Answer:
The theme is friendship.
Explanation:
The following has NOT been plagiarized. The following is using my OWN words:
The theme of Duck and the Kangaroo is friendship. It shows that friends who help others also feel happiness for themselves [because they helped and were kind to others]. Like the title, this story is based off of two characters, the Kangaroo and the Duck. This story tells tales of their adventures, as well as their speech [dialogue] to one another.
I hope this helps!