Caribou have adapted a life cycle that favors nutrient and energy conservation in the winter months and rapid growth and energy/nutrient storage in summer months. Preferred forage species are highly dependent on season. Nutrient and digestible energy content in plants is linked to growth stage. Seasonal forage preferences of caribou correlate to the plants species, plant parts, and growth stage that contain the highest available nutrients and energy at the time. Vegetation communities preferred by caribou are thus seasonally dependent.