Bats are fascinating creatures that play important roles in ecosystems worldwide. They help control insect populations, reducing agricultural pest damage and the need for pesticides. Certain bat species are also vital pollinators and aid in seed dispersal, contributing to environmental health. Understanding their preferences and aversions is important for coexisting, especially when managing their presence in unwanted areas, emphasizing humane approaches.
Light and Noise Avoidance
Bats are primarily nocturnal, preferring dark environments. Bright lights disrupt their natural behaviors, making them vulnerable to predators. Artificial light also interferes with their echolocation, essential for navigation and hunting in darkness, by creating confusing shadows and reflections. This disruption makes it challenging for bats to hunt effectively and avoid obstacles.
Continuous bright lights can disorient bats and affect their foraging habits, as some lights attract insects, altering their usual hunting strategies. While most bats dislike light, some species may be attracted to lights that concentrate insects for feeding, though not for roosting. Bats also possess highly sensitive hearing and rely on high-frequency sounds for echolocation. Loud, unpredictable noises can disturb them, making an area less appealing for roosting or foraging.
Aversion to Certain Scents
Bats use their highly developed sense of smell for navigation, finding food, and communication. Strong, pungent odors irritate their sensitive olfactory systems, making an area undesirable. Scents like peppermint, eucalyptus, cinnamon, clove, menthol, garlic, and ammonia are disliked by bats. These natural scents, often in essential oil form, create an overwhelming aroma bats find unpleasant.
Mothballs, containing naphthalene, also produce a strong chemical smell that can repel bats. However, naphthalene is toxic and its use is discouraged due to health risks to humans and pets. The effectiveness of scent-based deterrents can be temporary, as their potency fades over time, and bats may habituate if it is the only deterrent used.
Humane Bat Deterrence
When bats establish roosts in unwanted areas, humane exclusion is the recommended approach. The primary goal is to encourage bats to leave safely without harm. This process begins by identifying all potential entry and exit points, which can be as small as 3/8 of an inch, by observing bats leaving at dusk. Once identified, most openings should be sealed, leaving one or a few primary access points open.
One-way exclusion devices, such as netting or tubes, are then installed over remaining active entry points. These devices allow bats to exit the structure but prevent re-entry. They should remain in place for several days to a week to ensure all bats have departed. After all bats have left, the final entry points can be permanently sealed.
Timing is important for successful and humane bat exclusion. Exclusion should be avoided during the maternity season, typically from mid-April or May to mid-August, depending on the region and bat species. During this period, flightless young pups are present and would be trapped and perish if their mothers are excluded. The most suitable times for exclusion are late August to October, after the young can fly, or in early spring, before maternity colonies form.
Using harmful methods like chemicals, toxicants, glue traps, or unproven ultrasonic devices is not effective and can be illegal. For effective and ethical bat exclusion, consulting with wildlife professionals is highly recommended.