Theory:

     ‘Mom!’ Payal cried, ‘You’ve killed her!’ Payal’s mother was equally aghast. ‘Oh!’ she said. ‘Oh, what have I done? The poor, little bird!’ After Payal and her mother had finished crying and hugging each other, they started talking bravely about where to bury Owlie. Just then, Owlie opened one eye and then the other. She got onto her feet and quietly climbed the perch!
 
     Payal learnt later that falling on her back and pretending to be dead was Owlie’s way of defending herself against danger. Not that Payal’s mother was a danger to Owlie, but the baby owl did not know that then. So that was Owlie’s first day at home.
Explanation:
 
Payal was shocked when Owlie fell down. She screamed "Mom" and said that she had killed Owlie. Payal's mother was also equally horrified. She wondered what she had done to the poor little bird. Payal and her mother hugged each other and started crying and expressed their grief over Owlie's death. Then they started discussing about where to bury the owl. At the same time, Owlie opened one eye first, then the other! Quietly she got up and climbed the perch.
 
Later, Payal understood that falling down and acting to be dead was Owlie's way of protecting herself from enemies or danger. Payal and her mother were not dangers to Owlie, but Owlie was a baby owl who did not know that. These incidents happened on the first day when Owlie got home; Owlie needed time to understand whether they were dangerous or not.
 
Meanings of difficult words:
 
Words
Meanings
aghastshocked, horrified
pretendact/pose
Reference:
State Council of Educational Research and Training (2019). Term-1 English Standard-6. Owlie - Vijaya Ghose(pp. 101-104). Published by the Tamil Nadu Textbook and Educational Services Corporation.