Other brands of Peanut butter are available

When I got back from Africa Oye on Saturday night, there was a smidgin of bird poo on the window shelf. Occasionally, young blue tits wander in through an open window, so I didn't think much of it. When I got back on Sunday night, there was significantly more poo. A mystery. All was revealed today. The female blackbird lands on the external shelf, checks where I am, then hops through the window for a beakful of  peanut butter. The male blackbird sits on a nearby branch and calls out a warning, as required. I don't mind them helping themselves, but I wish they knew the rule about not sh*****g on your own doorstep, or window shelf, in this case!