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What Makes Nocturnal Animals Only Come Out at Night?

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The sleeping habits of animals can be fascinating, such as the question of why some animals are nocturnal. As with most animal behavior, it boils down to survival. Whether it's being able to find food or avoiding being another animal's next meal, nocturnal animals have plenty of good reasons to sleep during the day.


Animals such as hamsters are nocturnal because their predators are out during the day. While there are also predators at night, these small animals have a better chance of going unnoticed as they forage for food and water. During the day, they can rest safe and sound within their burrows and at night they can stealthily search for a bite to eat. If it were daytime, they would easily be spotted, especially by predators that live in trees or fly.


Some animals also come out at night because their prey comes out at night. For example, owls hunt for mice at night, who also happen to be nocturnal. Catching prey at night can be more difficult, but nocturnal predators are usually equipped with great hearing and eyesight, while some even use echolocation to hunt their prey. Bats are well-known for using echolocation to detect the hundreds of mosquitoes they eat each night.


Other animals are nocturnal because there is too much competition during the day. For example, mountain lions might hunt during the daylight, so coyotes hunt at night. This allows each species the chance to hunt for food without constantly fighting each other.


Some animals, such as some breeds of reptiles, need to sleep during the day to avoid the hot afternoon temperatures. For example, desert iguanas spend much of the daytime sleeping under trees and rocks, then they forage for plants and small insects at night. Another example is the chinchilla, which sleeps in the crevices of rocks during the day and comes out at night when the temperatures are cooler.