The zoo was historically part of the park. fenced off.

There's also some other historic quirks, such as several closed gates between into the zoo from the park and the Bison exhibit being designed to be visible from the park outside of the zoo.

The phrasing in https://en.wikipedia.org/wiki/Buffalo_Zoo places the Zoo in the park. I'm going to go with that and move the park's area to overlap with the Zoo.