Which is not evidence of bat infestation?

Chirping noises from a chimney are not typically considered evidence of bat infestation. While bats do produce various vocalizations, particularly high-pitched sounds, their primary noises are more akin to squeaks and clicks that result from their echolocation abilities. In contrast, chirping sounds are generally associated with birds.

Other options clearly indicate signs of bat presence. Squeaking noises from ceilings and walls could suggest bats roosting or moving within those spaces. A small opening with dirty staining likely indicates a point of entry where bats have been active, as their presence often leads to the accumulation of droppings and oils. Similarly, droppings found on sidewalks or ledges are a clear sign of bat activity in the area, reflecting feeding and roosting behaviors. Thus, chirping sounds would not be a reliable indicator of bats, as they are more closely linked to avian species.