Welcome to the forum! Glad you joined us! Look at it from another angle. If the hens can clean up a treat in 10 to 20 minutes, you are very safe. It's not going to be a huge part of their diet that way.
One way to stop wild birds from getting to your feed is to keep you chickens totally enclosed in a run with wiring that the wild birds canlt get through. Some people feed inside the coop instead of in the run to try to stop the wild birds from getting as much. I still regularly find wild birds in my coop, but it does seem to reduce the amount they eat.
