Common cuckoo of two years. More than 100 host species have been recorded: meadow pipit, dunnock and Eurasian reed warbler are the most common hosts in northern Europe; garden warbler, meadow pipit, pied wagtail and European robin in central Europe; brambling and common redstart in Finland; and great reed warbler in Hungary. Female common cuckoos are divided into gentes – groups of females favouring a particular host species' nest and laying eggs that match those of that species in color and pattern. Evidence from mitochondrial DNA analyses suggest that each gene may have multiple independent origins due to parasitism of specific hosts
Everything which is not forbidden is allowed forbidden is compulsory." This quote has been suggested as a principle of physics. The claim that “everything which is not fobidden is allowed” is a principle only of English law does not stand the test of reality. In fact, it is a common principle of liberal democracies. In Germany, it has constitutional rank under Art. 2(1) of the GG which protects the general freedom to act (Allgemeine Handlungsfreiheit), as demonstrated e.g. by the judgment of the Bundesverfassungsgericht known as “Reiten im Walde” (BVerfGE 80, 137). Everything which is not forbidden is allowed "Everything which is not forbidden is allowed" is