The species composition in the European Alps is very heterogeneous and has only developed in recent geological time. The Pleistocene glaciation repeatedly covered the whole Alpine range with ice so that the Alps were free of mammals during several periods. Some invertebrates could survive on single mountain tops (so called nunatakkers) that remained free of ice. After the retreat of the last glaciation about 10′000 years ago the colonization of the Alps began.

In this different mechanisms acted together:

• Together with the advancing glaciers, species like the mountain hare (Lepus timidus), that were present only in the north before the ice ages, migrated into Central Europe during the last ice age. Because of the warming of the climate in Central Europe, some cold loving animals followed the retreating ice bodies northwards. Other animals migrated to higher altitudes and so colonized the alpine zones.



• Also during glaciation, large grass steppes spread from Asia to Central Europe. These steppes were excellent habitats for species like the marmot (Marmota marmota), which came to Europe at that time. After the climat became warmer and the glaciers retreated, forests displaced and fragmented the grassland steppes. Some marmot populations also retreated eastward but others remained in the European steppe habitat that was incrementally displaced upwards by forests and today is found mainly above the timberline.

1 - Actual arcto-alpine distribution of the mountain hare (Lepus timidus)

2 - During the last ice age, the marmot (Marmota marmota) lived in the steppes of Central Europe. Through dispersion of forest, marmot populations were pushed back to the steppes of Eastern Europe and Asia as well as to the alpine steppes.

• Across the contiguous mountain range from the Himalaya, over the Ebrus, Taurus, Kaukasus and Carpathian mountains, animals migrated from the Asian region into the Alps. The chamois (Rupicapra rupicapra), for example descends from a form of wild goat that lives in the Himalaya mountains. In the same way, many alpine birds presently found in the European Alps migrated from the Himalaya region to Europe.

3 - Along mountain ranges alpine species colonise new regions.

• In contrast to the mammals, some invertebrates survived glaciation on ice-free mountain tops. These mountain tops acted as refuges and functioned like islands in the body of ice masses. As a consequence of this insular distribution, invertebrates show the highest rate of endemism among animals in the Alps. After the retreat of glaciers, the colonization of the alpine zone by invertebrates happend first from the top down by invertebrates surviving on insular mountain tops and only second from invertebrates of the surrounding low lands.

The colonisation of the European Alps is still going on. Today animals are driven to retreat to higher elevations mainly following habitat loss due to human activities. Though large carnivores like wolf, bear or lynx today live almost exclusively live in higher elevations, they were not formerly typical alpine animals. One or two centuries ago they populated the lowlands as well as the mountains. Through the extension of the urban areas and the increasing activity of humans in the lowlands they withdrew to less disturbed areas - the mountains.

29 August 2011
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