Brazil: Ilha Grande designated as bat conservation area
Researchers from Rio de Janeiro State University use nearly invisible mist nets and sound recordings to monitor bats on Ilha Grande, in Angra dos Reis, on the state’s southern coast. Their work, which has already led to the discovery of a new species, recently earned the island international recognition as an Area of Importance for Bat Conservation (AICOM).
Granted by the Latin American and Caribbean Network for Bat Conservation (Relcom), the certification serves as a tool to protect both endangered and non-endangered bat species by recognizing protected areas.
Relcom recognizes areas that meet at least one of the following criteria: host species of national or regional conservation concern; contain refuges used by one or more such species; or have high species richness, regardless of threat level.
Ilha Grande is one of the most bat-diverse areas in the state of Rio de Janeiro, with 37 documented species. This s for 19.9 percent of all known bat species in Brazil, 37.8 percent of those in the Atlantic Forest, and 46.8 percent of the species recorded in the state.
“Bats are little-known animals. People often fear them and are unaware of their vital role in the environment. This international recognition for Ilha Grande is important because it will help raise awareness and understanding of bats,” says Luciana Costa, a researcher at the Mammal Ecology Laboratory at the State University of Rio de Janeiro.
“Bats are crucial to us because of their diverse feeding habits. They disperse seeds, pollinate plants, and control insect populations—yet few people realize this,” says Costa. “If bats were to go extinct, the consequences for the world would be devastating,” she adds.
Getting to know bats
Bats are mammals with thin membranes stretched between their fingers, forming wings. In addition to flying, they navigate and hunt using sound. They emit sound waves that bounce off objects and return as echoes, allowing them to map their surroundings and locate prey or food.
These animals, which have inspired fictional figures like vampires and the superhero Batman, are most active—and noticeable—at night. They exhibit a wide range of feeding habits.
Costa explains that some bats feed on fruit, unintentionally aiding in seed dispersal, reforestation, and the pollination of flowers—especially those that bloom at night. Others consume insects, helping control agricultural pests and disease-carrying mosquitoes. Some species even prey on small vertebrates, such as lizards and rodents.
Hematophagous bats—the blood-feeding species—are the most feared. “These are the bats people are most afraid of. They do exist, but it’s important to that they were here long before humans,” the researcher explains. “They feed on large mammals such as tapirs and armadillos, and on large birds.”
Research on Ilha Grande
According to Costa, all these types of bats can be found on Ilha Grande. In the region, research conducted by the Mammal Ecology Laboratory relies primarily on two methods. One involves using mist nets to capture the animals, which are checked every 20 minutes to prevent bats from remaining trapped for too long. After identification, the bats are promptly released.
The other method is acoustic monitoring. “We record the bats’ echolocation calls and analyze them in the lab to identify the species,” Costa explains. She notes that this technique led to the first recorded sighting of Promops centralis in Rio de Janeiro. Although the species was already known in Brazil, it had not previously been documented in the state.
“It’s an insectivorous bat that flies at high altitudes, which is why it doesn’t get caught in mist nets. Through acoustic monitoring, we were able to detect the species and officially extend its known range to the state of Rio de Janeiro, where it hadn’t been documented before,” she says.
Ilha Grande is also home to several notable bat species, including Furipterus horrens, classified as vulnerable on Brazil’s endangered species list; Lonchophylla peracchii, native to the Atlantic Rainforest; and Myotis nigricans and Myotis izecksohni, both endemic to the biome. The island also hosts Tonatia bidens, listed as “data deficient” by the International Union for Conservation of Nature, meaning there is insufficient information to determine its risk of extinction.
Living with people
Due to deforestation and the expansion of urban areas, bats are coming into closer with humans. In addition to sheltering in tree hollows and beneath leaves, they are now increasingly found in rooftops and buildings across the island.
Sometimes, buildings can even benefit these animals. “When a house is built with a roof that has gaps, bats may see it as an ideal shelter—protected from rain and predators. It creates a safer environment where they can reproduce more easily,” the researcher explains.
This growing proximity also highlights the need for greater public awareness. The “Bats in the Square” project, developed by the Laboratory in partnership with the Federal Rural University of Rio de Janeiro, seeks to promote environmental education among the island’s residents.
Residents are advised not to touch bats to avoid bites and to be cautious around areas where bat droppings accumulate. Inhaling fungal spores from the droppings can cause diseases like histoplasmosis, a lung infection that can spread throughout the body. In such cases, the recommendation is to wear masks and protective gear, and to moisten the droppings to reduce the spread of spores in the air.
Another key guideline, according to Costa, is to avoid killing bats. “They are wild animals protected by law, so killing a bat is a crime,” she emphasizes.
