We usually spend about 1-1.5 hrs. That is without a visit to the gift shop or rides on the train.
About 2-2.5 hrs
1.5 hrs minimum.
It took us 3 hours
It's not a big zoo, but it's a nice one. I'd say 2-3 hours should be enough, longer if you want to eat snacks, visit their gift shop, etc. If you come first thing in the morning, especially during the summer when it's still cool before noon, you should be comfortably done at noon or 1 pm or so.
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