Why do some animals in the taiga experience a seasonal color change?

The winters are long and cold and the summers are short and cool in the taiga biome. About 29 percent of the forests in the world are formed of the Taiga biome, situated in both Eurasia and North America. These forests make good habitats for various distinct kinds of plants and animals. Despite the harsh environments, various animals are found in the biome, as they possess unique characteristics, which assists in protecting them from the harsh surroundings.  

Some of the animals found in taiga biome are moose, wolverine, bears, foxes, and birds. The majority of the animals found in the taiga biome are the animals, which feed on other animals in order to survive. Due to this, several of these animals possess the tendency to modify their color that permits them to camouflage themselves from threat.  

The animals in the biome experience a seasonal change in color as in order for camouflage to be effective in the taiga biome, it must account for both winter and summer conditions. In the winter, the appearance of white fur is an efficient camouflage, and in the summer it is not.  

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a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.