SAN JOSE (dpa) – Horrible, nasty, ugly things – bats and especially South American vampires with their incisor teeth instill terror in most people yet for biologists these nocturnal creatures with their ultrasonic navigation skills are some of the most fascinating on the planet.
Bats have unusual skills and a host of unrevealed secrets which is why German scientists Detlev Kelm has spent the past two years in the tropical rainforests of Costa Rica researching the habitat and habits of the bat. He sees it as a contribution to maintaining the teeming variety of wildlife in the rainforests.When dusk descends on Braulio Carrillo national park and the heat of the day recede, the flutterers come out to play. All kinds of bats come forth from trees and caves, weaving their way between the trunks of the forest giants and across clearings in search of food.Most of them devour wild berries and some – like the dexterous humming birds – drink nectar from flowers and plants, others hunt for frogs. One type of bat even specializes in flitting to and fro across rivers and ponds where it plucks small fish from the water.“Costa Rica has more than 100 different types of bat compared to Germany which has only 30. Most are like mice, shy and absolutely harmless,” said Kelm who was commissioned by Erlangen University to study bat lore at Costa Rica’s La Selva research station.“Nevertheless animal breeders and health authorities are wary of the few bat species which do drink blood,” said Kelm. These vampires sail down to the pastures, biting the legs of cattle and licking off their blood.“This can lead to the spread of diseases like rabies,” said the expert.Kelm keeps a sharp lookout for bats day and night. During the day he roams the rainforest looking for hollow trunks and bat caves.He identifies the various species – who often live together in a bat cave “communes”, installs infra-red cameras in order to observe in the dark undisturbed and compiles a video record of their life cycles and activities.At night he traces their flight paths using night vision equipment. He also catches some animals using fine nets which spare their delicate wings. Kelm fits these with miniature transmitters which provide further data which can be evaluated using computers.“They really have amazing abilities. Apart from ultrasound which they use to orientate themselves in the dark, they seem to have fantastic memories. It seems they make a mental note of every single bloom in their neck of the rain forest and can fly there blind in order to drink nectar.”The level of energy efficiency shown by several bat species is also astonishing. During the day and in adverse weather conditions they seem to fall into a semi-comatose state, enabling them to survive with fewer nutrients than other comparable animals.“We can learn all sorts of things from bats,” said Kelm, 29. Yet bats are endangered in Costa Rica: there are not enough mature trees for them to make their homes. In Costa Rica the rainforests are still being felled to make way for cattle-grazing land.Superstition and an exaggerated fear of vampires also play a part in eradicating the bats.Few people realize what a valuable role bats play in maintaining the diversity of species in the rainforest. The bats pollinate hundreds of types of plants, a task performed by bees and other insects in Europe and other temperate climates.Flora and fauna here have adapted to each other. Many bats have developed exceptionally long tongues and can hover like humming birds in order to extract nectar. Some plants are designed to attract bats and bloom at night only.Many rainforests plants are able to multiply only because the bats eat their fruit and leave behind the seeds in their droppings. All this helps maintain the rich diversity of plant life in the rainforest.Both flora and fauna at La Selva,some 90 kilometres from the capital San Jose, are fascinating. In the national park, howling moneys live alongside languorous sloths, raccoon-like coatis and even jaguars.Various poisonous snakes such as adders force researchers and scientists to exercise great caution during their nocturnal and daytime patrols.La Selva is sponsored by two dozen U.S. universities and usually around a dozen biologists from the U.S. live and work at La Selva engaged on various tropical projects.The only German scientists currently here are those from Erlangen. Detlev Kelm, who comes from Hamburg and used to study wolves in the wild in Portugal, works with the Institute for Zoology in Erlangen.In order to provide some practical help to the bats and not just observe them Kelm has devised a custom-built nest for “homeless” tropical bats. The first of the man-sized boxes are already occupied.They are cheap to make from cement and sawdust and even sceptical cattle breeders have been convinced that these are the haunt of “harmless” bats and not blood-sucking vampires.
