Fresh bird droppings on surfaces such as sidewalks and windowsills have not been shown to present a health risk for histoplasmosis because birds themselves do not appear to be infected by H. capsulatum. Rather, bird manure is primarily a nutrient source for the growth of H. capsulatum already present in the soil. Unlike birds, bats can become infected with H. capsulatum and consequently can excrete the organism in their droppings. Of greater risk, is disturbing and creating airborne dust in areas suspected to contain H. capsulatum, such as; soil under trees where blackbirds have roosted for 3 or more years, heavy habitat of pigeons and bats, and poultry houses with dirt floors.