Nice. – Good then. Here, I have another question from an eleven-year-old boy, who occupies himself with ornithology and, thus, with the study of birds. He asked me about how the birds know what they can eat. With this, he means, what is edible for them and what is inedible, respectively toxic, for them or how the birds know, in particular, what berries to eat, whether the fruits would be ripe and good for them.
33. That is no secret.
34. Mature fruits and berries store and reflect solar radiation, and when these are ripe, they emit light in the ultraviolet range, even when the Sun isn’t shining.
35. This shortwave light is perceived by the birds, as well as by certain animals and insects, and it is the signal that the fruits or berries are ripe for digestion.
36. This equally applies to the edibility of fruits and berries, grasses and leaves, etc., which emit a certain radiation that is perceived by the organisms and that informs them that the food which is important for them is nontoxic.