Many animals undergo seasonal changes in their appearance as an adaptation to their environment. These changes typically serve three main purposes:
- Camouflage – Arctic foxes and snowshoe hares turn white in winter
- Temperature regulation – Growing thicker fur or feathers
- Breeding displays – Brighter colors during mating season
These changes are typically triggered by hormonal responses to changing day length (photoperiod). For example, many birds molt their feathers seasonally, replacing dull winter plumage with brighter breeding colors in spring. Some mammals, like ermines and arctic hares, produce different pigments in their fur based on seasonal cues.