|
So Where Do the Bats Go?
By Heidi Richter
Kasanka National Park, in Central Province, hosts a
migratory
colony of straw-colored fruit bats that is the largest known
aggregation of fruit bats in the world, numbering an estimated 5-10
million.
Bat biologists have been intrigued with the colony ever since they
learned of its existence. Other than its large size, what makes
this colony so captivating?
The bats visit
Kasanka only during November and December, and outside of this time
period, the colony’s location is unknown. Millions of fruit bats
fly off into the sunset in December, yet no one has recorded another
colony of this size anywhere else in Africa. After seeing the
colony, multiple conservation biologists concluded that the identification
of roost sites and migration routes before and after Kasanka should
be a conservation priority.
Why are we so interested in where the bats visit?
Fruit
bats play an important ecological role in the regeneration and
dispersal of fruit trees by acting as pollinators and seed
dispersers.
Despite
long-standing
awareness of the potentially important ecological role of fruit
bats, we know critically little about the ecology of the vast
majority of species. Previous research at Kasanka determined which
tree species the bats most commonly use for roosting and foraging:
the wild loquats,
multiple waterberry species, and African mahogany trees. With
deforestation such a large problem in Zambia, and Africa in general,
a key issue for the Kasanka colony is the potential effect of
deforestation on foraging and roosting
sites.
Last December
researchers Heidi Richter and Dr. Graeme Cumming from the University
of Florida, USA used the first application of satellite telemetry to
track the movements of straw-colored fruit bats to document their
migratory route. Four adult males were fitted with leather collars
on which a satellite transmitter was mounted. These satellite
transmitters are solar powered with microminiaturized solar panels :
the fruit bats roost in trees allowing the transmitters to charge.
The transmitters emit a signal that is read by orbiting satellites.
These satellites can pinpoint the location of an individual bat to
within 150 metres. With internet access, data is available for
download within ten minutes.
Since December,
we have tracked the bats as they traveled up to 2,000 km away from
Kasanka. Previously it was thought that they may make long distance
movements as far as 1,200 to 1,500 km. We now know that this is not
only possible, but probably a lower limit. Some individuals flew
almost 200 km over only a few nights. After leaving Kasanka, all
the bats traveled to the Northwest, heading into the DRC and regions
further west.
Fruit
bats are thought to preferentially use the area next to rivers and
streams, which are rich in fruit trees and roosting sites, as
corridors. During their migration the bats were often
located within close proximity to water, supporting this
hypothesis. Further analysis of the data is currently underway so
that researchers may better understand the requirements of the bats
during their migration. This is another critically important
research area since in
Australia we know that some migratory fruit bats have only three
percent of their habitat protected in reserves. Straw-colored fruit
bats
will need a functional network of roosting and foraging sites;
preserving only one site on its migration route will not protect
this population.
Research
results will also be of relevance for the long-term sustainability
of forests and human livelihoods in one of the poorest parts of the
world. The potential contribution of the Kasanka colony to fruit
tree regeneration is particularly important in Zambia, where local
communities may be highly dependent on fruit, wood, and other forest
products. Around the world at least 289 plant species, producing
more than 448 economically valuable goods, rely on fruit bats to
some degree.
Support
conservation efforts and book your trip to Kasanka to visit the bats
at
trust@kasanka.com. For best viewing visit Kasanka from 5
November to early December. Visitors to the park say this is the
most amazing wildlife spectacle they have ever seen!
|
October
2006