Strangely, I've noticed that as the temperature has dropped and autumn, then the start of winter have encroached, there have been fewer birds on the feeders in our gardens. These offer a variety of seeds and fat balls, but right now I'm seeing very little patronage at all, just when I'd expect birds to start relying on feeders for their sustenance. I wonder why this is?

Maybe it's just an oddity with my garden (and not statistically significant), maybe they're put off by the lack of foliage on nearby trees so they can't creep up to the feeders to easily. Maybe there's actually a great natural source of food right now that I'm unaware of, even though it's cold.

Update: one possible reason becomes clear.