What affects Zoo Upkeep Cost?

Solution 1:

Upkeep is determined as a fluctuating (random) cost that is dependent on a percentage of the cost of each building. The upkeep fluctuates with a simple noise function centered around 2-5% the buy cost of a building (depending on the type of building). Buildings that house animals have a higher upkeep as the cost of the animals ('asset cost') is added to the total net 'worth' of a building.

Because of this mechanic, it is not always cost effective to add animals without regard to attractiveness and/or skittishness, as sometimes additional animals can become a money sink rather than a way to generate revenue.

EDIT:

Here are some links to resources I linked to in the comments:

• Upkeep Stats
• Dino Happiness Stats
• Fences/Walls Stats