Kasanka

Throughout the world, one finds evidence of seasonal migrations in many different animal populations. Migratory bird counts in the United States, run by the National Audobon Society, involve hundreds of volunteer ornithologists. North American Monarch butterflies make a spectacular seasonal roost in Mexico, and the vast wildebeest migrations in East Africa are visited by thousands of tourists each year. These amazing movements of animals are important both economically and ecologically.

Here in Zambia, we are host to an equally amazing migration that draws a substantial number of visitors: the movement of millions of Straw-Colored Fruit Bats through Kasanka National Park. Many people travel to Kasanka in November and December to see the bats, and most ask the same questions: Where are the bats coming from, and where are the bats going to when they leave Kasanka? Before you travel to Kasanka to see this amazing sight for yourself, we would like to preempt your questions. This year the Kasanka Trust has invited a bat biologist to study their bat colony, answer these two questions, and educate about the importance and consequences of the bat migration to the ecology of the region.

Animals move for a reason – it is usually not an arbitrary decision to one day leave a site. Frequently, the driving force behind migration is a decrease in the availability of food where the animals currently are, or an increase in food somewhere else. To put it in terms easier for us to understand, let us use the analogy of our own food coffers. For example, if your refrigerator is empty, you may choose to go out to eat dinner, or accept an invitation to join friends at their home for a meal. Even if your fridge is well stocked, if your friends are hosting a holiday feast, you will be inclined to join them rather than eat what is on hand.

To understand why the fruit bats choose Kasanka, we need to understand the driving force behind the migration. This is where the ongoing research at Kasanka aims to contribute the most to the understanding of the migratory ecology of the species. The bats either are leaving something (changing climatic conditions, decreasing food resources) or are moving to something (most likely increased food resources).

We are currently trying to determine if the amount of fruit available in the park increases in tandem with the bats’ arrival. If so, the bats are most likely drawn to the area for food. At the same time, we will be tracking the depletion of food resources in the park. Most likely, the bats eat the available fruits until it requires a great deal of search time to find food. They then probably leave Kasanka for regions with a greater and more accessible food supply. If the bats leave when a lot of food is left, we are left with a lot of unanswered questions.

Why should you be interested in the migration of fruit bats? Populations of these and other flying foxes are threatened around the world, and it is important to understand the basic ecology of the species to establish effective conservation strategies. Scientists have shown that Straw-Colored Fruit Bats play a major role in the seed dispersal of economically important African trees. With deforestation a growing problem in Africa, shifts from native forests to agricultural fields can have serious implications for the food availability for this species. If we can understand the bats’ foraging ecology in relationship to key tree species, we will be one step closer to preserving our forests and related industries.

Populations are in decline, and areas that once had large numbers of bats (for example Kampala, Uganda) now find it difficult to spot colonies. This migratory colony potentially covers thousands of kilometres during its migration phase, and the prospective loss of this resource has implications for a significant portion of Africa. When such a unique resource as the Kasanka bats has been identified, it is important to do whatever is necessary to conserve it.

Viewing the bats at Kasanka National Park is an unforgettable and unique experience. You can do your part toward conserving the bats by supporting the colony with your visit. The bat colony can be observed at Kasanka from late October through to early January, with peak viewing occurring mid-November through to mid-December. Contact park@kasanka.com (ph. 00873762067957) for bookings.