Bat guano is the term for bat feces, and its presence is a common sign that bats may be roosting in an area, such as an attic, chimney, or shed. Identifying these droppings is important, as they can signal potential structural damage or pose a health risk. Correct identification is necessary because guano can easily be mistaken for rodent droppings, which require different mitigation strategies.
Physical Characteristics of Guano
Bat guano typically appears as small, dark, elongated pellets, measuring about 1/8 to 1/4 inch in length. Fresh droppings are usually dark brown or black, but they lighten to a reddish-brown or gray color as they dry out. The pellets often accumulate directly beneath the bats’ roosting spot, forming distinct piles rather than being scattered randomly.
The unique texture of guano results from the bat’s diet, which is primarily insects. Insectivorous bats consume hard-shelled prey like beetles and moths. The undigested, shiny fragments of insect exoskeletons, known as chitin, are visible in the droppings, giving the guano a distinctive sparkly appearance and contributing to its crumbly nature.
How to Distinguish Bat Droppings from Rodent Feces
Distinguishing guano from mouse or rat feces is important for determining the source of an infestation. While the two types of droppings look similar, their differing diets result in a major textural difference. Guano, composed largely of fragile insect fragments, will crumble easily when crushed.
When bat guano is crushed, it disintegrates into a fine, powdery dust, often revealing the shiny insect parts. Rodent droppings, in contrast, are formed from fibrous plant matter and are uniformly solid, hard, and resistant to crumbling.
Rodent droppings are typically scattered along pathways, while guano is concentrated in piles directly underneath a bat’s roosting location.
Health Risks Associated with Guano
The primary health concern linked to bat guano is Histoplasmosis, a respiratory infection caused by inhaling the spores of the fungus Histoplasma capsulatum. This fungus thrives in the nitrogen-rich environment created by the accumulation of dried bat or bird droppings. The risk of exposure is highest when dried guano is disturbed, causing the microscopic spores to become airborne.
Symptoms of Histoplasmosis often appear as a mild flu-like illness, including fever, coughing, and fatigue. The infection can become severe, particularly for individuals with weakened immune systems, affecting the lungs and occasionally spreading to other parts of the body. Because the fungal spores are invisible, precautions must be taken to avoid inhaling any dust created from disturbing the droppings.
Safe Removal and Cleanup
Safe removal of bat guano requires a rigorous protocol to prevent the aerosolization and inhalation of fungal spores. Protective gear is necessary, including a respirator with an N95 filter or better, protective clothing, and gloves. Avoid dry sweeping or using a standard household vacuum cleaner, as these actions will launch spores into the air.
The correct method involves lightly misting the guano with water or a diluted bleach solution before removal. This dampens the material and weighs down the spores.
Once dampened, the droppings can be scooped up with a shovel or dustpan and double-bagged in heavy-duty plastic for proper disposal according to local hazardous waste regulations. For large or deep accumulations, or in poorly ventilated areas like attics, contacting a professional cleanup service is highly recommended.