Millions of straw-coloured fruit bats have begun their annual descent upon Zambia’s little-known Kasanka National Park, creating what is considered the largest mammal migration on Earth.
An estimated eight to 10 million bats (Eidolon helvum) gather in the park between late October and December, drawn from across Central Africa by a seasonal explosion of fruit, reports BBC.
The scale of this event is eight times larger than the Serengeti Great Migration, yet it remains an overlooked spectacle; while the Serengeti attracts up to 700,000 visitors annually, only around 800 people witness the Kasanka migration.
Migration plays a vital role in regional reforestation. According to Frank Willems, former chief ecologist at Kasanka, the bats consume their own body weight in fruit each night, with the entire colony putting away approximately 230 to 250 tonnes of fruit in a single evening. Over the course of their stay, they consume an estimated 330,000 tonnes of fruit, primarily wild loquat, milkwood, and waterberries.
Helen Taylor-Boyd, a Zambian bat ecologist and board member of the Kasanka Trust, noted that these bats are exceptional seed dispersers. “In fact, they’re capable of dispersing seeds further than many vertebrates studied, including elephants,” she said.
A mysterious journey
Despite the sheer volume of animals, their exact migration routes remain largely unknown. Biologist Heidi Richter previously used satellite tracking to discover that individual bats can travel vast distances; one bat, named Hercules, was recorded flying more than 2,400 kilometres.
Taylor-Boyd explained that researchers are only just beginning to understand where the bats originate and where they go after leaving Kasanka in January.
Kasanka National Park, one of Zambia’s smallest at 390 square kilometres, was at risk of losing its national park status in the late 1980s due to heavy poaching.
Its recovery began in 1990 when David Lloyd, a former British colonial officer, used his own funds to build roads and camps. Since then, populations of puku, sable antelope, and elephants have returned.
The park is also a premier destination for birding, with over 450 species recorded, and serves as a sanctuary for the sitatunga, the continent’s only truly amphibious antelope. An estimated 500 to 1,000 sitatunga reside in the park’s papyrus swamps.
Located approximately 500 kilometres north of Lusaka, the park is managed by the Kasanka Trust. Visitors typically stay at Wasa Lodge or self-catering sites like Pontoon Camp.
Observation of migration is primarily conducted from raised platforms, including the 10-metre-high Musola Hide and Vivienne’s Hide. Travelers are advised to bring binoculars and warm clothing, as evening and pre-dawn viewing can be chilly. For those lucky enough to witness the event, the experience is described as standing inside a “living storm” as millions of wings fill the sky at dusk.
