Well, a randomly-based model for the behaviour of bumble-bees was, indeed, devised, and is pretty consistent with their actual actions. The decision-making itself is based on threshold logic, but the actual actions are random.

Here's a link to Yael Niv's homepage (she presented this project at the Technion last year, as part of the Learning Club):
http://www.cns.tau.ac.il/~yaeln/

Actually, Heisenberg's Uncertainty Principle dictates a certain non-determinism in the Physical phenomena themselves.

Or so I've understood.