Roosting and nesting in abandoned buildings like silos and barns, and in tree cavities and thick tree areas, barn owls are a nocturnal rodent removal system. They eliminate rats and mice using their low light vision but they have the best ability of any animal to hunt by using sound. The barn owl does not hoot like other owls, instead it lets out piercing shrieks or a raspy hissing sound. Known in some places as a death owl or ghost owl several traditions consider them an evil omen or bad luck. The truth is they help humans in rodent control but the use of rat poisons has a negative effect on their population. Often the poison does not kill the rats for several days and the owls eat the rats causing them to die slowly from unknowingly ingesting the poison that was in their prey.