Answer:
I am a busy worker who is a water mammal.
I go from house to house a messenger small and tight. Whether it rains or snows I sleep outside at night.
What is made of wood, but can't be sawed?
If a man carried my burden, he would break his back. I am not big but leave silver in my tracks. What am I?
I'm an animal. I love marching. I always wear a tuxedo. What am I?
When I'm born I fly. When I'm alive I lay. When I'm dead I run.