Where Do Bats Live? Roosts in Caves, Trees and Buildings

What is a bat roost?

A roost is any place where bats rest during the day, shelter from bad weather or spend the winter. Bats choose roosts carefully, because the right temperature, humidity and safety from predators affect how much energy they use and how well their young survive.

Some bats roost alone, while others gather in clusters of thousands or even millions. Many species switch between several roosts in the same area over the summer, so a roost that is empty one week may be full the next.

Caves and mines

Caves are the classic bat home. They offer darkness, stable temperatures and protection from predators. Some caves hold enormous colonies. Bracken Cave near San Antonio, Texas, is often described as the largest bat colony in the world, holding an estimated 15 million or more Mexican free-tailed bats each summer.

In winter, caves and old mines become hibernation sites, called hibernacula, for many bats in cool climates. A good hibernaculum stays cold but above freezing, usually a few degrees Celsius, with high humidity so the sleeping bats do not dry out. The little brown bat of North America traditionally hibernates in caves and mines in large clusters, which also made it very vulnerable to white-nose syndrome, a fungal disease that spreads in these sites.

Trees and foliage

Before people built houses, most bats lived in trees, and many still do. Different species use:

• Tree hollows: old woodpecker holes and rot holes, especially in mature and veteran trees.
• Cracks and splits: narrow gaps left by storms or lightning.
• Loose bark: flaps of bark on dead or dying trees, used by several North American bats.
• Foliage: some bats, such as the eastern red bat in North America, hang among leaves and look like dead leaves or pine cones.

In the tropics, flying foxes roost in the open in tall trees, sometimes in camps of thousands. Small tent-making bats of Central and South America bite through leaf veins so the leaf folds into a shelter.

Buildings and bridges

Many bats have adapted to human structures. In Europe, the common pipistrelle often roosts in narrow gaps behind boards, tiles, cladding and roof felt, and other species use roof spaces, church lofts and barns. In North America, little brown bats and big brown bats frequently use attics and barns.

Bridges can also be important. The Congress Avenue Bridge in Austin, Texas, shelters roughly 1.5 million Mexican free-tailed bats in summer, the largest urban bat colony in North America. Their evening emergence has become a famous sight for visitors.

Summer roosts vs winter roosts

Maternity roosts are especially important. For little brown bat colonies, females prefer roost temperatures of about 23–34 °C (74–94 °F), which help pups grow quickly. Read more about winter behavior in Do bats hibernate?.

Bat boxes

Bat boxes are wooden or woodcrete shelters fixed to trees or walls to give bats extra roosts where natural ones are scarce. They work best when placed high, about 4–5 m (13–16 ft) above the ground, in sheltered spots with some sun, and close to good feeding areas such as hedges, woodland edges or water.

Bat boxes can take months or years to be used. They help, but they cannot fully replace large old trees, undisturbed caves or established roosts in buildings.

Why bat roosts are protected

Most bats have only one pup a year, so the loss of a single roost can wipe out years of breeding. Many species return to the same roosts for generations.

In the UK, all bats and their roosts are protected by the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017. Across the European Union, bats are strictly protected under the Habitats Directive. In practice, it is an offense to deliberately disturb bats, or to damage, destroy or block access to a roost, even if the bats are not present at the time. Building work that might affect a roost usually needs a survey and sometimes a license.

In the United States, several species, such as the Indiana bat, gray bat and northern long-eared bat, are protected under the Endangered Species Act, and many states have additional rules. Caves with important colonies are often gated to keep visitors out while letting bats fly in and out.

How to find out if bats live near you

You do not need to enter a roost to see bats. On warm evenings, watch the sky about 20–30 minutes after sunset near trees, hedges, rivers or street lights. Bat groups in Europe and North America run guided bat walks with detectors that turn ultrasonic calls into sounds people can hear.

If you think bats live in your house, leave them undisturbed and contact your national nature agency, local bat group or state wildlife agency for advice.