Bird call, similar to this: https://www.amazon.com/dp/B0002E1MWO/ref=cm_sw_r_awdo_796MX6M7FHXT371A18XE
Reference books, log book, Binoculars?
bring one of these to school and you can get a closer look at the raptors as they mistake you for a large, slow meal
It sounds like one of those little bird call chirpers.
Probably would be super easy to sneak one of those into the stadium.