Where did all my birdies go?

I don't know if it's because the squirrels decided to bother everyone, or if there was some sort of predator I didn't see lurking about, but my birdies were absent at the feeders all afternoon.  I did see Mr. and Mrs. Cardinal closer to dusk when Lauren dropped me off after we visited the antique store, though.  They both stared at us as we drove up, and they didn't fly off when I opened the garage doors so we could pull through, which was great. 

There were a few assorted sparrows picking at the peanut suet, but other than that, I didn't really see anyone.  When it warms up, I'll be able to sit outside to watch the feeders regularly.  Until then, I'm forced to stare from the kitchen sink window as I walk up to it or past it.  I also put up the modified nuthatch house, which features a chickadee portal to make the hole smaller.  Following the directions, I also put some sawdust in so the birds can simulate "excavating" a nest.  I hung the nest from Ladybug Manor, which is a tree that is absolutely infested with ladybugs during the summer, due to the bugs that were attracted to the leaves.  I'm planning on making the tree unattractive to bugs by spraying a bit of sesame seed oil around if I see them this year.