They may be cute and extremely beneficial, but bats have a nasty reputation for being susceptible to rabies. Of course, this reputation is undeserved, but the poop does carry other health concerns.
Knowing how to identify and safely remove their poop (also known as guano) is vital to both confirming the presence of bats and keeping your family safe from disease.
What Does Bat Guano Look Like?
There are a lot of popular misconceptions about what guano looks like. In games and media, it’s usually depicted as greenish, slimy, and abundant. But real guano is very different.
Shape and Size
Guano is generally oval in shape and segmented. In fact, it’s commonly mistaken for signs of a mouse infestation. Depending on the species, fresh droppings will range from 0.125 to 0.5 inches in length, which is about the size of a grain of rice.
For some species, the guano is straight, while others may be curved or have a bulge. This makes species identification much easier.
Color and Consistency
Bat feces is usually black or nearly black in coloration. It’s extremely dry and fragile, crumbling at even slight pressure. Unlike many other critters, there’s no white component to the poop.
What’s In It?
While there are species that feed on fruit or even blood, most common bats in the US are strictly insectivores. This results in fragments of shiny exoskeleton throughout the poop.
Not only does this make them stand out from rodent droppings, but may account for the “green” color often attributed to guano in media, as the fragments refract light at certain angles.
Smell
Guano is infamous for its strong, musky odor. While finding a single dropping might not be that powerful, the collection directly under a roost can be overwhelming.
If you’ve ever been to a bat exhibit at the zoo, you’ll probably understand.
Location
As mentioned, guano is most commonly found in piles directly under where the bats roost. However, it can also cause stains on walls beneath entry points or be found isolated in your yard from aerial bombing.
Bat vs Other Animal Droppings
| Animal | Size | Shape | Contents | Odor |
|---|---|---|---|---|
| Bat | 1/8" to 1/2" long | Tubular, segmented | Insect debris for insectivores, seeds for fruit bats, or dried blood for vampire bats | Pungent, musky |
| Chipmunk | 1/4" to 3/8" long | Cylindrical with tapered ends | Berries, seeds, plant matter | Mild, earthy smell |
| Coyote | 3-5" long, 0.75-1.5" diameter | Twisted rope w/ segments, tapered ends | Fur, bones, seeds, grass, nuts, fruits, berries | Variable, can be strong |
| Domestic Cat | 1" long, 1/2" diameter | Segmented | Less likely to contain food remnants | Pungent, distinct odor |
| Fox | 2-3" long, 1/2" diameter | Rope-like or twisted, segmented, tapered ends | Fur, bones, or other prey remnants | Slightly pungent |
| Goose | 2-3" long, 1/2" diameter | Tubular, may spread due to liquid urates | Grass and other plant matter, berries | Usually mild |
| Mouse | 1/8" to 1/4" long | Cylindrical with tapered ends | Fruit, seeds, insects | Slight musky |
| Opossum | 1-2" long, 3/4" diameter | Elongated, tubular, slight curve | Fruits, insects, and other soft foods | Mild odor |
| Rabbit | Less than 1" | Round pellets | Plant matter | Mild odor |
| Raccoon | 2-3" long, 3/4" diameter | Tubular, segmented | Seeds, berries, garbage, or debris | Mild odor |
| Skunk | 1-2" long, 1/2" diameter | Tubular, segmented | Seeds, insect parts, fur, or feathers | Slight musky |
| Snake | 1-12" long, 0.4-1.6" diameter | Smooth, oblong, soft or runny | Fur, bones, feathers, or other prey remnants | Faint odor to pungent |
| Squirrel | 3/8" long, 1/8" diameter | Oblong pellets | May contain traces of wood or nuts | Mild, earthy smell |
Are Bat Droppings Dangerous?
Guano is a mixed bag. On the one hand, the nutrient-rich droppings make for an amazing fertilizer. On the other, there’s a risk of two nasty diseases from wild bat droppings. Interestingly enough, bat droppings are far less likely to cause an allergic reaction than mouse droppings and similar fecal matter.
Parasites
Due to the dry nature of guano, parasites are unlikely to survive. Additionally, bats very rarely carry parasites on their bodies, so the risk of ticks and other little nasties being dislodged near the poop is minimal.
That said, the presence of guano or other feces can attract a whole host of other pests, such as roaches, flies, or even beetles.
Bacterial and Viral Diseases
- Histoplasmosis – One of the nastiest things you might encounter in bat or bird droppings, histoplasmosis is caused by inhaling fungal spores. While often asymptomatic, it can be deadly to infants and those with immunodeficiencies.
- Rabies – The rabies virus causes an incurable neurological disease and can survive under incredible conditions. Less than 0.1% of all bats actually contract rabies (and even bats in contact with humans and livestock have less than a 3% chance), but it’s better to be safe than sorry if handling guano.
Odor and Property Damage
Considering how dry guano is, one might think it doesn’t cause much damage. However, its brittle nature means staining walls and floors is common. Additionally, bats do urinate, which can cause smears and potentially liquify crushed feces. This latter effect may be where the myth of guano being a slimy mess comes from.
What To Do If You Find Bat Droppings
If someone in your household finds bat guano on your property, here’s what I typically recommend:
- Keep pets and children away from the area to prevent accidental contact with the droppings.
- If there are bats present, DO NOT attempt to clean until you have successfully removed the bats, either through exclusion devices or hiring a professional.
- Wear disposable gloves and clothing that covers your skin. Be sure to wear a mask and eye protection to reduce the risk of contracting histoplasmosis.
- Carefully remove the guano, trying not to break it up any more than necessary.
- If you plan to use the guano for fertilizer, bag it up until ready and mix it into either compost or your planting soil. Remember, fungal spores can still be present, so you may wish to treat it with a fungicide before using.
- In the event you don’t wish to use it for gardening, carefully dispose of it in a Ziploc or similar sealable bag.
- You may wish to vacuum the area. Using a steamer is best for this task, but a regular vacuum cleaner will still get up any tiny fragments.
- Sanitize the area using Clorox wipes, a bleach spray, or a similar product that’s safe on the affected surfaces.
Morgan is a certified entomologist and pest control consultant and a member of the National Pest Management Association.
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