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.

In today's image, a grey-headed flying fox mother in Yarra Bend Park, Australia, carries her pup. One of the country's largest bats, she can span over a metre, navigates by sharp sight and smell—not echolocation—and flies up to 50 kilometres for figs and blossoms. Batman is fictional; the real bat-signal is conservation, as habitat loss and disease are shrinking populations.