You may be surprised to learn that bats can be found living in urban areas around the world.
04.16.25
By Alyson Brokaw
Time it just right and you might make it for rush hour on Congress Ave Bridge in Austin, Texas. But don’t worry – no delays are expected unless you’re a Mexican free-tailed bat (Tadarida brasiliensis) trying to join the steady stream of up to two million bats leaving the roost at sunset each night. These bats have been living the city life since 1982, showing that urban areas can be places where some wildlife can thrive. Austin isn’t the only city where bats can be found, and you may be surprised to learn that bats can be found living under bridges, roosting in culverts or tucked into eaves and attics in urban areas around the world.
City Bats
Urbanization, the process of transforming natural habitat into landscapes of concrete, roads, houses, and skyscrapers, is considered a significant threat to biodiversity worldwide. For some species, urban and suburban areas remain tolerable and may even offer unique opportunities. Smaller, insectivorous bat species tend to be more successful in urban areas, where food availability may be more limited. Bats with long narrow wings, adapted to flying fast in open space may also be more common in cities – their long narrow wings make them efficient commuters between the city and their nightly hunting grounds.
Blame this one on Batman if you must. It’s true that many species of bats flock to caves to sleep or hibernate thanks to their steady temperatures and humidity levels – such as the famous Mexican free-tailed bats (Tadarida brasiliensis) in Bracken Cave, Texas. However, bats can commonly be found roosting in many locations that provide shelter from the elements and predators, including including under tree bark, in hollow tree trunks, between tree leaves, hanging in the rafters of barns or sheds, under bridges, in rock crevices, or even nestled in curled up tropical plant leaves.
City living can offer bats some important creature comforts. Roosting habitat in the form of bridges, roof crevices, and other human-made structures can act as replacements of habitat lost from development. Cities may also create new habitat for certain species in areas where roosting habitat was once rare, such as near prairies. Highly developed areas may also be warmer than surrounding habitat, thanks to all that heat-trapping asphalt and concrete, which may be beneficial for some species. Increased availability of human-made water sources, like retaining ponds, fountains, and swimming pools also provide vital drinking water for thirsty bats.
Challenges of the City Life
Bats living in urban and suburban areas face some unique, if familiar, challenges. Bats that roost in human-made structures such as bridges or buildings, usually still need to travel to reach insect-rich hunting grounds. Depending on the layout of the city, this can mean traveling farther than they would otherwise, and having to dodge hazards like roads and highways.
Between the rumble of the highway, hums of electrical boxes and seemingly unending construction noises, urban areas can be loud. While some bats may be relatively tolerant of loud noises while roosting during the day, competing with background noise while trying to hunt using echolocation presents a challenge. Bats may try to adjust their calls to be louder against background noise, and anthropogenic noise may have a bigger impact on bats that use lower-frequency calls. Noise can also impact bat hunting success, either by masking the sounds bats need to hear prey or by acting as distractions.
Unlike bats, humans are daytime creatures, meaning we need the help of artificial light to navigate at night. While some bats take advantage of artificial lights (and the insects they attract) for hunting, many other bats are negatively impacted by lights. Some bats, like the lesser horseshoe bat (Rhinolophus hipposideros) will go out of their way to avoid lighted areas, resulting in longer commutes and increased energy use each night. Even bats that are frequently found living in urban areas, like the common pipistrelle (Pipistrellus pipistrellus) will avoid crossing brightly lit areas, which reduces their connectivity and ability to move through a city.
Bats with Benefits
Bats play important roles in the ecosystem, whether that ecosystem is a pristine forest or our suburban backyards.
Free-tailed bats like those in Texas cities are major predators for crop pests and their crop-saving services are worth an estimated 700,000 dollars a year in the south-central Texas region alone. Similarly, bats living in urban areas of Brazil were estimated to save nearby farmers as much as 390 million dollars per year in pest-control services.
Urban bats can also help out in some unexpected ways. The Biblioteca Joanina at the University of Coimbra in Portugal is home to more than 60,000 books, including historic texts and rare first editions. Old books are a favorite snack for certain beetles and moths, making protecting these books a challenge. Luckily, the resident colonies of soprano pipistrelles (Pipistrellus pygmaeus) and European free-tailed bats (Tadarida teniotis) are up to the task, protecting the books and acting as free pest control since at least the late 18th century.
Playing Nice with Batty Neighbors
Even in the heart of a bustling city, access to green spaces, like parks, ponds or small areas of nature are fundamental for the well-being and health of humans. Likewise, green spaces can be beneficial for city bats.
Areas with native habitat can provide roosting and foraging spots for bats, while tree-lined walkways and rivers can act as corridors for bats that prefer to hunt outside of the city.
Tree cover may also dampen the negative effects of street lighting for some European bats like noctules (Nyactalus spp.).
In places like New York City, available green space on the ground may be limited, but rooftops can act as alternatives. Green roofs, or rooftops with vegetation and gardens instead of just more concrete, can be an important tool in maintaining and promoting biodiversity in urban environments. In addition to supporting pollinators and foraging birds, green roofs may also provide hunting habitat for a range of bat species, including big brown bats (Eptesicus fuscus), silver-haired bats (Lasionycteris noctivagans) and red bats (Lasiurus borealis).
In circumstances where bats need to be excluded from an existing roost (due to construction or safety concerns), alternative roosting habitat in the form of bat houses can be a way to support urban and suburban bats. In Miami, Florida, specialized designed bat houses have been installed throughout the city to provide much needed habitat for the rare and endangered Florida bonneted bat (Eumops floridanus). These efforts highlight how human intervention can help mitigate habitat loss, even in highly modified landscapes.
It’s important to underline that while some bat species and populations may seem to benefit from urban environments, it is still far outweighed by the negative impacts on other bat species and wildlife, often unable to adapt to the city life and threatened with extinction when their native habitats paved over. But for those bats we humans share space with, we can be good neighbors. By understanding how bats navigate urban environments and the challenges they face, we can find ways to support them and ensure they continue to thrive.
Alyson Brokaw, PhD is a behavioral ecologist, sensory biologist and science communicator. When not talking about bats, she can be found cuddling with her dog, exploring her local Pennsylvania woods and throwing plastic on the ultimate frisbee field.
