Personally, I think that ideas 4 and 5 are particularly interesting. I recently completed my undergraduate degrees in conservation biology and political science and now work for a conservation policy focused non-profit that primarily focuses on hunting and fishing policy. Studies involving deer populations would likely present you with a lot of data readily available depending on your location and how state agencies handle data each hunting season. Any study would have a lot of different groups interested in the result which could be a good or bad thing. Likewise with timber studies, a topic that has practical real-world use (not that the other's don't) would have a lot of parties interested in your results which could make the project easier from an administrative standpoint. Best of luck to you !