On 17 April, International Bat Appreciation Day flips its cape to the planet"s night shift: bats. With more than 1,400 species on every continent except Antarctica, these winged mammals keep ecosystems balanced. They"ve been on Earth for over 50 million years, and only three species are true vampires. Found only in the Americas, these bats feed on blood, while the rest survive on insects, fruit, nectar or pollen. In Texas, Bracken Cave can host up to 20 million Mexican free-tailed bats in summer. Many gulp crop pests, cutting pesticide use; others pollinate wild agaves and disperse seeds that help forests rebound.