Bat Houses

Bat Houses
August 27, 2018 Christina Mullin



Bats are a natural pest control. Did you know that some bat species eat an incredible number of mosquitoes, as many as 1,200 in an hour of feeding! Bats are also critical pollinators of seeds and fruits that we eat.

Once your bat house is constructed or purchased, it’s important to choose an area for installation that has the best chance of attracting bats. How and where you mount your new bat roost depends on the style and size of bat house, average temperatures in your area in July, and certain other physical limitations. Bat houses can be mounted on wooden posts, steel poles, pivot poles, or on the sides of buildings, but should not be mounted on trees for three reasons:

  1. They receive less sun among the branches
  2. Bat tenants are more vulnerable to predators
  3. Obstructions in the form of branches and surrounding vegetation make it more difficult for bats to drop into flight.

Also, don’t put them under the eaves of your house or on the side of it because it will encourage them to crawl under the eaves and into the house or attic.

Bats find houses mounted on poles or buildings in less than half the time it takes them to find tree-mounted roosts. Houses mounted under the eaves on wood or stone buildings (not buildings that you live in), but still exposed to the sun, tend to be better protected from rain and predators and have been especially successful. Bat houses should be mounted in an area that gets 6-8 hours of direct sunlight (facing either East or South).

Buildings offer good mounting sites almost everywhere, but they are essential in very cool or dry climates. In dry areas, where day-to-night temperatures may vary by more than 28°F, buffering from nighttime extremes is needed. Buildings are the right choice if you are installing only one, single-chamber bat house. Unless two are installed back-to-back, pole-mounted singled-chamber roosts don’t seem to offer enough options for bats to move about in response to temperature fluctuations. Pole mounted bat houses can however be very successful. Nursery colonies of up to 1,100 bats have been recorded to take up residence in pairs of nursery houses mounted on poles back-to- back, 3⁄4 inch apart and covered by a tin roof.

To the extent possible, locate all houses 20 to 30 feet from tree branches or other obstacles and 12 to 20 feet above ground (or above the tallest vegetation beneath the bat house). Those located nearest an area’s largest water source are typically the most successful, as are those in or adjacent to the most diverse or natural vegetation. The best locations are along streams, rivers, lakes or forests because these are natural bat flyways.