Cardinals and variable habitat choice

Today I took both dogs for a walk (at the same time, that was interesting), and I checked out a path leading to the railroad tracks that I haven't used in several years. The surrounding vegetation is mostly tall meadow grasses (though it's only a narrow corridor between two parking lots) and scrubby shrubs (mostly sumac). Anyways, as I was walking along I flushed out several cardinals which were hanging out in this area. It made me realize that I hadn't seen many, if any, cardinals this fall in my neighborhood. They're usually pretty common, and especially easy to see once the leaves have fallen off the trees (they also tend to call even in the fall, drawing attention to themselves). I even pass right by a house with several bird feeders every morning when I walk Angel. It's usually swarming with birds, though they're mostly house sparrows (I see finches there too sometimes). I'm fairly certain that I used to see cardinals pretty frequently at these feeders.

I wonder why the cardinals haven't really been around in the neighborhood? Has there been a population crash? Are fewer people stocking their bird feeders because of the recession? Are people stocking different seed types (I believe cardinals prefer black oil sunflower seeds)? And I wonder if cardinals tend to hang out by the railroad tracks even when they're prevalent in the surrounding neighborhood?

Obviously I don't have the answers to those questions, and I guess I haven't even been terribly observant about it in the past so I can't really be sure of how great the difference is. It really makes me want to live somewhere more rural (or closer to the park), and to put feeders out so that I could actually observe birds every day (more than just the local house sparrows and starlings). Oh, how easy it was when I was in the Smokies...