The reason why birds sing more in spring is not accidental, but has a biological explanation.
In 2012, scientists at the University of Oxford (United Kingdom) identified a gene in birds that produces a light-sensitive molecule in the hypothalamus, a region of the brain linked to the regulation of hunger, sleep and sexual desire. In spring, this molecule detects that the time has come to look for a mate and activates the reproductive system of birds.
“When we hear birds singing in spring, it is because a molecule sensitive to light in their brain has been activated, ” says Russell Foster, co-author of the work. By matching mating to the change of season, “the birds ensure that there will be more food available for their young when they hatch,” adds the researcher.
The identified molecule belongs to a family of photopigments called opsins , which detect changes in ambient light, such as those that occur during dawn and dusk . Researchers have also found these opsins in amphibians, reptiles, and other birds, but not in mammals.
However, mammals are also seasonal animals, including humans. Specifically, changes in light in the seasons have been shown to alter the production of melatonin . For example, in sheep, when autumn arrives and days are shortened, the increased production of melatonin stimulates reproduction, increasing the number of sperm in the semen of the males while increasing the fertility of the females. . This mechanism allows the lambs to be born coinciding with the arrival of spring.
