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Anyone who’s often around old ruins will certainly catch sight of the greater mouse-eared bat flying past. This biggest indigenous species of bat feels just as much at home among the roof beams as it does in field and forest. The experts at the Fressnapf specialist retail chain paint a brief portrait of this unusual life form here as the German Speleological Federation (Verbena der Deutschen Höhlen- und Karstforscher) has nominated the mouse-eared bat as Cave Animal of the Year 2011.

The greater mouse-eared bat with its wingspan of some 40 centimetres is largest of its kind in Germany and in Europe. Its name is no accident as its three centimetre-long ears look enormous compared to its (maximum) eight centimetre body.

Mouse-eared bats are considered cave dwelling-animals as they hibernate underground. From the end of October they move into consistently cool but frost-free and humid retreats such as caves or old mine workings. When the temperature drops below a specific level, they fall into a state resembling sleep whilst hanging upside down. To save energy, they match their body temperature to their surroundings and reduce their metabolism. Incidentally this "hanging", so typical of the bat, requires no energy at all because the toes on their feet have a locking mechanism.

In the springtime, the mouse-eared females move into quiet building complexes such as the large attics of churches, castles, manor houses or farmhouses. There, they form so-called nursery roosts which can consist of several hundred bats. Giving birth to their (at most) two young is also a balancing act as this, too, takes place "hanging". The female switches mainly to the hanging position with the head up in order to gently catch her naked and blind newly-borns in her tail flight skin. From there, the little ones immediately clamber up the fur to the teats where the stick fast. When the young become independent – after around 40 days – the mouse-eared mothers leave their quarters to return there next spring.

The basic diet of the greater mouse-eared bat consists of ground beetles. Being pure insect eaters, they also feed on nocturnal butterflies, grasshoppers, spiders and crickets. They can orientate themselves without any difficulty while they fly low over the ground through deciduous and mixed woodland in search of their prey. In so doing, they send out cries in the ultrasonic range through the mouth, which are reflected off objects like an echo. They pick up this echo with their ears and use this information to create a mental picture. When they sense an insect, they land, catch it with their powerful jaws and usually eat it as they carry on flying.

Since the 1950's, the numbers of mouse-eared and other bat species have shrunk drastically due to the ever decreasing near-natural landscapes and shelter options available to them. In order to protect them you, as a house owner, can create a near-natural garden ideally with night-blooming plants and shrubs, leave small flight-holes into your attic or put up bat nesting boxes on a tree.

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Silently through the darkness The "greater mouse-eared" is Europe's biggest species of bat and “Cave Animal of the Year 2011”. Photo: Fressnapf /Ulrike Schanz (Photo printout only in association with the editorial text.) Download (1081 KB)