Radio stations....

I live in a small town in the NW, and there is a large, wooded park behind our house.
I have a bear that regularly comes thru and destroys my bird feeder.
I put up a motion detector light - with two sockets. I put a spotlight bulb in one and a screw-in plug adaptor in the other. Plugged an old-fashioned radio in the adaptor and set it up to come on for about 30 seconds if motion was detected at night.
Works like a charm.
Only problem is... the loudest, most obnoxious station I can find is RW screamers. Two different stations. The rock stations drift off frequency, and the pop stations' music/talk is too subdued.
Why is it that the best radio reception is from the worst stations? Are they over-powered or something?