Baby Eagles

After the fall of Constantinople, the Russian Empire took the two-headed eagle as its own symbol.
After his crowning as the new Roman Emperor, Charlemagne adopted the ancient Roman eagle as his own symbol. The Holy Roman Empire born of his kingdom took the eagle, but the Habsburgs replaced the golden eagle by an imperial eagle. From this derives:
The Austrian Empire had a two-headed eagle as its symbol. After the abolition of Austria-Hungary, Austria took as its symbol a one-headed eagle in the modern coat of arms of Austria.
Prussia, and later Germany have used a black eagle as their national symbol.