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Some backyard birds only show up every couple of years or so depending on their food sources in other places (they are called irruptive species). For example, Red-breasted Nuthatches eat conifer seeds in the forests of Canada. During years when those seeds are scarce, the birds will travel to the south to find food, and that’s often when I’ll see one or two visit my feeders throughout the winter.
I haven’t seen any irruptive species yet this season. One Red-breasted Nuthatch showed up in September, but he must’ve been just passing through. And usually by now we have Pine Siskins (photo above) or even a Common Redpoll or two, but I haven’t seen either of those species either. It must’ve been a good seed year in Canada.