Cuckoo are slightly different from other birds. They are known for their selfish nature. They don't build their own nest. They lay eggs on other bird's nest. Usually the young cuckoos are raised by another birds. And when they grow bigger, they push other young birds from the nest. So they symbolize selfishness and infidelity. Cuckoos are traditionally a herald of spring in northern Europe. They represent fertility. There is a word "cuckold". This represent a man whose wife is unfaithful. Some other ancient cultures consider cuckoos as a sacred creature. Some cultures believe that they posses magical powers.