Here's a breakdown:

* Photoperiodism: This is the biological response of organisms to changes in the length of day and night. It's a crucial factor in regulating seasonal behaviors.

* How it works: Plants and animals have internal biological clocks (circadian rhythms) that are synchronized with the environment, particularly the length of daylight. These clocks influence a variety of physiological and behavioral processes, including:

* Plants: Flowering, leaf shedding, dormancy, seed germination.

* Animals: Breeding, migration, hibernation, molting, fur growth.

Other factors that can influence seasonal behavior:

* Temperature: Seasonal changes in temperature can also play a role, especially for animals that hibernate or migrate.

* Food availability: Changes in food abundance can trigger seasonal behaviors like migration or hoarding.

* Hormonal changes: Hormonal changes within an organism are often triggered by photoperiod and can drive seasonal behaviors.

In summary: While temperature and other factors can play a role, photoperiod (changes in daylight hours) is the primary stimulus for most seasonal behaviors in plants and animals.