Until they can't anymore because something happens and they realize they need each other's help.
The story is told in simple terms with certain exceptions. It relies a lot on the reader or listener to understand the passage of time and just how long years are in order to really be funny. Kids young enough to enjoy the book would have a hard time with that.
The images also lack vibrancy. I wish there'd been more color to keep a kid entranced.
But it's short enough that they won't get bored before the end. Stories about animals are always a hit and this one is no different.
A cute story of what it takes to become friends, told in an engaging style that's sure to entertain little ones.