Many others are endangered, such as the gray bat and the Indiana bat.

In the summer of 1997, more than 200,000 gray bats were counted at the cave.

Over the two decades of his study, he banded 40,182 gray bats at locations in six states.

His work proved the migration of the gray bat, but also began to show a decline in the population.

At dusk the air there is full of small grey bats who feed on the little worms.

One reminded Kirk of a huge gray bat, another brown vessel was wedge-shaped.

By the early 1980s populations of gray bats dropped to 1.6 million.

Less than 5% of all available caves are inhabited by gray bats.

Winter hibernacula are already cold when gray bats begin arriving in September.

Direct human disturbance and vandalism is the major factor leading to population decline in gray bats.