12 Signs Your Basement Might Be a Bat Hangout

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Your basement is the warm underbelly of your home, a place for storage, laundry, or a secret getaway from the madness upstairs. What if you’re not the only one who thinks it’s a prime spot for peace and quiet? Those winged creatures of the night, bats, may also have come to the conclusion that your basement is the perfect refuge. However, being able to tell if your underground haven is hosting uninvited guests can be helpful, if you know what to look for.

Bats are great for the environment, namely insect control, but you don’t want them in your basement. From health concerns to the possibility of damage, knowing the signs of their existence will help you avoid problems down the road. Here are some telltale clues to let you know if bats are moving in to your basement.

Scratching or Flapping Sounds

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At night, do you ever hear faint scratching or what sounds like paper rustling? Bats are nocturnal and make subtle noises when they go about or take off. They’re not the sounds of rodents scurrying or your home settling. If the noises appear to be coming from the high corners or vents of the room, that’s a red flag.

Odd, Musky Odor

Just like a bat colony brings its own scent, that awful, pungent musky smell that doesn’t go away no matter how much you clean. The odor often comes from bat droppings (guano) mixed with the oils they produce. If your basement smells like it’s in a cave, you might want to check things out.

Poop That Doesn’t Look Like a Mouse’s

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Bat droppings, also know as guano, are small, dark, crumbly. They are frequently found in clusters near walls, or below high perches. Bat guano can break down into a type of dust when touched, unlike mouse droppings. Be cautious: Just disturbing it can give off harmful spores into the air.

Sighting One or More Bats

If you’ve seen a bat flying around your basement, chances are it did not fly there by accident. Bats are habitual creatures and do not wander without a group near. One bat could be the tip of the iceberg.

Dark Streaks at Entry Points

Look for dark, greasy streaks around windows, vents or in the cracks of the foundation. The oils from bats’ bodies make these marks as they go through tight spaces again and again. That’s their way of leaving fingerprints.

Walls or Ceilings With Small Openings

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They don’t need a grand entrance – a gap as small as half an inch will do just fine. Check your basement walls, vents and ceiling for any tiny openings they may use. You’d be surprised at how little space they need.

Nearby Areas Nocturnal Activity

If you have a lot of bats flitting around your yard in the evening, your basement may be the backup plan. If you have a rich bat population outdoors, it often means there is a nearby structure for them to live in. Look out for their flight patterns, they’re creatures of habit.

Evidence of Nesting Materials

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Bats don’t make nests like birds but they may leave behind any debris such as shredded insulation or soft material they’ve borrowed from your basement. The debris often is tucked away in corners or other out of the way spaces.

Clogged or Damaged Vents

Bats can enter through basement vents. Look for damage, such as bent or torn covers. If the vent looks intact, but there’s a little cluster of debris or droppings around it, chances are it’s being used as a gateway.

Discolored or Stained Walls

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Bats often roost in the same spot for extended periods, so their droppings, or urine may stain the walls or ceilings. The stains are generally brown, and streaks appear below where they sit.

Health Concerns Nearby

The Centers for Disease Control and Prevention (CDC) warn that bats can carry rabies or histoplasmosis. Although transmission risk is low, it’s not zero, especially if their droppings accumulated over time. Histoplasmosis from guano spores can cause a sharp uptick in respiratory issues in your household.

An Expert’s Confirmation

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“Bats like warm, dark spots where they feel safe, and a basement can be just that,” says Dr. Merlin Tuttle, a well known bat ecologist. If you’ve ruled out the previous signs, and aren’t sure, it’s a good idea to bring in a wildlife professional to confirm or rule out your suspicions.

Disclaimer: This list is solely the author’s opinion based on research and publicly available information.