The croaking of a raven is considered in Russia and Servia as foreboding the shedding of blood.[20] The ancient tradition of the singing of the dying swan is familiar to everyone. Although our common swan does not produce sounds which might account for this tradition, it is a well-known fact that the wild swan (_cygnus ferus_), also called the whistling swan, when on the wing emits a shrill tone, which, however harsh it may sound if heard near, produces a pleasant effect when, emanating from a large flock high in the air, it is heard in a variety of pitches of sound, increasing or diminishing in loudness according to the movements of the birds and to the current of the wind. With the idea of the song of the dying swan appears to be connected the Scandinavian tradition of the Valkyrjas, who were maidens in armour with wings of swans. During a battle the Valkyrjas approached floating through the air, and hovering over the scene of carnage, they indicated who were to fall in the fight.[21] The cuckoo is regarded by the Russians and by most other Slavonic nations as a bird of sadness. According to a Servian tradition the cuckoo (called _kukawiza_) was a girl who wept so continually for her deceased brother that she was transformed into a bird, which in two melancholy tones sends its unabating complaint through the air. A Servian girl who has lost her brother (lover?) never hears the cuckoo without shedding tears. Moreover, in Servia the cuckoo is considered as a prophetic bird, especially by the _heyduk_, or robber, who augurs from its earlier or later singing.[22] Among the Germanic races the notes of the cuckoo, when in the spring it first makes itself heard, are generally considered as a good omen. It is still, as from Teutonic mythology it appears to have been in ancient time, a belief among the peasantry in Germany that if anybody counts the number of times this bird repeats its call, he may ascertain from it how many years he has still to live, or how many years will elapse before an event comes to pass which he has reason to expect. There is an old story told of a person who, having led a rather wicked life, in order to atone for it resolved to become a monk for the rest of his life. It happened that, just as he was entering the monastery, he heard the cuckoo crying its name the first time in the spring. He anxiously counted the number of calls; and finding them to amount to twenty-two repetitions, he at once changed his mind. "If I have to live twenty-two years longer," he argued with himself, "I may as well enjoy twenty years longer the pleasures of this world, and then I shall have two whole years left to denounce its vanities in a monastery." So he at once returned to the world.