On the one hand, it should not press, rub, in a word, interfere with the bird, and on the other, it should not be too loose and let light through the cracks. The hidden seam that connects the shreds is of ancient origin. There are no strings on it that the bird would inevitably tear. The knot with which the entanglements (straps) on the paws are tied is also special: the bird itself cannot untie it with its beak.
Photo: Natalia Remmer