Let's look at your sentence and make it easy to understand and grammatically correct:
Original sentence: Up in the mountains, a fluffy chinchilla basks in the sun, a chamois hops from rock to rock and a condor soars high above. Mallards flock to fly to warm countries.
Corrected sentence: Up in the mountains, a fluffy chinchilla basks in the sun, a chamois hops from rock to rock, and a condor soars high above. Mallards flock together to fly to warm countries.
Explanation:
- We added a comma before and to separate the list of animals doing different actions.
- We added together after flock to make it clearer that mallards are gathering before flying.
- The word countries is correct, but you can also say places if you prefer a simpler word for a 5-year-old.
This way, your sentence is clear and easy to understand!