A silence fell over Museum Road as the sunset, with spectators huddled around the wooden fence waiting for thousands of nocturnal creatures to emerge.
The audience’s patience has paid off since the University of Florida bat houses opened in 1991. Here, visitors watch as thousands of bats fly into the sky each night, quickly breaking the calm with high-pitched squeaks and fluttering wings.
However, Matthew Worly, a frequent bat house visitor, is disappointed at the number of bats that have been visible in recent months, he said.
“Compared to before, I think there are way less bats,” Worly said. “It takes a lot of wind out of the whole thing.”
The bat houses host between 450,000 and 500,000 bats when at full capacity. But as of November 2024, UF Environmental Health and Safety found the houses’ bat population was alarmingly low, with less than 100,000 bats, according to UF EHS. Now, the bat population is slowly increasing – indicating that the colony’s numbers will soon return to normal.
“We’re getting some great traction up in the bat houses,” Brad Flies, pest management coordinator for UF EHS, said. “I think we’re trending in the right direction.”
The bats’ mating season takes place from April 15 to Aug. 15. This period may yield significant growth in the bat population, Flies said.
“This time of year is always important,” he said. “If they come back here to have their pups, we’ll be in good shape.”
According to Shelly Johnson, a state specialized agent in natural resources for UF’s Institute of Food and Agricultural Sciences, the mating season is when bats often return to their roosts, getting the colony much closer to its usual size.
“By mid-summer, we basically doubled whatever number was in there before that, because you have a mom with a pup,” she said. “Then by the end of the summer all those pups start flying, so then that's when the emergence is the most spectacular.”
UF EHS employees were surprised by the bats’ disappearance in the fall because of the animals' loyalty to their home, Flies said.
“They’ve never been gone like this before,” he said.
The reason for the bats' disappearance is hard to pinpoint, but hurricanes Helene and Milton and other natural factors may have impacted the houses’ residences, Flies said.
“During the hurricanes the bats would have came out at sundown, and probably could have got caught up in those winds and really just blown off track,” he said. “Or if a raccoon had maybe got up inside the actual bat house, I guess it could spook them enough that they would leave.”
According to Johnson, the two most common species that reside in the bat houses are the Brazilian free-tailed bat and the evening bat. The two commonly scatter throughout Florida during the winter, indicating that the population decrease isn’t a cause for concern, Johnson said.
“The middle of the winter is always the lowest population,” she said. “So, you can’t say that they’re missing.”
The bats could have remained in the bat houses and entered a state of torpor, a shorter version of hibernation, to endure the cold. This would result in fewer bats flying out each night, Johnson said.
“They don't come out, and they don't move around,” she said.
Discrepancies in the number of bats counted may have made the disappearance seem worse than it appeared to be.
Merlin Tuttle, ecologist and conservationist who founded Merlin Tuttle's Bat Conservation, said there is not a reliable way to count the exact number of bats, often resulting in researchers tallying drastically different population totals for colonies.
“Unless you know that the same person is counting under the same conditions at the same angle and time, you can get a very big variance in counts,” Tuttle said. “Not even a computer would be totally accurate.”
The concern for the bats' disappearance was sparked due to their importance to the ecosystem. Ralph Simon, biologist and permanent staff scientist at Nuremberg Zoo, said that bats’ impact goes largely unnoticed, but they play a vital role in important natural functions.
“They do a lot of ecosystem services,” he said. “If you didn’t have bats, we would need a lot more pesticides, which costs a lot and is actually not so healthy.”
UF EHS is confident the creature's intelligence and strong loyalty to their roost would likely lead them back to the bat houses, Flies said.
“They can go right in that colony and find their babies,” he said. “They’re really smart creatures.”
With the colony’s numbers on the rise, Worly said he is excited to see the bats “get back to full strength” in the coming months.
“I really hope the mating season brings them back,” he said. “Seeing them rush out is relaxing in an odd natural way. I want to get that feeling back soon.”