I don't want to sound like a broken record here, but a lot of what is being discussed here could be resolved by adjusting the time-flow in the game to be slower so needs do not accumulate as fast and offspring don't spam the zoo into a population-control-micromanagement-game. Agree the reproduction rates to not need to change. This is all pretty much the same stuff that is discussed in the thread(s) about adjusting the time flow.