I grow burdock (borre) in the garden both as a vegetable but also for the birds. Goldfinches / stillits (still relatively rare in my area) eat almost exclusively the seeds of this plant in winter. This year I cut down a few of the plants and placed them in a large pot of earth right in front of the kitchen window…and 4 birds discovered it today. How they avoid the burrs attaching to them is a mystery….
Some of the seed burrs had fallen to the ground in a storm a week ago. This video starts with siskins feeding next to the window on birch seeds: