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BATTING FOR KASANKA!!
The mammal books will tell you that this is a sociable species occurring in colonies of up to a few hundred thousand, but the Kasanka spectacle has been consistently estimated to be between 5 and 20 MILLION individuals. The sheer number and that fact that they are observed to arrive and depart in distinct groups over a couple of weeks, clearly shows that this is not one roaming colony but a gathering of many. Visitors lucky enough to be in Kasanka at this time always have the same 2 questions.
1. Where do these bats come from and where do they go?
2. Why do so many bats all come to this one little spot in Zambia?
Over the past 7 years most of the world’s top bat Scientists have been to Kasanka but they have failed to come up with conclusive answers to these questions. The person who has put the most time and effort into the Kasanka bats is Heidi Richter, an American scientist who is now working on a Phd following her MSc 2 years ago. We first met Heidi on the side of the road in Chisamba when she was a Peace Corps volunteer looking for a lift! At the time we already had a Brown necked Parrot in the car which we had confiscated from the roadside “sellers” and so a biology student seemed a useful addition to the passenger manifest. When we started chatting we found out she was one of a growing group of biologists around the world who are obsessed with bats, and that was the start of Heidi’s involvement in the Kasanka bats.
This year we are hoping to make some real progress on the first big questions of where they come from and where they go, because Heidi has secured enough funding to fit 4 minature GPS satellite transmitters. When this method was first proposed in 2000 it was not only the considerable cost that had to be overcome, but the fact that the lightest units available which would last for 12 months were then were still too heavy to be fitted to these bats. Hence we have had to wait some years for technology to catch up with our ambitions. Bats are not as strong flyers as birds and so the recommended percentage of body weight for any device to be attached is less. Indeed bats have quite a few limitations due to their relatively late evolution into flight. It’s said that these bats cannot fly in the sun as they overheat! As long as the satellite tracking goes according to plan we should get some idea of where the bats disperse to feed each night and where they spend the rest of the year. We’ll be posting updates on the kasanka website www.kasanka.com Ideally we would like to collar about 20 or 30 bats next year to get an idea of the full range of the bats but that will depend on the success of this year’s trial and finding the funds!
The second question of why so many bats should all come to one place remains a mystery. An early theory was that it was a gene exchange but the colonies have been observed to be at all different stages of the breeding cycles with some mating, some in early pregnancy, some late, some with young. It’s known from observation of individual colonies around Africa that these bats are very seasonal and synchronised in breeding, so the diversity seen in Kasanka implies that they are coming from a wide area. These bats are mainly recorded around the edge of the Equatorial rainforest, but no-one yet knows if large colonies live deep inside the rainforest, so the satellite tracking research may reveal interesting information on the species as a whole. Another theory that still needs looking at is that the Kasanka area offers a “super-abundance” of fruit in November and December which is just too good to miss out on. Yet another theory is that fruit around Kasanka contains some vital minerals which the bats need. More work is definitely needed on this burning question.
You may ask why scientists and ecologists are so interested in these unusual mammals. The answer is that fruit bats are known to be by far the most important dispersers of seed for the forests, and their health is therefore linked to the survival of the world’s great rainforests. Against this observations have shown that fruit bat numbers are in serious decline in many places due to loss of habitat and hunting for food. Luckily the Lala people living around Kasanka do not consider roast bat such a delicacy as their distant relations in West Africa!
There are a lot of other fascinating aspects of the Kasanka bat colony such as their relation with the small forest they roost in. As well as dropping huge amounts of fertilizer they also pull off large branches with the sheer weight of hanging bat! Predators like birds of prey, crocodiles, bushpigs, snakes and even the odd leopard are all observed “swarming” in for easy meals!
One thing remains certain. The sight of these
bats flying out of the forest to forage at sunset is one of Africa’s
great wildlife spectacles which can only be appreciated when seen in
person. Treat yourself to a visit to Kasanka any time before
Christmas and you won’t be disappointed! It’s also a great time for
birds, flowers, butterflies and game viewing. Bookings can be made
through travel agents or by email to
Edmund Farmer, Park Manager, Kasanka National Park.
Back to December 2005 Newsletter
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It’s
that time of year again when a small patch of “mushitu” evergreen
forest in northern Zambia receives the world’s biggest gathering of
Fruit Bats. Quite why so many of these Straw-coloured Fruit bats
Eidelon Helvum congregate in one group for 2 months every year
is still a mystery. 
The lodges in Kasanka are open all year.