Counting bats
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Counting bats

Wednesday, 06 July 2016
Counting bats

Every autumn the Seba's short-tailed leaf-nosed bats in the adventure tunnel between the Bush and the Desert are counted. The result of the count of 2015 is: 132 males, 150 females and 11 young ones, of which the sex is not yet known. In general more males than females are born, which can cause an undesirable gender ratio. 

Last year the counting took place in September, at which time 193 bats were counted. On October 29, 2015 the group had grown to 293 bats. In order to keep the group stable, the number of males is kept lower than the number of females. For that reason we started to place the 'excess' males as a group in the Bush in 2011. We did not place any females with them because then it becomes difficult to control the group. The group of males is well maintained, they found their own place and at night they fly around freely in the large hall. At the same time they fulfil a role in the pollination and spreading of seeds!

Not blood but mango juice

The Seba's short-tailed leaf-nosed bats are found in tropical deciduous forests and rain forests in Central America and in the northern parts of South America. There they live in caves, hollow trees and tunnels with several hundreds to thousands of them. At night the creatures fly out in large groups, sometimes with a few hundred at the time, to look for food. Many people think bats are scary: they bite and drink blood. However, this type of bat lives primarily on fruits, such as banana, mango and guava. Sometimes they also eat nectar or insects. They are also responsible for spreading many seeds and thus the growth of forests. These bats also use sonar to explore their surroundings. Their remarkable noseleaf, with which they produce the sonar beams, is flexible so they can make the sonar area wider and smaller. With it they can manoeuvre through dense forests with ease and direction. They do not find food with the help of their sonar beams, but by smelling it. 

Harems and bachelors

Harems and bachelors

The thousands of creatures resting in a cave together are subdivided into small groups. There are groups of bachelor males and harems of multiple females with one male. Day and night this male protects the females from intruders and other males. In exchange he has the exclusive right to mate with the females. After a gestation period of about four months a young is born that does not weigh more than a sugar cube. The female will carry the newborn with her at first until it gets too heavy. Then the young one will find a "place to hang" in the cave and remains there until it is weaned and can take care of itself. In general two times more males than females are born. This may explain the fact that males have a shorter lifespan than females. 

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