Clear Creek school officials are sounding the all-clear signal on bats.

Elaina Polsen, a spokeswoman for the Clear Creek Independent School District, said no bats have been spotted inside any schools since Monday. Not in classrooms, not in hallways, not even in gymnasium rafters.

So unless there's a bat who slept right through the commotion and wakes up inside a school this weekend, the plan is to starting getting things back to normal at Bay Elementary and Clear Lake Ninth Grade Center, Polsen said.

At Bay Elementary, where more than 90 bats were caught and released last month, that means no more bat monitors patrolling halls and bathrooms during the school day. Kids can eat in the cafeteria again. The principal can move back into her office instead of stationing herself in the library to keep an eye out for bats.

At the Clear Lake Ninth Grade Center, where bats had been spotted in classrooms and the commons area last month, two gyms that have been closed to night-time practices should reopen.

Meanwhile, the school district's bat crew has been working to make other vulnerable schools bat-proof.

Polsen said bat activity was detected this week outside Wedgewood Elementary in Friendswood, and a crew will be working through to the weekend to make sure the bats stay outside. They're sealing up all openings larger than a nickel that a bat might squeeze through.

The same precautions have already been taken at Goforth Elementary and its neighbor League City Intermediate because there have been tell-tale signs of outside bat activity in that area as well. Clear Lake Ninth Grade Center's neighbor Clear Lake High School and Bay Elementary's next-door neighborhood Seabrook Intermediate have received the same treatment.

Joanne Moody, a naturalist with Harris County Precinct 1 and a volunteer wildlife rehabber specializing in bats, has noticed an increase this winter in the number of bats trying to share residences with humans.

Her theory: They're among the bats that would typically migrate back to Mexico in November or December and return in the spring. The sudden arrival of this winter's unusually low temperatures probably caught them by surprise and they had to find a place to hibernate quickly.

"There was this warm weather, and then, boom, they got caught," she said. "But that's just a theory."

With Mexican free-tailed bats -- the colonizing kind that have caused Clear Lake's schools so many problems -- a man-made structure is every bit as inviting as caves, Moody said. If they find a particularly suitable spot where no one tries to chase them off, such as Houston's Waugh Bridge, they don't even bother migrating. Many Mexican free-tailed live in the Houston-area year around.

Other species of bats have had to deal with an additional challenge on top of this year's cold snap, Moody said. Bats that live in trees -- palms are a favorite -- have struggled to find suitable homes since Hurricane Ike took a toll on trees.

With construction gobbling up their habitat over the last several decades, bats must look elsewhere, she said.