The installation of an artificial roosting structure, commonly known as a bat house, is an effective measure for local bat conservation. These specialized shelters mimic the tight, dark crevices bats seek out for safe harbor, particularly for raising their young. Providing a bat house offers alternative habitat for species facing loss of natural roosts and encourages the presence of natural insect predators near your property. Success in attracting a colony hinges on meticulous preparation and placement, transforming a simple wooden box into a functional, heat-retaining sanctuary.
Optimal Site Selection for Bat Houses
The location chosen for mounting the structure is the most important factor determining bat house occupancy. Bat houses must receive substantial solar heating to maintain high internal temperatures (85°F to 100°F), which is necessary for maternity colonies to thrive. To meet this thermal requirement, the house should face South or Southeast, ensuring it receives a minimum of six to eight hours of direct sunlight daily.
The preferred mounting height is between 12 and 20 feet above the ground, allowing bats a clear, unobstructed flight path. A pole or post mount is often the most successful choice because it can be placed freely in an open area, away from tree canopy that casts excessive shade. Mounting a bat house directly onto the side of a building, especially brick or stone, is also effective as the structure absorbs and radiates heat back into the box.
Mounting on a tree is discouraged because surrounding branches provide too much shade, and the rough trunk allows easy access for potential predators. Bats also prefer roosts situated within a quarter to a half-mile of a permanent water source, such as a pond or stream. This proximity ensures a steady supply of insects and a convenient place for bats to drink.
Step-by-Step Mounting Instructions
Before mounting, proper preparation is necessary to ensure the house’s longevity and thermal performance. All exterior seams should be sealed with high-quality caulk to prevent drafts and moisture intrusion, which can chill the roosting chamber. The exterior should then be painted or stained a dark color, such as black or dark brown, using two coats of water-based paint to maximize solar heat absorption.
For a secure pole-mounted installation, use a pressure-treated wooden post or two galvanized metal pipes joined together. The post must be sunk three to four feet into the ground and stabilized with concrete to withstand wind and weather. The bat house is then attached using robust mounting brackets and lag screws or U-bolts, depending on the pole material.
When attaching the house to a building, use weather-resistant screws that pass through a mounting board and secure directly into the solid structure, avoiding siding only. Use a ladder rated for the required height and have at least two people for the lift and attachment process due to the house’s weight and elevation. Ensuring the area beneath the house is clear of obstacles provides the bats with the necessary drop space to take flight.
Seasonal Timing and Encouraging Occupancy
The ideal window for installing a bat house is during late winter or early spring, before bats emerge from hibernation and begin scouting for summer roosts. This timing allows the house to weather a full seasonal cycle, dissipating any lingering chemical odors from the paint or caulk. Installing the house before the maternity season (May through August) gives pregnant females the best opportunity to find and settle into the new habitat.
New bat house owners should manage their expectations, as occupancy can take anywhere from six months to two years, or occasionally longer. Bats are cautious creatures and must determine the new structure is safe and thermally suitable before forming a colony. Patience is the primary requirement for success once the placement guidelines have been followed.
Do not attempt to use commercial lures, guano collected elsewhere, or recorded bat calls to attract tenants, as these methods have not been scientifically proven to work. The most reliable attraction method is correct placement, ensuring the house meets the bats’ requirements for temperature and safety. Once installed, the house should not be disturbed during daylight hours, especially in the summer, to avoid causing stress to potential residents.
Ongoing Care and Troubleshooting
Bat houses require minimal maintenance because they are designed to be self-cleaning with an open bottom, allowing guano to drop to the ground. An annual inspection, ideally conducted during the winter when bats are absent, is recommended to check for structural integrity. Look for cracked seals, warped wood, or loose hardware, and re-caulk seams or re-stain the exterior to maintain the thermal seal.
A common issue is the presence of wasp nests, particularly from paper wasps, which build gray, honeycomb-shaped nests inside the chambers. While paper wasps can sometimes coexist with bats, their nests should be scraped out during the off-season using a long, thin rod to prevent them from taking up roosting space. Yellow jackets and hornets are aggressive and will cause bats to abandon the house, requiring immediate removal of their nests in the cold season.
If a bat house remains empty after several years, a minor adjustment may be warranted, such as changing the paint color to a darker shade or ensuring it receives more direct sun exposure. The first sign of successful occupancy is the appearance of small, dark guano pellets accumulating directly beneath the house, confirming the new tenants have arrived.