With the changing seasons, migratory bats are swarming the night skies over campus. But they will no longer be sleeping days above the bleachers at Toomey Field. A bat hotel inside the walls and under the floor of the Toomey Field press box was shut down last month after a bat tested positive for rabies and a student underwent a series of rabies inoculations. Meanwhile, the campus is stepping up efforts to control rats that have been reported recently in older buildings along the arboretum. Environmental Health and Safety Director Julie McNeal said roof rats have been thriving on a variety of food sources-bread crumbs scattered for the ducks, livestock feed in animal pens, garbage tossed in uncovered trash cans and even snacks left in people's offices. "The message to the campus is don't leave food out. Don't feed the ducks. Don't feed critters, or you'll just end up feeding the rats," McNeal said. Environmental Health and Safety, grounds and contract employees have been setting out traps to catch rats in areas reporting problems, she said. In the meantime, McNeal and other campus officials are working to develop a program of more systematic rat control. "We should be controlling the population so we don't have the problems," McNeal said. Campus environmental planners and wildlife experts, on the other hand, are generally trying to foster bats, which eat insects. However, the discovery of the rabid bat on Toomey Field required one colony to find another place to roost. The student had picked up the sick bat, put it in a cup and took it to the veterinary teaching hospital after finding it under the bleachers in early September, said Yolo County environmental health aide John Beereboom. While the student wasn't bitten, she received the six-shot treatment as a precaution, Beereboom said. Rabies is fatal if not treated soon after exposure and can sometimes be transmitted by the saliva of an infected animal. To encourage the bat colony to move elsewhere, campus employees covered openings in the press box walls with plastic sheeting that allowed bats to leave but made it difficult for them to get back inside. About three weeks later, after all the bats were out, workers used insulation and caulking to seal the walls, said Dan Kermoyan, safety adviser with the campus Environmental Health and Safety Office. The work was finished before the Aggie's second home game against Humboldt State University on Oct. 2. Spaces between the corrugated metal siding and wooden walls had previously enabled the bats to crawl up into a floor space between the press box's two levels, Kermoyan said. No bats were killed in evicting the colony, said campus veterinarian Phil Tillman. Tillman said the Mexican free-tailed bats bear their young during the summer, so the babies were weaned and able to fly by the time the stadium press box was bat-proofed. Unlike the killer creatures portrayed in the horror movie, Bats, which opened two weeks ago, the flying mammals are "immensely beneficial" to humans, Tillman said. Many bat species eat insects that damage crops and spread disease. However, human fear of bats has led to their rapid decline. Many species are endangered. Only 1 percent to 2 percent of the Toomey Field bats likely had rabies, Tillman said, given the statistics for other bat populations. "It was just kind of an undesirable proximity of the bat colony and people," he said. "Remember they're active at dusk. Picture the homecoming game." He urged people to avoid contact with any bat that's behaving abnormally, and to instead report it to Environmental Health and Safety at 752-1493. "If you see a bat that looks sick or you see it out and about in the day, do not touch it and do not go anywhere near it," Tillman said. Mexican free-tailed bats, which have short mouse-like tails, typically migrate through Davis in the fall on their way to wintering grounds in Mexico. However, some stay here for the winter. Tillman knows of one colony that lives under an arboretum bridge. Evidence showed that the Toomey Field colony had lived there for a number of years, said Beereboom of Yolo County Environmental Health Services. The animals are so unobtrusive that their roosting place might have gone unnoticed if it hadn't been for the discovery of the rabid bat, he said. Sports reporters covering Aggie games never noticed they were sharing the press box with bats, said Mark Honbo of the campus Sports Information Office. Beereboom said two bats have tested positive for rabies in Yolo County this year-the one on campus and another in Woodland. Last year, the county had four confirmed cases of rabid bats-two found in El Macero and the other two removed from campus buildings, King Hall and the physics building. Beereboom said the campus does a good job alerting people to the risks of rabid bats. "They start waving red flags." For more information about bats and rabies, see the Sacramento County Public Health Department's Web page.