by Mark and Selena Kiser
BCI and bat-house enthusiasts across the United States and Canada have collected nine years of data that can greatly improve your chances of attracting beneficial bats to your yard or farm. The latest survey from BCI’s North American Bat House Research Project highlights key factors for installing a successful bat house that will help you enjoy the benefits of bats.
One of the most frequently asked questions we hear is whether bat houses will work in urban and suburban settings, where habitats and landscapes have usually been altered severely. The results from our ninth annual survey are certainly encouraging: Bats were living in 50 percent of the houses our Research Associates monitored in urban and suburban landscapes.
And that success rate jumped to 68 percent (34 of 50 houses) when the bat houses were located within two miles of bat colonies living in buildings, bridges, or other human-made structures. A dozen urban/suburban bat houses had been installed as part of exclusion efforts to remove bats from buildings, and bats were using all 12.
Three of the most common species found in urban/suburban bat houses are little brown myotis, big brown bats, and Mexican free-tailed bats.
The 2001 bat-house survey was based on information gathered for 665 bat houses by 141 participants. Eleven species were confirmed using these bat houses, including — for the first time in our surveys — the endangered Indiana myotis. The total number of bats using the 345 occupied bat houses in which bats were counted was estimated at between 19,454 to 26,651.
Bats were using 393 of the 665 houses surveyed in 33 U.S. states, three Canadian provinces, and the Cayman Islands. That’s an overall success rate of 59 percent, regardless of design, construction, or placement.
Success rates go up sharply when BCI recommendations are followed and the houses have been up for at least one year. In this survey, more than three-fourths (233 of 304 houses) of bat houses that were installed prior to 2001 on buildings or poles and in groups of two or more were occupied. That clearly demonstrates the importance of proper mounting and multiple houses.
This survey again confirms that the best mounting sites for bat houses are buildings, chimneys, and other structures, such as dams, silos, and bridges. Although pole mounting is a more popular option, its success rate is slightly lower. Trees are generally poor mounting sites because of shade, obstacles, and predators.
The impact of mounting choices was clearly demonstrated by results of the survey’s 129 BCI Single Chamber/Small Economy Bat Houses. Overall occupancy was 46 percent, but this jumped to 67 percent when the small bat houses were mounted on structures rather than poles (47 percent success) or trees (zero occupancy).
Mark Kiser is Coordinator and Selena Kiser is Assistant of the North American Bat House Research Project.
Visit the Bat House Research Project web page. To see proven bat houses that BCI offers for sale, browse our online catalog!
