What do the seasons of the year have to do with making a willow whistle?
Sap is a liquid that circulates within the sapwood of trees. Sap rises up from the roots. Sap contains water and minerals; in the spring it also contains sugars and stimulates the growth of the tree. A willow whistle requires the maker to remove the bark from a willow twig in a tube shaped piece. The best (or only) season that this can be done is in the spring when there is more sap rising up the tree. This makes the bark more removable from the twig.
