What indicates an inactive vertebrate pest burrow?

An inactive vertebrate pest burrow is typically identified by physical signs of disuse. A partially collapsed burrow indicates that it has not been maintained or used for a period of time. This collapse occurs because the structural integrity of the burrow is lost when the resident pest is no longer present to keep it clear and open. Natural erosion or settlement can also cause the walls of the burrow to cave in, signaling inactivity.

Other options do not indicate inactivity effectively. Fresh tracks around a burrow imply recent activity, indicating the presence of the pest. A burrow with no signs of disturbance may still be active, as it might simply be that the pest has not recently used it but could return. Similarly, a wide-open entrance suggests potential ongoing use, as pests usually keep their burrows accessible for quick entry and exit. Therefore, the characteristic of being partially collapsed is a clear marker of an inactive burrow.