WHAT MAKES BIRDS BACK TO THEIR NEST.

Birds have impulses that govern their life. His movements, which seem to be capricious, are developed from two moments: that of evasion and that of filing. Both impulses seem to be that they are contradictory, nevertheless before a certain situation these are used to adapt to that situation in the most convenient way. To better understand, let us take as an example the choice of the nest or rather the choice of the habitat area where the nest is. At one point in his life the bird spends its days in a reduced perimeter around the nest, it is there where it builds the cradle of its children, there it incubates and breeds. Once you have met your species the bird returns to travel on its migratory route. Months pass and one day he returns to the same place and that is how his life once again oscillates between these two impulses: filing and evasion. For example the European nightingale with area of ​​dispersion throughout the continent emigrates annually, when arriving in autumn. Flying in the evenings, some go to Abyssinia, others to the shores of the Red Sea, the banks of the Nile, the gardens of Arabia. There it enjoys a pleasant climate, but when the first spring breezes sweep the snow and open the flowers in the gardens of Europe, the nightingale leaves for days and nights flapping its wings over the desert defying the fury of the elements. Your goal is simple: to get to the same tree where you were born. If it is a question of individuals who were born in England, for example, after crossing the Mediterranean it never stays in the Italian countryside, in the French vineyards, or in the orange trees of Valencia, where it could find better conditions to do so, to England to his tree that saw him born. What is said for the nightingales is also valid for swallows, charlatans and chorlos. In Greece happens with the stork and the crane and in Latin America the same happens with the tijeretas, churrinches and the corbatitas. But also those birds that parasite the nests like the cuckoo. It is believed that the hereditary heritage of the species (its instinct) is the one that reveals where they were bred successfully and where the best conditions exist for them, in turn, to recreate their mating and nesting cycle. All this is due to the so-called 'mnemo', something like a secret memory of the ignored paths that awakens on its sleepy memory, stimulates the bird to return to its tree. This 'prenatal' memory causes the birds to return to the place where they must have been born, I say, because they once tried to repopulate with nightingales in the forests of northern Scotland and every precaution was taken so that the attempt would not fail. It was believed that the chicks acquire, while in the nest, a sensitive impression of the topography of the place where they were born. To avoid this, eggs were collected where birds were abundant and placed in robins' nests where they were incubated and later reared without any inconvenience. The time of migration arrived and the nightingales took the route of their species but never returned to the north, but to the place where they must have been born! As we see, there is part of the behavior of the birds that can be explained rationally and another part that is not and that is pure mystery and that mystery is the one that fascinates us much more to those who love the birds and it is we who must have the responsibility to respect these habitats so we can continue to enjoy the song of all the species that make up this biodiversity of birds.