Initially when I saw the mess left underneath the feeder I blamed the squirrel.
A few snowfalls later though and not only was the feeder empty (there seemed little point in filing it since I was back to work and not able to do any viewing) but the seed that had fallen on the deck was now buried under several inches of snow. This afternoon, I took a shovel and excavated a small pit so my avian visitors wouldn't have to dig to China for a meal. I also re-filled my feeder of course. I went back inside hoping I could get a few days of viewing before the resident squirrel came and made another mess.
A couple hours later, though I happened to pass by the kitchen window and noticed some of the ubiquitous red polls at the feeder.
Turns out they were only doing what birds do. They are rather messy eaters. My feeder has some small perches on the side but lacks a tray so as little avian appetites were sated, a mess slowly gathered on the ground. As it happens the fault lies with me.