Subscribe | UPI Odd Newsletter Subscribe July 16 (UPI) -- A worker at a Houston high rise captured video of an unusual sight outside one of the building's windows -- dozens of bats gathered in a swarm on the wall. Dave Rojas, who works in an office at the building, tweeted a video showing dozens of bats gathered together to roost right outside a window. Advertisement Rojas said the building is an annual hub of bat activity. "Every year the bats make a visit to our office. It must be that time of the year again. I think they are migrating," he wrote. Read More Texas Walmart summons specialist to get rid of swooping bats Swooping bats surprise shoppers at Texas Walmart