We must remember that although bats sometimes get in our way, we are more often in their way. Bats have lived on the Cayman Islands for 25,000 years. Humans have taken over many of their original habitats and feeding grounds. The bats are simply trying to use what is available to them now, in a very changed environment. Only insect-eating bats live in human structures. Fruit bats roost in smaller groups in caves and thick bush. If you farm, garden or don't like mosquitoes, remember that each bat in your house eats over 2,000 insects, including garden pests every night!

The mere presence of bats is not a problem. Bats are not related to mice and rats. They will not invade the living quarters, chew wood or wires or damage the building in any way. They eat only insects and will not get into stored food. Bats are not vermin! They pose no health problem for humans or pets. If bats are over a patio or garage or in the eaves over the garden, don't worry! Some people simply spread a plastic sheet under the bats and collect the guano (bat droppings) to use as a fertilizer. (Use it carefully; it is very strong!)

In houses with Spanish tile roofs, bats are usually not in the attic space but under the tiles. In this case, bats can be allowed to stay. No harm will come to the house or the people living in it from these bats. The droppings are simply blown away in the wind.

Bat guano build-up inside roof spaces is the main reason to remove bats from your building. If bats are living in your roof and you want them to leave, there is a well-researched and effective way to remove them. Do not plug bats' main exit holes without first getting the bats out. If you have a bat problem, call the National Trust at 949-0121 and ask for our free information. We can recommend a reputable company to help you, or give advice for a "Do It Yourself" bat exclusion.

Bats leave their roost almost every night to feed. To exclude the bats from the roof space, first get some helpers and watch all sides of your house at sunset when the bats leave. They usually emerge from only one or two holes, and these are the main points of entry and exit. (Any hole with bats seen coming out is a main exit hole.) Often, however, there are other holes that they can use. Stop up all the minor holes you see. Then, arrange a "one-way valve" at the main holes.

A new method that is working well uses a one-foot length of 2" PVC pipe as a one-way tunnel. Bats slide out, but can't land on the end of the pipe to climb back in. Secure the pipe over the hole and seal all the edges. If bats are entering through a missing vent in a soffet, the National Trust can lend you a pipe and plywood device that will work to exclude bats if you seal all other holes in your roof. Allow several days for all the bats to leave. Be sure they are not still using any other openings. If the weather is bad, it may take up to a week for them all to come out.

Another method that works well is to tape or staple a piece of window screen or netting loosely over the main exit. It should hang down two feet below the hole. Secure it at the top and sides, but leave the bottom open. The bats will come out under the screen, crawl to the bottom and fly away. When they return they will be unable to get around the screen and re-enter the building. Watch each night after you have installed your bat exclusion device to make sure it is working properly. This works best if the wall is a smooth surface. If the wall has a rough surface, bats may be able to land on it and crawl back up under the screen. If bats are stuck and can't get out, loosen the netting. It may take several adjustments to get it right. Every exclusion is a little bit different. If bats are still getting back in, modify your design.

If you do not give all the bats enough time to leave before plugging holes, dead bats will be an odour problem in your house. All the holes must be plugged permanently AFTER the bats are out. Use screen, wood, cement, caulk, spray foam in a can, or whatever is appropriate for your building. If this is not done, the bats will return. Bats don't chew new holes to get back in, but will sometimes chew their way out, rather than use an exclusion device. Then, after the new hole is there, they will use it to come back in. Bats can squeeze through very tiny cracks. Bats that roost in houses are usually Velvety Free-tailed Bats, but other more rare species sometimes find their way into our attics and roofs. Some of these rare species are found only on a few Caribbean islands, and one is found only on Grand Cayman! It is very important to protect these rare species, but our common bats also need protection.

Large bat colonies eat tons of harmful insects and are a big part of our ecosystem.

There is never a reason to poison bats. Attempts to do this are hazardous and unnecessary. Since bats will not take bait, poisons used on them must be breathed or absorbed through the skin. These types of poisons are not healthy for children, pets, old people, or anyone else! Some bat poisons are deadly to people. Burning sulphur or commercial bat repellant products (usually just mothballs!) don't work very well.

Never evict bats during June, July, August, September, October or November when baby bats would be separated from their mothers and left to die. This is unwise, as bats bear only one baby a year and an entire generation would be lost. Dead baby bats in your attic will also cause an odour problem in your house.

An important part of moving bats out of your building is to give them with another place to go. To provide housing for our valuable bats, and to keep them from moving into your neighbour's roof space, buy or build a bat house for your excluded bats. Install your bat house a few weeks before your plan to do your bat exclusion. Be a good neighbour and provide the bats with a safe, permanent home. Free plans for building your own bat houses are available from the National Trust, or completed bat houses may be purchased. Ask at the Trust for a free inspection of your property and advice about where and how to mount your bat house.

Bat Houses Are Fun, Educational, And Good for the Environment!

Cayman Islands' bats need someplace to live. They are not welcome in people's attics and roof spaces, and most of the old forests have been cut down to make way for development.
Special bat houses are being used now to give these interesting little animals a place to go. If a bat house is put up on the side of a building or on a tall post, bats that have been forced to move out of an attic may find it and move in!

Bats here always look around buildings for habitat. Bat houses are a new idea, and it may take a few years before all our bats learn how to use them, but there have already been some successful bat houses in the Cayman Islands.

Many people enjoy having a bat house in the garden. There are always colonies of bats looking for new homes. Watching and counting the bats as they fly out each night is interesting and educational. Droppings can be collected from underneath the bat house and used in the garden. Only insect-eating bats will live in bat houses. Fruit bats will not use them. Bat houses are easy and cheap to build. Instructions for building several different types of bat houses can be found, or ready-made bat houses are for sale at, the National Trust house.

People who are excluding bats from their attics should make putting up a bat house part of the job. This way the bats will not move into the neighbour's roof spaces! Bats need a safe, permanent home.

Only insect-eating bats live in human structures. If you farm, garden or don't like mosquitoes, remember that each bat in your house eats over 2,000 insects, including garden pests every night!

For more information, call the National Trust at
949-0121 or email us
- We take your bat problems very seriously and will do all we can to help.

Download a pdf copy of the Bat House Designs to print on your computer. (132K)

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