Bats Enter the Fashion Stakes

Some select groups of fruit bats in the Kruger National Park are now wearing trendy bead necklaces. However, the bats are not personally choosing these fashion accessories, they are being fitted by two American scientists working in conjunction with the park's scientific services, who are studying the behaviour of these large flying mammals.

Each of the bats in the study will be fitted with a unique combination of coloured rings, in a collar that has been specially designed to cause the least risk to the bat while it flies and feeds.

Other bats in the study are getting more high-tech accessories - small radio collars designed to fall off within six months. The collars weigh only a few grams, less than five percent of the mass of the bat, which is critical to the collar not affecting the bat's activities.

The bats chosen for the study are large fruit-eating bats, Wahlberg's and Peters' Epauletted bats. The main researchers, John Winkelmann and Frank Bonaccorso, are hoping to find out more about what fruit bats eat in the dry months when few trees are fruiting.

They will also find out what the bat's home-range is, and how and when they go out to eat. They are especially interested in the relationship between the bats and the common cluster fig (Ficus sycomorus or gewone trosvy) which is one of the few trees fruiting in the winter months.

This tree has been of concern to the park authorities as there have been few new trees sprouting since floods harmed the fig population a few years ago. The figs usually grow along the major rivers in the Kruger Park.

Bats are important to the fig trees as they help spread the seeds to new areas as they defecate on their nightly trips from tree to tree. The study is going to concentrate on bats from Skukuza and Shingwedzi, where the bats feed in the trees growing along the Sabie and the Shingwedzi rivers respectively.

The good road networks in these areas will allow the researchers to radiotrack the bats easily from cars. Previous work has shown that the bats can travel as much as four kilometres along the Shingwedzi River in a night. Marked bats can be spotted under the thatch at the Skukuza shops and the takeaway at Skukuza.

However, the researchers are hoping to see if the bats have other roosts, and are also looking for other roosting sites around the park. Scientific services has enlisted the help of field rangers to find new roosts, and sharp-eyed members of the public can also report roosting sites to Andrew Deacon, who is liasing closely with the American researchers.

The study will continue both this year and next year. Both bat species occur in the northern parts of the park, and they are so similar that the only way to tell them apart is to shine a light onto the roof of the bats' mouths to check the shape.

Having previously studied bats in other parts of the world, especially Papua New Guinea, the researchers say that it takes less than thirty minutes to catch a bat in a mist net, weigh and measure it and fit a radiocollar. For the bats with the trendy necklaces, they can be fitted in less than a minute while one person holds the bats and the other attaches a prepared collar.

The collars can then be used to identify the bat from a distance with binoculars, which decreases the amount of human activity at roosting sites. Other aspects of the relationship between the bats and the figs will also be studied, and eventually a computerised database of the location of both bats and fig trees will be compiled.

By Melissa Wray

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