Penn State researchers looked at what happened after the poisoning and found that it did not work. People identified with this disease usually work where chook or bat droppings have accrued over a period of years or discover caves where bats lived. Despite the very small threat of harm to folks, histoplasmosis has been used to justify killing crows the place the nuisance of large roosts annoys people. Devices imagined to scare birds away with ultrasonic sounds don’t work. Pushed from their roost, crows generally transfer to the nearest similar web site. There will still be crows in the community, just not within the objectionable roost location.