Cities have become an important haven for bats. Of the 178 species of this group of mammals found in Brazil, 84—nearly half—live in urban centers, mainly in parks or forest fragments, according to a study by the Federal University of Paraíba (UFPB) published in the journal Urban Ecosystems in December 2016. The study, prepared from an analysis of 111 scientific papers, reports on bat occurrences in 65 Brazilian cities.
In the South and Southeast, the most common species is Artibeus lituratus, a frugivore with a white-striped head that lives alone or in small colonies in treetops, cellars, air conditioner housings, garages and roofs. In addition to the frugivores, there are species that eat insects and others that feed on flower nectar. Hematophagous bats, which are very rarely found in cities, feed on blood from cattle, horses and birds and, although there are just three such species in the world, they are principally responsible for the negative image attributed to these animals.
The UFPB researchers were surprised to find such a great diversity of species in urban areas, but they were also concerned. “We need to assess the health of the bats that live in cities, because we’ve already seen that an urban environment can be detrimental to other wild mammals, causing them to have fewer offspring and to eat much more, owing to the presence of garbage, than they do in forests,” says biologist Pedro Estrela, a professor at UFPB and head of the group that conducted the survey. “In the Paraíba State capital, João Pessoa, we captured bats with wounds or suffering from alopecia (lack of hair), which are possible signs of stress,” observes biologist and team member Hannah Nunes.
The surveys in Paraíba’s capital city give an indication of how to defeat the greatest enemies of these animals: prejudice and lack of information. Although bats are generally harmless, they often inspire fear and repugnance among humans. Despite being protected by law because they are wild animals, they are harassed and usually driven away or killed by residents who are disconcerted when the creatures invade their living rooms, bathrooms or garages. These unique flying mammals can easily startle onlookers when they leave their roosts—crevices in buildings, tree trunks, ceilings of houses—en masse at dusk. They are seldom valued for their ecological role, which is beneficial to people because they are voracious consumers of insects. In addition, they pollinate flowers and disperse seeds, thus facilitating plant proliferation.
“Displaying the animals helps a great deal in overcoming prejudice,” Nunes suggests. In 2014 and 2015, she went out looking for bats in the urban environs of João Pessoa and captured 3,427 of them from 23 species, mainly in forest fragments. She notes that the residents who went along on the hunts were surprised to see the bats up close and to realize that their fur is similar to that of dogs.
In Greater São Paulo, 43 species have now been identified. The most common ones belong to the genus Artibeus, found mainly in parks, according to the surveys by the Center for Zoonoses Control (CCZ) in the state capital, conducted jointly with other institutions. Adriana Ruckert, a biologist at the CCZ, has observed the bats’ adaptation to urban environments. She has even found them in noisy places, like garment shops and other factories, despite the fact that they have sensitive hearing. “They are afraid of light, yet they take advantage of streetlights to hunt for insects,” she says.
The CCZ team receives an average of three requests for help each day from people who are desperate when a bat unexpectedly flies in through the window, hides in a bath towel or slips behind the kitchen cabinets. According to the CCZ team, there is a tremendous lack of information. “We once were sent a swallow that a resident thought was a bat,” says Rucker. “Once a woman called to report a huge bat that had black wings and a beak, sitting in the window. It was a vulture….”
Ignorance has led to situations of both extreme cruelty and great compassion. More than once, Ruckert’s team has been given headless bats because some people believe they must be decapitated due to the negative connotations they convey—for example, their identification with mythical figures in literature, such as vampires. The opposite often happens. A woman called to ask about how to care for a bat that she was unsuccessfully trying to feed milk. In Cotia, in Greater São Paulo, an insect-eating Myotis nigricans was found after falling into the back yard of a house, and a group of children wanted to take care of it; the CCZ team asked them to hand over the animal and recommended that the children immediately begin taking serum and get vaccinated for rabies, which was subsequently identified in the bat. “When bats allow themselves to be caught, it means that they may have rabies,” she says.
Towards a peaceful coexistence
Of the 400 bats collected on average each year in the capital and examined at the CCZ, only three or four carry the rabies virus, the most common disease-causing agent transmitted by these animals. Of the 84 species in the national study, 27 had at least one of the 11 types of disease-causing agents on record, mainly the rabies virus (75% of cases).
In addition to rabies, the CCZ investigates other diseases associated with bats. In one of its laboratories, biologist Adriana Menezes is in charge of regular testing to look for the Histoplasma capsulatum fungus in bat entrails and feces. H. capsulatum can cause serious infections in people with a weakened immune system (see Pesquisa FAPESP Issue No. 243), but healthy people can also develop problems, she says. “The seriousness of the infection varies, depending on the degree of exposure to the fungus and how much time passes before diagnosis.”
In December 2016, Menezes identified this fungus in samples of bat feces from the municipality of São Paulo, using real-time polymerase chain reaction, a technique she implemented in the lab. The following month, another sample tested positive using the same methodology. With this test, she now obtains same-day results, compared to the nearly 50 days it used to take when the fungus had to be cultured for identification. Biologists can then immediately advise residents in the collection areas to clean their ceilings (while wearing a mask) to prevent the fungus from spreading.
With her CCZ colleagues and volunteers in the Program for Bat Conservation in Brazil (PCMBrasil), Ruckert has promoted Bat Day each October 1 for the past three years, by recreating caves, tree hollows and roofs of houses. In 2016, the event drew 300 children and adults to Ibirapuera Park. She also prepared a brochure entitled Dez motivos para gostar de morcegos [Ten reasons to like bats], which points out that these animals will eat hundreds of insects in just a few minutes. For their part, biologists from the Butantan Institute have prepared the Guia para convivência com morcegos [Guide for coexisting with bats], which notes that a bat that comes in through the window of a house is almost always as frightened as the people who find it (see box). The Butantan team sponsors meetings with schools, in addition to walks through the Institute’s woods, where 11 bat species have been identified. “Observing bats is a way to connect with nature, just as you can with birds, butterflies, tamarins and other animals that live in cities,” says biologist Erika Hingst-Zaher, who heads the Butantan Bird Observatory.
Study of the prevalence of Histoplasma capsulatum and Sporothrix spp. from environmental samples in the urban area of São Paulo (No. 14/06571-2); Grant Mechanism Regular Research Grant; Principal Investigator Adriana Araujo Reis Menezes (CCZ-SP); Investment R$126,221.14.
NUNES, H. et al. Bats in urban areas of Brazil: Roosts, food resources and parasites in disturbed environments. Urban Escosystems. 2016 (In production).