Bat colonies can reach truly enormous sizes, some with millions of bats pouring out to feed each night, and one cave in Texas has the largest of them all.

The big brown bat is the Adirondack’s largest bat; only the hoary bat is larger. The long, lustrous fur is brown. The ears, wing and tail membranes are black. Total length is 105-123 mm (4.1-4.8 in).

One of North Carolina’s smallest bat species is on the brink of extinction. But an unlikely ally is developing a plan to help save them — Albemarle Corp., the world’s largest lithium mining ...