I was thinking of doing something similar when I was brainstorming. Glad to see someone actually made a game where it's about a larger scale running out of control.
Played it until I had around 600 points, because I the feeling due to the often accruing events and the cars most things were actually quite good under control (about equal 40-50 animals).
One time I was at 100 bunnies.
What is the losing condition?