I dunno. If we assume rational, greedy owners and the costs are fixed(as in, there's a cost per animal, not a cost per visitor), the costs are pretty much irrelevant to pricing. They'll want to maximise income. The parameters that matters are how many visitors you'll get at any given price point, multiplied by that price point.

Ofc, I'm assuming Homo Economicus run this zoo, that might not be accurate irl