It seems like you will need to pre-process this since the climate for the enclosure isn't based on our local position. Maybe you can use a tool like Elements or Climate Consultant on an EPW of the representative location, or open renamed EPW as CSV in Excel. There are a number of websites that can give you sunrise and sunset time, and additional data beyond that.
However you come up with the pre-processed schedule, if it is relatively complex vs. just changing once a month, then you may want to consider using a schedule file object (If you are using EnergyPlus) which allows you to describe your schedule in an external CSV file that is used by EnergyPlus at runtime.
It's also possible the zoo staff already have this information, and you could get it from them. Something to keep in mind, The zoo may shift the timing of this for example to have nocturnal animals up in the day instead of the night? That wouldn't impact your lighting consumption total but would impact the timing of it. I wouldn't think this would be a big driver of your project, if you put in default lighting schedule having it on when zoo is open, the resulting lighting will probably be lower than that.