Question

We think we might have bats in our attic. We haven’t actually seen any but we hear noises that could be bats or some other animal. Is there any other evidence we can look for to confirm bats? 

Answer

First thing I would suggest is that you contact a pest management professional, without delay. In our area, bats can only be removed from a home in early spring or in the fall when there are no young in the roost. A pro can conduct an inspection of your attic space and the outside perimeter of your home, looking for entry points around the roofline. If it’s bats, you’ll want to know that, but if you have some other animal in your attic, you’ll need to know that too, so control methods can be implemented in either case.

Here Are Some Clues That Indicate Bats

1) The most definitive sign that you have bats is actually seeing them flying in and out of a hole near the roofline. If you’re looking for them during the daytime, you may never see them. You need to time your viewing to coincide with the bats’ feeding schedule. They usually leave their roosts to hunt insects shortly after sunset. This early in the spring they may not be actively hunting yet.

2) Squeaking and rustling noises overhead in the ceiling area or inside walls, especially at dusk or on hot summer days. (Note: Flying squirrels and mice make similar noises.)

3) Look for holes or gaps around the roofline of your home. Common entry points are behind fascia boards, around sills, gables, eaves, vent louvers, or under loose flashing. Openings used by bats may be surrounded by dark smudge marks from oils in the bats’ hair. There may also be urine stains and droppings on the siding below the opening.

4) Look for bat droppings (“guano”) on the patio or ground below any openings found on the outside of your home, and in the attic or other area where you suspect they are nesting. Bat droppings are similar in size and shape to mouse droppings (black, elongate, about 1/3 inch long) but since they are mostly made up of insect parts, they are shiny and crumble when crushed.

5) If you have a large colony of bats, you might find stains forming on a ceiling inside your home from a buildup of guano and urine in the attic. This happens most often in older homes that do not have attic floor insulation.