys Wildlife Service

Pest Control

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Matthew Grady


Any and all questions regarding bats in houses, attics and chimneys. All questions in regards to bat guano in houses and removing bat guano from attics. All questions regarding squirrel removal, raccoon removal and skunk removal.


I am a Wildlife Control specialist with many years experience in the field. I specialize in bat removal and exclusion services.

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