An experiment to see if small birds prefer shelled or unshelled black oil sunflower seeds is tipping toward the sans-shell variety. I read recently that small birds, chickadees in particular, would favor shelled seeds because no shell means no energy expenditure in hacking shells open. Every little bit of energy counts, particularly in winter.

The feeders, two identical, hanging two feet apart above our deck, have been in place for about 10 days. That probably isn’t adequate for a conclusion. There is a difference for chickadees, though. They’re caching seeds for winter right now, shelled seeds their choice.

The feeders are new, both with a fine gravity-driven anti-squirrel mechanism. Put the weight of a squirrel on the feeder perches and a cage slides down to cover the feeder ports in the plastic seed-holding tube. These Squirrel Buster Classic feeders, manufactured by Brome Bird Care up in Ontario, have a cage of heavy wire strands set close enough together to prevent squirrel gnawing. The tops remove easily with a simple twist for convenient filling. This is a feeder intelligently designed.

A previous feeder of basically similar design was a total failure. In this case the square cage purportedly protected three tubes holding seed. The cage wires, however, were set so far apart that squirrels could easily gnaw free the feeder ports, allowing seed to pour out. Decorative flowers punched from flimsy sheet metal were placed to cover feeder ports when the feeder was protective mode. The squirrels could bend those out of position with their teeth. They were able to do so because they learned to hang from the feeder top with their toes, circumventing the gravity feature. It was very irritating to watch. (The new feeder does not accommodate that.) I duct-taped the first two gnawed wounds, then said to hell with it, and bought the new ones.

I paid about $20 for the bad feeder, pleasantly surprised at the price until I put it to use. The new ones cost $54 each, but should last the lifetime of the springs or until gravity quits. They could become heirlooms. Below, one of the new feeders.