Theory:

     “You are right, Sir,” answered the bird. “He is my brother but he has made friends with robbers. He now talks as they do. He doesn’t talk to me any more.” Just then the rishi entered the ashram.
Explanation:
 
The bird told the king that he was ever right. The bird was his brother, but he had been looked after by robbers. He too, had become like them. The bird added that he and his brother no longer speak to each other. Just then, the rishi entered the ashram.
 
Meanings of difficult words:
  
Numbers
Word
Meanings
1.
RobbersThieves.
2.
Entered Set foot in.
Reference:
National Council of Educational Research and Training (2006). A Tale of Two Birds (pp. 01-03). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.