Hello October. Goodbye bats.
The foothills west of Boulder are home to 11 different species of bats — more than a quarter of all the kinds of bats that live in the United States — including several sensitive species like the Townsend’s big-eared bat.
But just as local store windows begin filling up with Halloween costumes, Jack-o-lanterns and cobwebs, Boulder’s spookiest natural decorations (bats) are flying to higher elevations in search of the perfect place to hibernate: no so cold that the bat freezes, but cold enough for the bat to stay in it’s low-metabolism slumber.
Today is the last day of summer cave closures for roosting bats on Boulder open space land. Both the Mallory and Harmon caves, accessible from the NCAR trail head, are open to hikers and explorers starting tomorrow.
During the summer, the two caves are closed to protect colonies of mamma Townsend big-eared bats that are raising their pups. All summer, the mothers feed on insects and sip water at night before coming home to nurse their protected young. But once the pups try to fly on their own, it’s not always very pretty.
“The young are clumsy and awkward, and they get tired,” said Rick Adams, president of the Colorado Bat Society. “If they get too tired, or they hit a tree and fall, they end up on the ground. There are carnivores of all kinds that know where the bat roosts are.”
A baby bat resting on the ground is a treat too hard to turn down for a hungry skunk or coyote. In fact, surviving on their own is so hard for baby bats – they have to coordinate their flight, metabolic rates and a sophisticated echolocation system – that only 60 to 90 percent of the pups survive the first year. Those that do head to higher ground with their moms to sleep through the winter.
The population of bats in Boulder has been on the decline. The flying mammals are dependent on water sources to survive, and hotter, drier summers have scientists concerned about what climate change may mean for the future of Front Range bats, Adams said.