Find the punctuation mistakes giving comments.

a lot of birds and animals move from country to country and from continent to continent during the year some move when summer is over and it becomes colder and colder and some when there is no food to eat many birds can't find food under the snow so they fly to africa and other warmer countries. when winter comes some birds can fly more than 7000 km in 3 days when spring comes they return and never see winter