In 1997 a small group of Pennsylvania Game Commission wildlife surveyors and Pennsylvania Turnpike Commission employees stood at the mouth of an abandoned turnpike tunnel. Ushered inside by the blustery winter afternoon, they found the interior of the tunnel just as frigid, but at least it gave them shelter from the snow. Powerful spotlights slice a bright swath while panning across the smooth interior, occasionally illuminating a rusted relic of yesteryear. A broken light fixture, a dented panel storing nothing, and often times a big brown or two.

Abandoned Pennsylvania turnpike and railroad tunnels will never replace abandoned mines or natural caves as a major diverse winter bat hibernacula. Only certain species put up with the cold, breezy, and sometimes dry surroundings. Nevertheless, they are every bit worth checking and the man-made structure of this particular tunnel allows biologists to tinker with the environment in hopes of making the site more suitable for bats.

Several tunnels along the Pennsylvania turnpike's snake-like route through the Appalachian Mountains have been abandoned for 40 years in favor safer routes over mountains instead of through them. This particular relic is nearly a mile long and thirty-five feet wide and twenty feet high. The tunnel is only two lanes, once forming a severe bottleneck before the present-day five-lane detour was complete. Just inside an old ice-covered staircase leads up to the fan room. Here the remains of two huge mine fans sit idle, patiently collecting rust. With some effort due to the immense weight, the fans could be spun by hand, still smoothly gliding on its bearings.

The fan room has a central door which leads into a dark, dusty corridor directly overlying the road tunnel below. The tunnel as it stands is slightly too cool and dry to be considered an optimum hibernacula. The species which put up with these less-than desirable conditions are big browns and small footeds and can be found here along with an occasional little brown. Turnpike officials have attempted to cut down on the breeze somewhat by simply keeping the rusty door leading to the fan room closed.

An usual problem exists for bats attempting to use these tunnels. While the animals have no problem clinging to something as fine as the ridges in a person's fingerprint, they are hard up to find any surface rough enough to roost on inside the tunnel. By looking carefully we can find tiny scratches scraped into the years of soot built up on the tunnel's walls, apparently caused by bats attempting to land and finding the surfaces too smooth. Bats can be found clinging to anything rough enough which is in the proper temperature zone, sometimes even using old electrical tape on a pole as a platform.

The experiment

In 1997 artificial 3/4'' wide crevices made from cement board were installed in strategic places along the tunnel, based on previous observations of bat locations. At each station these baffle sets were placed both parallel to the airflow and perpendicular to the airflow.

During the winter of 1998 the tunnel was surveyed and found a few bats accepting the new roosts, but we expect it will take several more seasons of observations before the project's results can be understood. This site will be resurveyed in February 1999, see our Winter Survey section for the latest update on this project.