Genes that control hair or feather color in some animals are expressed differently in the winter than in the summer. How might such a differently be beneficial to the ptarmigan shown here?

In the winter its color changes to more resemble their winter surroundings, so they are more white, enabling them to blend in better with their white surroundings. In summer, its color changes to more resemble its summer surroundings, so they are more brown like the rocks and ground around them.