What makes one bat take risks and venture far from its roost in search of food, while another stays close to familiar, safer areas?

A new study from the School of Zoology at Tel Aviv University (TAU) reveals that the environment in which a bat is raised during the first months of its life largely determines how it will behave in the wild, sometimes even more than its innate personality.

The study, led by doctoral student Adi Rachum from the laboratory of Professor Yossi Yovel at the George S. Wise Faculty of Life Sciences and Sagol School of Neuroscience, was published on November 11, 2025, in the journal eLife.

The research investigated for the first time how early exposure to a variable and challenging environment affects the behavior of Egyptian fruit bats after they are released into the wild. The researchers raised 40 young bats in two completely different environments: one enriched and dynamic, in which the bats had to cope with new challenges every day in order to obtain food; and the other stable and unchanging. After a period of several months, their behavior in the wild was monitored using GPS devices that tracked their every flight.

The findings were clear and consistent: bats raised in the enriched environment exhibited much bolder and more exploratory behavior in the wild. They flew farther away from “home,” spent more time out foraging at night, and explored areas almost twice as large as those explored by the control group.

For example, bats raised in the enriched environment explored average foraging areas of approximately eight square kilometers, compared to only about three square kilometers among bats raised in the impoverished environment. The maximum distance they ventured from the colony was also notably greater, an average of about 1.3 kilometers versus only 0.8 kilometers in the comparison group. In addition, they spent an average of roughly four hours outside the colony each night, compared with less than three hours among bats in the control group.

To ensure that the differences did not stem from variations in the bats’ innate personalities, the researchers assessed the young bats’ personality traits in the laboratory before they were exposed to the different environments. They found that these traits did not predict the bats’ behavior in the wild as adults. In other words, the bats’ innate disposition did not account for their later differences in behavior in the wild. Instead, the environment in which they were raised during their early life proved to be the decisive factor shaping how they behaved as adults.

“Fruit bats are animals with remarkable behavioral flexibility and learning capacity,” Rachum says. “We found that the early environment to which bats are exposed influences the way they explore the world.”

“In previous studies, we identified behavioral differences between exploratory urban bats and more ‘conservative’ rural bats,” Professor Yovel adds. “The current findings may explain how these differences between the groups are formed.”