The term used for animals that are mainly active at dawn and dusk is "crepuscular." These animals have adapted to be most active during the cooler parts of the day—at sunrise and sunset—when they can take advantage of lower temperatures and reduced risk from predators. Examples of crepuscular animals include deer, rabbits, and some species of birds. This behavior helps them conserve energy, find food, and avoid the extremes of heat or cold that occur during midday and nighttime, respectively.