 Additionally, bat populations in the Eastern U.S. have typically been monitored using surveys conducted in caves and mines in the winter, but small-footed bats hibernate in places that make them unlikely to be encountered during these surveys.As a result, numbers of small-footed bats counted in winter tend to be low and relatively variable compared to other species of bats.Many biologists believe the species is stable, having declined little in recent times, but that it is vulnerable, especially in its cave hibernacula.