Bat droppings and squirrel droppings look different enough to tell apart once you know what to check. The fastest test: pick up a dropping with a tissue and gently crush it between your fingers. Bat droppings crumble into a fine, sparkly powder. Squirrel droppings hold their shape and feel fibrous, more like compressed plant material. That single test is usually all you need, but size, shape, location, and health risks also differ in important ways.
Size, Shape, and Color
Bat droppings are roughly the size of mouse droppings, similar to grains of rice, and are dark brown to black. They’re distinctly pinched at the ends and often look segmented, almost like tiny linked pellets. The defining feature is what’s inside them: because bats eat insects, their droppings contain fragments of crushed exoskeletons. Those hard, shiny flakes catch the light and give bat guano a faint glitter when you break it open.
Squirrel droppings are noticeably larger, typically around 3/8 inch long, and barrel-shaped with rounded (not pinched) ends. Fresh ones are dark brown and slightly soft. They lighten to tan or gray as they dry out. Since squirrels eat nuts, seeds, bark, and fruit, their droppings are dense and fibrous with no shiny material inside. They’re closer in appearance to rabbit pellets than to anything a bat produces.
The Crumble Test
This is the simplest field identification method. Roll a dropping between your thumb and forefinger through a tissue or while wearing gloves. Bat droppings disintegrate under very little pressure into a dry powder that may shimmer in sunlight. That shimmer comes from the chitin in insect exoskeletons, which survives digestion and shows up as tiny reflective flakes.
Squirrel droppings resist crushing. Even older, dried-out squirrel pellets hold together and feel grainy or fibrous rather than powdery. Rodent droppings in general, whether from squirrels, rats, or mice, are harder and more compact than bat guano because they’re made of digested plant fiber rather than insect parts.
Where You’ll Find Them
Bats and squirrels both end up in attics, but their droppings show up in different patterns. Bats roost in clusters and defecate from their roosting spot, so guano piles up directly below where they hang. You’ll find accumulations on attic floors, in wall recesses, and sometimes on the exterior of the building beneath entry holes. Bats also urinate and defecate as they fly out of a roost at dusk, which creates scattered spotting and staining on siding, windows, patio furniture, and cars parked nearby.
Squirrel droppings tend to be more spread out. Squirrels move around an attic rather than hanging in one spot, so their pellets are scattered along travel paths, near nesting areas, and around food caches. You’re more likely to find squirrel droppings mixed into disturbed insulation rather than in a concentrated pile. Squirrels are also active during the day, so if you hear movement in the attic during daylight hours and find rounded, firm pellets, you’re almost certainly dealing with squirrels rather than bats.
Health Risks of Bat Droppings
Bat guano carries a serious respiratory risk that squirrel droppings do not. The fungus Histoplasma capsulatum thrives in damp soil enriched by bat (and bird) droppings. When dried guano is disturbed, fungal spores become airborne and can be inhaled. The resulting infection, histoplasmosis, ranges from mild flu-like symptoms to chronic lung disease with weight loss, bloody cough, and difficulty breathing. In severe cases, it can cause acute respiratory distress syndrome, where fluid fills the air sacs in the lungs and cuts off oxygen delivery to the blood.
Many people exposed to the spores never develop symptoms, but the risk increases with the volume of guano and how enclosed the space is. An attic with years of accumulated bat guano in still air is a high-risk environment. Caves, old barns, and chicken coops are other common sites where the fungus grows.
Health Risks of Squirrel Droppings
Squirrel droppings don’t carry histoplasmosis, but they aren’t harmless. Squirrels, like other rodents, can transmit leptospirosis through urine-contaminated soil or water. They can also carry tularemia, a bacterial infection caused by Francisella tularensis that spreads through contact with infected animals, contaminated soil, or tick bites. Salmonella is another possibility with any rodent feces.
The risk profile is different from bats. With squirrel droppings, the danger is primarily from direct contact or ingestion rather than from airborne spores. You’re less likely to develop a serious illness from briefly encountering squirrel pellets, but prolonged exposure to a heavily contaminated attic still warrants protective measures.
Safe Cleanup for Each
For bat guano, especially large accumulations, the cleanup process is more involved. The key principle is never to sweep or vacuum dry guano, because that launches spores into the air. Wet the droppings first with a disinfectant solution of one part bleach to ten parts water, then wipe them up with a soaked mop, sponge, or rag. For small, localized deposits, gloves and a bleach solution may be sufficient. For larger amounts in enclosed spaces like attics, the recommended protective gear includes a respirator fitted with HEPA filter cartridges, nonabsorbent gloves (nitrile or vinyl), eye protection, disposable coveralls, and shoe coverings. Respirators require proper fit-testing to work correctly.
For squirrel droppings, the same general approach works: dampen before removing, wear gloves, and disinfect the area afterward. When squirrels have contaminated attic insulation extensively, full insulation removal and replacement is sometimes necessary. After cleaning, sealing gaps in the attic floor with expanding foam helps isolate the attic from living spaces below and prevents future contamination from reaching the rest of the house.
With either animal, avoid touching droppings with bare hands. If you’re dealing with a large or long-established infestation, professional cleanup reduces your exposure to pathogens you can’t see or smell.
Quick Comparison
- Size: Bat droppings are rice-grain sized. Squirrel droppings are roughly twice as large.
- Shape: Bat droppings are pinched at the ends and segmented. Squirrel droppings are barrel-shaped with rounded ends.
- Texture: Bat droppings crumble to sparkly powder. Squirrel droppings stay firm and fibrous.
- Contents: Bat droppings contain shiny insect fragments. Squirrel droppings contain plant fiber.
- Pattern: Bat droppings pile up beneath roosting spots. Squirrel droppings scatter along travel routes.
- Primary health risk: Bat guano poses an airborne fungal risk (histoplasmosis). Squirrel droppings carry bacterial risks through contact (leptospirosis, tularemia).