Some animals, such as snowshoe hares, Arctic foxes, and ptarmigans, have the ability to change their coat color with the seasons. This adaptation helps these animals blend into their surroundings as the environment transforms. During winter, their fur or feathers turn white, providing camouflage against snowy landscapes. In summer, they turn brown or gray to match soil and vegetation. Unlike plants, which change color in response to temperature and light variations that affect pigments like chlorophyll, animals rely on biological triggers such as day length. These triggers initiate hormonal changes that regulate coat color and texture transitions.
The mechanism behind seasonal coat color change is deeply rooted in evolution. Over millennia, many species developed the ability to use day length—or photoperiod—as a reliable signal to anticipate seasonal changes. Seasonal changes in the length of the photoperiod (hours of daylight) influence hormone production in the animal's brain. The brain then stimulates the body to produce different pigment levels in new fur/feather growth, resulting in a color shift depending on the season.
Climate change, however, is disrupting these carefully timed adaptations. Warmer temperatures and changing precipitation patterns are delaying snowfall and shortening periods of winter conditions, causing mismatches between the environment and the timing of coat color changes. For instance, animals relying on day length to guide their seasonal shifts may turn white before snow covers the ground, leaving them more vulnerable and exposed to predators.
