The amount of ownership you have over your work really depends on the park and data you are working with. My supervisor gave me a problem and basically gave me autonomy over how to solve it using GIS. He gave me some indication about what kind of end result he wanted, but otherwise I was free to collect the data that I thought that I needed and figure out the best ways to present the results. This might be different if your supervisor has more knowledge about GIS and is planning to work more closely with you on the project. As for continued ownership past the end of the internship, I was allowed to keep the maps and data that did not disclose sensitive data about the park so that I could show others what I accomplished over the course of my internship. Again, this policy may vary according to your specific project as well as the park you work with.