When promoting the benefits of city life to tourists and prospective residents, one of the things most cities highlight is their nightlife. However, there’s one aspect of nightlife that often remains unmentioned: urban bats.
Large populations of bats living amongst city dwellers are no urban myth. Cities are becoming increasingly common habitats for bats as these locations offer unique and attractive roosting opportunities. As ongoing development causes our cities to spread farther out into what was once suburban and rural areas, bats have learned to take advantage of the positive aspects of city life while learning to adapt to the challenges of living amongst a dense population of humans.
Bats Commonly Found in Urban Environments
In recent years, scientists and ecologists have increased their study of bats because of the important role these animals play economically and environmentally, as well as the challenges for survival many bat species face.
Interestingly, scientists have found that certain species of bats do better in urban environments than others. These urban bats have certain characteristics such as small-sized bodies, a relatively low frequency and long duration of echolocation calls, and the ability to be flexible in their choice of daytime roosts. Flexibility is important here as it is not uncommon for urban bats to have to switch roosts when they are disturbed by people. Each city will have different species depending on location, geography, and climate. A few of the more common kinds of urban bats include the big brown bat, the red bat, and the pipistrelle. The big brown bat is the species most widespread throughout American cities
What Is City Life Like For Bats?
In more natural environments, bats live in caves, trees, mines, and in crevices of cliffs and other rocky formations. In cities, bats find human-made roosts that mimic many of these places. Aside from park trees where bats hang from stems in the leaves, bats roost in attics, vacant buildings, churches, eaves, and crevices on the underside of bridges. For the most part, urban bats that live in trees migrate once the weather turns colder while those that roost in buildings hibernate.
Urban bats are insectivores meaning they eat insects. There is plenty for bats to eat in city parks as well as under streetlights where the light attracts a variety of light-loving bugs. Research shows that city lights have a profound effect on bats’ nocturnal rhythms, decreasing their overall activity. Yellow-white light has a greater impact than blue-white light. However, the pipistrelle is a light-tolerant species so it is best equipped to take advantage of the bugs that are attracted to lights.
It’s also believed that noise disrupts bats’ natural behavior, leading to a decrease in their overall health as background noise such as traffic interferes with their echolocation and makes it more difficult for them to find food.
The Battiest Cities in America
Austin has the incredible distinction of being the bat capital of America and is home to the largest urban bat colony in the world! There are an estimated 1.5 million urban bats living within the Congress Avenue Bridge in Austin.
Mexican free-tailed bats flocked to the newly renovated Congress Avenue Bridge after its 1980 renovation because it provided the perfect bat habitat:
- The bridge’s concrete crevices mimic a cave-like structure, which provides a haven for female bats to raise their young safely. This colony raises an estimated 750,000 pups annually.
- The crevices also maintain an ideal temperature and humidity for the bats to roost comfortably all day long.
- The bridge’s proximity to water provides plenty of food for the bats and their pups.
Austin loves its bat population for the bug-eliminating superpowers of these animals as well as the dramatic nightly show the colony puts on when all of those bats emerge at dusk to feed. Watching the bats emerge is one of Austin’s most popular tourist attractions. Anyone wishing to observe the bats can do so for free any evening from about March through October between the hours of 7:30 – 9 p.m. (depending on when the sun sets) by standing on the bridge or on the southeast corner of Congress Bridge and Lady Bird Lake.
Almost every city has a major park where different kinds of wildlife abound. In Washington, DC it’s Rock Creek Park. Though completely surrounded by city architecture, within the park’s 1,700 acres it feels like wilderness. Within this natural setting lives such a large population of bats that the city has dubbed the big brown bat the official mammal of Washington, D.C.
Washington, DC has eight species of bats that live throughout the district and which have been categorized into two groups: cave bats and tree bats. Most Washington DC bats migrate to warmer, more hospitable climates each winter.
Visitors and residents who want to observe bats can participate in a bat walk, led by biologists on Kingman and Heritage Islands by the Anacostia River.
New York City
New York State is home to nine species of bats, many of which are also residents of Central Parks’ expansive 843 acres. The park, with its meadows, woodlands, trails, and ponds, makes an ideal habitat for both cave-loving and tree-loving bats.
New York City’s cave bats are hibernators that stay in the city year-round, living off of their fat reserves. The tree-dwellers are migratory. They leave every year around October and return in March. The Central Park Conservancy has installed bat houses to encourage nesting and the big brown and little brown bats are the species that most commonly use them. Other bats often found in the park include eastern red bats, hoary bats, and silver-haired bats.
Bat walks through the park are organized by the New York City Bat Group which likes to show residents how bats have been right over their heads all this time. Those with a keen eye and an interest in finding these fascinating, helpful creatures can do so any time they take a stroll.