Theory:

     A few weeks passed and the animals of the forest looked tired and fed up. The RATS! Now that there were no snakes to eat them, the rats had taken over the forest. And they were having a wonderful time. They were everywhere, on the trees, in the grass, in the bushes, on the ground. They ate up the eggs of the lizards and crocodiles. There would be no babies that year. Makara’s own nest of eggs had been chewed up.
 
     Then Makara had a great idea. He called a meeting of the crocodiles and said, “Wouldn’t it be wonderful if we, the crocodiles, could have the WHOLE jungle for ourselves? No one but us? These lizards, now, just look at them! They have the strangest habits, and some of them even change colour! How can we trust someone who is green one minute, red the next? Let’s get rid of them.”
 
     By now, the crocodiles were really scared of Makara. So they clapped and cheered. Makara was pleased. The lizards left the forest, some with their babies on their backs.
Explanation:
 
As expected, there arises another problem in the jungle with the expulsion of snakes. Rats, in the absence of snakes to swallow them, took control over the whole forest. They really enjoyed having fun inside the forest without snakes.

When there is an expectancy of a wonderful life to be met in the forest without tortoises and snakes, it happened to be the other way around, as, 'Rats' began to create more trouble to the whole forest, filling up each place like, trees, grass, bushes, ground, etc.
 
rats in the forest draft.jpg
Rats everywhere
 
They did not spare even the eggs of lizards and crocodileseven Makara's own nest is eaten up; and, there were no eggs around that year. Makara expressed its wish for its fellow mates of occupying the whole forest for themselves (Crocodiles).
 
jungle with crocodiles draft.png
Jungle with only crocodiles
 
With this, Makara also announces its decision of expelling lizards this time from the forest. The reason given behind chasing them from the forest is their colour changing nature. On hearing this, the other crocodiles applauded Makara being filled with fear. At last, the Lizards were also forced to leave the jungle, carrying their babies on their backs.
 
lizard draft.jpg
Lizards left the jungle
Reference:
National Council of Educational Research and Training (2006). What Happened to the Reptiles - Zai Whitaker (pp. 33-42). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.