According to research, chili peppers are spicy because they contain a substance called "capsaicin", which can stimulate the "capsaicin receptors" in the mouths of animals. All mammals have this stuff, but birds do not.
If Chi Yuan is the spicy pepper that makes your nose run with tears and saliva, then Song Yaochen is the bird who is not afraid of spicy food.
In a word: Pepper's love.