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Going Batty
Old (read that as
‘having read The Lowdown for a number of years’) will recall that
each year at this time, we have featured articles on the arrival of
thousands, nay, millions of straw coloured fruit bats, Eidolon
helvum, at Kasanka National Park. And twice now, I have been
lucky enough to visit Kasanka to see these creatures for myself and
to chat with the many researchers who are also visiting on this
fascinating subject.
Sadly, this year,
I have not been able to travel there, but have received a short
piece from P.A. Racey, Regius Professor of Natural History in the
Department of Zoology at the
University of
Aberdeen:
 Every
year at about this time, thousands of straw coloured fruit bats
arrive at Kasanka and take up residence in trees in the Mushitu
swamp forest. The numbers build up to a peak in November when
several million individuals are thought to be present. They remain
until late December or early January and then depart. Such large
roosts are known in other parts of Africa, often in urban areas as
for example in Dar es Salaam, Kampala, Accra and Abidjan, although
the numbers of bats in these roosts are reported to be declining.
Straw coloured fruit bats are also known to be migratory, moving
north and south of the central belt of
Africa in
search of food. That is what is happening at Kasanka, where the
bats feed on the abundance of fruits such as waterberry and wild
loquat which are
present at this time. Both males and females are found in the roost
and the females are either pregnant or suckling young, so the
abundant fruit must help them meet their increased energetic
demands.
Where the Kasanka
bats come from is a mystery since no such large colonies have been
reported in the forests of the Democratic Republic of Congo, the border of which is only thirty kilometres north of Kasanka. To
answer this question will require satellite telemetry and we are
seeking funding to have a few tagged (at £2,500 each) to carry out a
pilot study.
Fruit bats such
as Eidolon are important pollinators and seed dispersers in
Africa. The
baobab Adansonia digitata relies on Eidolon for pollination, and
small seeds, such as those figs, pass rapidly through the bats
unharmed and are distributed over wide areas.
To see the
millions of bats at Kasanka dispersing at dusk against the setting
sun is one of the wildlife wonders of Africa. However, we need to
find out more about them to ensure that they are not threatened in
those places where they spend the majority of the year and continue
to return to feast in Kasanka's woodlands and enthrall future
generations of visitors.
Enthralling
certainly describes this spectacle and for those who have a couple
of days to spare, I would certainly recommend that you try to get up
there during December before the bats disappear for another year.
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December 2004