Why is the length of daylight hours the most important factor in seasonal changes in wildlife?

This is due to the fact that, due to the change in daylight length, the rhythm of the alternation of light and dark times of the day also changes. This phenomenon is called photoperiodism. Wildlife is very sensitive to it, adjusts and prepares in advance for seasonal changes. After all, living organisms will have, depending on the season, either to experience unfavorable factors, or, conversely, to increase the intensity of their vital activity.