Many birds such as starlings, cranes, and swallows migrate to the south in autumn because they do not find enough food in winter. It is not good to feed the birds because it may disturb their regular habits of finding food for themselves. Their destination and the migratory path is the same every year. For years, scientists puzzled over the birds’ ability to take exactly the same path every year but now it is assumed that birds possess a ‘magnetic sense of direction’ and orient themselves to the magnetic field of the Earth, using the position of the sun during the day, and the stars at night.
Moles spend a large part of their lives in a self-dug burrow system below the ground. The animals push the loose earth that is a result of digging to the earth’s surface after every 50-100 cm. The result is a typical molehill, about 20 cm high. Sometimes we also come across huge hills with air holes all around. Below these molehills the moles make a nest in which they give birth to their young ones. 
A lot of activities are carried out in our gardens by animals and insects living underground, such as moles, rats, and earthworms. Upon a closer look, we can also find animal tracks on the leaves of the spherical oak-apple tree or the fine webs with which spiders catch their prey. Besides the animals hidden underground, there are birds that chirp and fly around in the gardens. 
‘Survival of the fittest’ describes the evolution theory of Charles Darwin. In the struggle to survive, the species that are healthy, strong, and have adapted themselves best to their environment will win. They ensure their survival through healthier genetic material that is passed on to their offspring. Thus, a giraffe with a longer neck can reach leaves high on the trees to feed himself. While a giraffe with a shorter neck may stay hungry, since he has access only to the leaves lower on the tree. Eventually, the hungry giraffe may become so weak that he falls prey to lions. 
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