I have a large Bear den and had the same problem. I took the portion of 'The Jungle Book' from the front of the Bear handbook, edited it down a bit for length, and made it a responsive reading skit.
Basically, when I said "Shere-Khan", the boys led the audience in a tiger growl, etc.
I also grabbed coloring book-type pictures of the various animals mentioned (not the Disney version!) and had the boys color them and mount them on cards. Each held a different animal (some animals had more that one boys with a sign, but that's ok). When we got to that animal, they held up the sign, sort of like a for that sound.
We did this at the Blue and Gold and it was a big hit.
It had the added advantage of the boys not having to remember anything or get nervous on the big stage since I was the narrator.
If you want the actual edited version, send me a private message and I'll scan it for you.