Why do bats hang upside down?
Bats hang upside down so they can fall into flight. Their wings aren’t strong enough to lift the weight of their bodies without great difficulty, so they simply turn loose from the surface they’re clinging to and spread their wings. Once in the air, they’re fast and agile fliers. If you placed a bat on a flat surface, it would walk to the nearest vertical surface and climb it to gain some height so that it could fall into flight. Placed on a surface with no adjacent vertical areas, it would walk off the edge to fly.
Do bats use bat houses?
Habitat loss is costing bats their natural roosting places at an increasing rate. So, providing bat houses for them is a great idea. However, size, placement, and habitat are important if you’re to succeed in attracting them. The success rate is only about 25 percent for smaller houses and not much greater for larger ones. Bat houses mounted in the spring, before birthing time, are more successful.
Bats seem to prefer a house that’s at least 14–18 inches (36–46 cm) wide by 2–3 feet (0.6–0.9 m) tall, placed 15–20 feet (4.6–6.1 m) above the ground. Place it near water and at least 20–30 feet (6.1–9.1 m) from the nearest tree. Hang it on the south or east side of a house, shed, or barn, so predators won’t be able to reach it. You can try hanging it on a pole or tree, but that isn’t as successful. Bats like warmth, so the house needs six hours of direct sunlight daily. Make sure it’s ventilated. The bigger the bat house, the bigger the colony it can support. Even if you do everything right, it may take a year or two before bats begin using it.
Some species that use bat houses are the Big Brown Bat, Eptesicus fuscus, the Little Brown Bat Myotis lucifugus, and the Southeastern Bat, Myotis austroriparius.
Bats in the attic
Late fall is the best time to evict bats. Never evict them during their maternity season, roughly April 15th through August 31st. Their babies can’t fly and will die if inadvertently left behind. Also, avoid evicting bats in winter, as you’ll be forcing them out during their hibernation period into temperatures they can’t tolerate, with no ready roost or food source (insects). If you’re concerned about your safety until the bats can be evicted, rest easy—they aren’t aggressive and will leave you alone. It’s only a little wait on your part, and it will save their lives.
Here’s how to evict them, according to the Organization for Bat Conservation: Enlist the help of several friends to watch different sides of your house from dusk until one hour after sunset. The goal is to find the opening(s) the bats use. Bats can get in through a hole the size of a thumb, so look closely and expect them to fly out fast. You may have to do this several nights until you find their opening. Once located, mount a bat house near the opening, and the bats will become accustomed to it as they come and go.
A week later, during the day, tape a large mesh screen on three sides around the opening(s) into your attic. The screen should extend a foot past the opening on all sides. Keep it loose enough for the bats to crawl out through the open bottom. However, they won’t be able to get back inside and will look for the closest good place to roost. Hopefully, it will be the bat house you’ve conveniently placed nearby. Just like that, you’ve evicted your unwelcome tenants but provided them with a new place to roost. Leave the screen in place for another week and then permanently secure it.
If you live more than half a mile from open water, you’ll likely never have a bat problem. Bats like forest and water edges, probably because these habitats provide large quantities of insects.
Bats and rabies
A word about rabies: Only half a percent (0.5%) of bats are found to be rabid, and in all of American history, only four cases of human rabies are known to have been caused by house-dwelling bats. None of those four were caused by the bat species most likely to use your attic.
A bat in the house
Bats aren’t aggressive, and even rabid ones won’t attack. A bat may zoom all around the room, even very close to you, but it won’t harm you. They aren’t blind, even in the daytime; they can see you very well. It’s frightened and looking for an exit. Your every instinct may be to wave your arms and try to bat (pun intended) it away, but it isn’t necessary. Take a moment to enjoy seeing one up close. As soon as it locates an open window, it’ll be gone.
Help it find an exit: Close doors to the room to keep it confined. Open all the windows (remove screens, of course). Hopefully, it’ll fly right out. If it doesn’t, you can try to catch it. When it lands on a curtain, piece of furniture, or wall, place a towel over it and scoop it up. Or, place a jar over it and a stiff piece of paper under it to trap the bat inside. Outside, open the towel or lay the jar on its side to release the bat. Be sure to release it from an elevated position.
I found an injured bat; what should I do?
The incidence of rabies in bats is very low. Nevertheless, please don’t touch it with bare hands. It needs to be observed for a time before picking it up unless it obviously cannot fly because of injuries. In that case, wear thick gloves or a thick towel to pick it up. Don’t squeeze; they’re very fragile. Bat World Sanctuary has an excellent page with precise instructions for what to do. Ultimately, you’ll need to get the bat to a licensed wildlife rehabilitator, who’ll know how to provide care. Bat World’s rescue page
Do bats form flocks?
To find out, we turned to the best source for the answer—Bat World Sanctuary. Founder and bat expert Amanda Loller says bats don’t form flocks in the sense of masses of them traveling together. They fly from their roosting place and disperse. They may stay in the same vicinity of each other, however. Within the dispersed group will be cliques of bats who stay closer to each other. The cliques also roost together within the bat colony.
Do bats accept bat “strangers” into their colony?
Bats may or may not. There are many factors at play. Some bats, such as the Big Brown Bat, are very aggressive toward unknown bats, while other species are more tolerant. Or, an otherwise tolerant colony might not accept a bat of a particular species. Bats are social animals, and a rejected one would keep looking around for a colony that would accept it.
In your yard: The Big Brown Bat, a gardener’s friend