Pythons could slither wild over lower third of America.

Nation: Hold on to your cats and dogs.

As climate change warms the nation, giant Burmese pythons could colonize one-third of the USA, from San Francisco across the Southwest, Texas and the South and up north along the Virginia coast, according to U.S. Geological Survey maps released Wednesday. The pythons can be 20 feet long and 250 pounds. They are highly adaptable to new environments. Two federal agencies — the USGS and the U.S. Fish and Wildlife Service — are investigating the range of nine invasive snakes in Florida, concerned about the danger they now pose to endangered species. The agencies are collecting data to aid in the control of these populations. They examined Burmese pythons first and, based on where they live in Asia, estimated where they might live here. One map shows where the pythons could live today, an area that expands when scientists use global warming models for 2100. "We were surprised by the map. It was bigger than we thought it was going to be," says Gordon Rodda, zoologist and lead project researcher. "They are moving northward, there's no question."