Located on the edge of the Bangweulu Wetlands, Kasanka National Park, the smallest and one of the lesser-known national parks in Zambia, is nonetheless a gem for wildlife lovers, home to a diverse array of habitats and animals. The high number of pans, papyrus swamps, dambos, and floodplains makes Kasanka an especially good haunt for birders, with more than 400 avian species recorded in the park.

What the park is most notable for, however, is the enormous annual bat migration. Between November and December each year, some 5 million to 10 million straw-colored fruit bats (Eidolon helvum) descend on the park to feast on the area’s musuku, mufinsa, and other fruit trees. Scientists are not sure exactly where the bats spend the rest of the year, though they are known to come from deep in the Congo rainforest.

Visitors hoping to catch a glimpse of this thrilling sight are led on guided tours to various tree hides in the park during the dawn and dusk hours when the nocturnal creatures are especially active. There are so many bats that they darken the sky. The sheer number of bats makes this tradition one of the largest annual mammal migrations on the planet.