Some examples of diurnal animals are humans, birds, pet dogs and cats, squirrels, elephants, gorillas, hawks, butterflies and honeybees. All of these animals are considered diurnal because they are mainly active during the day and asleep at night.
Scientists generally agree that diurnality is a product of evolution. The process of evolution has allowed for animals to take advantage of all possible niches; therefore, some animals are adapted either for daytime activity, night time activity, or dusk and dawn activity. That way, environmental resources are in use at all times without extreme competition for food or shelter. Diurnality is thought to be dictated by circadian rhythms, which are 24-hour cycles of physical, mental and behavioral patterns that respond to light and darkness in an environment.
Some animals, such as domesticated dogs and cats, have changed from their natural night time, or nocturnal, cycles to match human life. Others, such as beavers, are naturally diurnal but became nocturnal in order to avoid excessive predation during the day.
Diurnal animals have different adaptations for their environment. The daytime tends to be brighter, warmer and drier; night time is darker, cooler and more humid. Therefore, diurnal animals usually have different physical features, such as smaller eyeballs, since their eyes do not need to capture as much light as animals that navigate at night.