Just check out the photo above, snapped by biologist Cal Butchkoski of the Pennsylvania Game Commission, of a bat box in Pennsylvania chock full of bats!!
Putting up a bat roosting box can help replace lost or degraded habitat that has been contributing to the decline of bat populations throughout North America. Bats in Maryland that are likely to inhabit bat boxes include Little Brown Bats, Big Brown Bats, Northern Long-eared Bats, and Evening Bats.
You can increase your chances of successful occupation by keeping in mind the following criteria recommended by Bat Conservation International’s Bat House Research Program:
Outside dimensions of houses should be about 2 feet tall and at least 14 inches wide with a 3-6 inch landing area.
Roost partitions should be ¾” to 1”.
Ventilation slots should be ½” wide.
Half inch plywood is best for fronts, backs and roofs, and roosting partitions.
1” board lumber is best for sides.
Prior to painting all seams should be caulked with latex caulk that remains flexible over time.
Paint exterior surfaces with two coats of exterior latex paint (dark brown, dark gray or dark green is best for Maryland).
Boxes should receive at least 6-7 hours of direct sun
In Maryland, boxes should be oriented southeast or southwest.
Box should be within ¼ mile of water (stream, river or lake) with a mixture of different habitats (forest, agriculture)
Locate 20-25 feet from the nearest trees
Boxes should be mounted on poles or buildings at least 10 feet off the ground, preferably 12-15 feet, or more.
Open-bottom designs are less likely to be occupied by birds, mice, or squirrels.
Paper wasps may build nests in partitions > ¾”. Mud daubers are seldom aggressive and have weak stings.
Nests of both species can be knocked down in spring with a high pressure water hose.
Have you seen bats at your house or in your neighborhood? Bats are commonly misunderstood but extremely important animals in Maryland. Unfortunately, bats in Maryland and in much of the United States are in decline. We would love to know more about Maryland's local bat roosts to assist with their conservation! To help out, please fill out our Bat Roost Reporting form.
For information on creating bat houses, check out our Bat Box web page.
Photo of Bat House by SFAJane Flickr CC by 2.0
580 Taylor Ave., Annapolis MD 21401
Call toll-free in *Maryland* at 1-877-620-8DNR (8367)
Out of State: 410-260-8DNR (8367)