Father, Son & Pigeon

A father and his 5 years old son was strolling together in the garden, The son sees a Pigeon and asked his father "Is this Pigeon, Father ?", "Yes" replied father. "Is this Pigeon Father" Son asked again "Yes my son" Father replied. The son asked several times and father replied yes every time. After many years both were strolling in same the garden together. Now the father was an old man and son was a young man. Suddenly father sees a Pigeon and asked his son "is this Pigeon Son " "yes", Son replied. The father asked agin "is this Pigeon Son" "yes Father" Son replied angerily. The father asked again "is this Pigeon Son" This time son burst out in anger and shouted " are gone blind father, can't you see this is a Pigeon Why are you asking me again and again". Father was stunned and couldn't utter a word and looking at his son and The pigeon.