I read your article about wrens and would like to add that our Carolina Wrens that frequent our back yard love safflower seeds (which can be found at any good bird food supply place) and raw unsalted sunflower seeds that I grind into small pieces in my magic bullet.

The problem is wrens breaks are not great seed crackers, so the shelled sunflower seeds a perfect for them.

I put them on our window sill and I have seen four different wrens as well as a winter wren scarf them down.