Haha. There actually has been some questioning about the potential of the birds realizing it is a fake and possibly creating a new call. The experiments are usually kept pretty short both to help prevent discovery and to protect the robo-raptor. Some bird are very territorially, especially when nesting, and there have been cases of other birds banding together to attack the robots to try and scare them away. This of course, can end the experiment prematurely. Here is a video with a the lead researcher on the project and a different owl and towards the end you can see a bunch of other birds flying in to intimidate a robo-owl. The video also shows a little bit more of the set-up than I have included in my article. There is actually a video of birds attacking the robo-raptor as well, but I can not seem to locate it right now.