Bats are an important part of the ecosystem. In the eastern U.S., all of our bats are insectivorous which means that they eat insects. Many of the insects they eat are ones that we would consider pests. Unfortunately, populations of many of our bat species are declining for a variety of reasons.
One of the ways that some people try to help is by putting up a bat box or bat house. Attracting bats to their yard or neighborhood also allows them to take advantage of the free pest control bats offer. If you’re thinking about buying and putting up a bat box, here are five things you should consider before doing so.
1) What type of bat box should you get?
You can find several different styles of bat boxes for sale and/or plans to build your own, but not all of these may be safe for bats. Some bat boxes may get too hot during the day or cool off too quickly at night. Research into this topic is still ongoing. (Listen to the Backyard Ecology podcast episode, Bat Boxes and Bat Houses, to hear about some of this research.) Bat Conservation International recommends either rocket box style bat boxes or 4-chambered traditional style boxes.
Rocket box style bat boxes are built so that the bats can roost on any of the four sides of the boxes. This allows them to find cooler or warmer spots, as needed, by moving to the sunnier or shadier side of the box. They are called rocket boxes because they can look kind of like a rectangular bottle rocket or model rocket.
The traditional style boxes are the flatter style boxes that you more commonly see plans for and find around people’s homes. In the past, these bat boxes were often built with only a single chamber, or one big room, on the inside. However, newer research shows that having at least 4 chambers, or rooms, gives the bats more options for moving to warmer or cooler spots. Think about it like being able to add or kick off the covers at night.
Regardless of style, bat boxes should be at least 2 feet tall and 16 inches wide. Larger is ok, but smaller boxes tend to get too hot or too cold.
2) What color should it be?
Traditionally, the recommendation was to paint your bat boxes a dark color so they would soak up more sun and thus be warmer. However, in many parts of the country, dark bat boxes located in full sun can get too hot, and even cause bats to overheat and die.
Newer color recommendations vary based on where you are located. Below are the colors that Bat Conservation International recommends painting bat boxes based on a location’s average high temperature in July.
- Less than 85: black
- 85 – 95: dark or medium color
- 95 – 100: medium or light color
- Over 100: light color or white
Some people will install multiple bat boxes of different shades with darker bat boxes in shadier locations and lighter bat boxes in sunnier locations. This gives the bats options. However the pups, or baby bats, still can’t move freely between boxes because they can’t fly. The pups can only move between boxes if they hitch a ride on momma.
3) Where should you put your bat box?
Rocket boxes can only be mounted on a pole that goes up the center of the box. The traditional style bat boxes can be mounted either on a pole or on the side of a building. Research by Bat Conservation International showed that bats preferred traditional style bat boxes mounted to wood, brick, or stone sided buildings over the same style mounted on a pole, but rarely used traditional style bat boxes mounted to metal buildings. Bat boxes should never be mounted to a tree because they tend to have higher predation rates than bat boxes mounted on a pole or on a building.
Regardless of where you mount your bat box, it should be in a fairly sunny area. It doesn’t necessarily have to be full sun, but more sun than shade is usually recommended.
4) How high up should it be?
The bottom should be a minimum of 10 feet above the ground and any vegetation. Higher is better – 20 feet is excellent, but may be difficult to attain in a home setting. The reason that you want your box so high is because the bats will literally drop out of the box and then start flying from a freefall position. They have to have enough space between the box and the ground / vegetation in order to pull out of the freefall before they hit the ground.
5) How many should you put up?
Bat Conservation International’s research showed that bats tended to use bat boxes more often when there were three or more available in one location. Multiple bat boxes can be mounted side by side on a building, on multiple poles installed next to each other, or back-to-back on a pole if you have two traditional style boxes.
However, don’t feel like you have to put up multiple bat boxes. Only putting up one is ok too. In other words, put up the number of boxes that is right for you.
Attracting bats to your property and neighborhood by installing bat boxes can be a great way to help bats and get some free, all organic, natural pest control. As you choose your bat box and its location, it is important to keep the latest scientific research and recommendations in mind. That way your bats are as healthy and safe as they can be in the homes you provide them. Bat Conservation International is a good place to go for the latest information about bat boxes and plans to build them.
Unfortunately, putting up a bat box isn’t a Field of Dreams scenario. Just because you build it or install it, doesn’t mean the bats will come. Sometimes, for whatever reason, bats never seem to use a bat box. In those cases, it may be helpful to try to find a local expert who can advise you. However, bats are such interesting and helpful animals to have around that it is definitely worth trying to attract them and a bat box (or two or three) can be a good start.
Backyard Ecology: Exploring Nature in Your Backyard
Nature isn’t just “out there.” It’s all around us, including right outside our doors. Hi, my name is Shannon Trimboli, and I am the host of Backyard Ecology. I live in southcentral Kentucky and am a wildlife biologist, educator, author, beekeeper, and owner of a nursery specializing in plants for pollinators and wildlife conservation. I invite you to join me as we ignite our curiosity and natural wonder, explore our yards and communities, and improve our local pollinator and wildlife habitat. Learn more or subscribe to my email list at www.backyardecology.net.