Nature at night: nightlife in the wild

Francis Skalicky, Missouri Department of Conservation
The great horned owl is one of the nocturnal creatures that can be seen at night.

For centuries, nature’s nocturnal world has been a source of both fear and fascination for humans.

Owl hoots, coyote howls, and other wildlife sounds of the night were once considered omens of bad health, bad luck and other misfortunes that would befall the human who heard these calls. Today, thanks to a better understanding of the animals that are active at night, uneasiness has been replaced with interest and appreciation of these creatures. Nature at night is a world full of fascinating adaptations and interesting characteristics.

Before getting to a description of those, let’s answer the over-riding question: Why are these creatures active at night? Interestingly enough, some of the answers have benefits for both prey and predator.

One advantage to nocturnal activity is the obvious one – it’s harder to be seen in the dark. For animals with few natural defense mechanisms, being active at a time when it’s hard to be seen is a key to survival. However, this advantage cuts both ways – being hard to be seen because it’s dark is an advantage for predators, too, because it’s easier to sneak up on prey.

Another benefit for nocturnal animals is that there are fewer predators at night, thus it’s a safer time to find food, water and all the other things needed to live. However, this is also an advantage for owls, bobcats, and other animals that hunt at night: Because there are fewer predators, there’s less competition for food items.

Although it’s not applicable at this time of year, another benefit of a nocturnal lifestyle in warmer months is that, because nights are cooler, being active at night avoids over-heating, becoming dehydrated and is simply a better way to economize bodily energy.

Surviving at night requires several interesting adaptations. One is eye size. If you look at nocturnal creatures such as flying squirrels and owls, one thing noticeable is they have large eyes. In some owls, for instance, their eyes make up three to five percent of their body weight (for comparison, eyes constitute .0003 percent of a human’s body weight). These large eyes help to gather what little light there is and, thus, help animals see better in the dark.

Another interesting eye feature that owls, whip-poor-wills, felines (including domestic cats) and some other animals active at night have is a tapetum lucidum. This is a membrane at the back of each eye that acts like a mirror and reflects light back through the retina. Without getting into a lot of optical science, basically what this does is to give creatures greater ability to see things in low-light conditions.

Nocturnal predators have several interesting physical characteristics that add to their night-time hunting effectiveness. In addition to their large eyes, owls have serrations along the edge of their flight feathers, which greatly reduce the sound of air flowing over the wings.

Bats use echolocation to navigate and hunt in total darkness. Bats emit pulses of high-frequency sound and, by processing the echoes reflected back to them, can locate objects near them. This allows them to avoid buildings, tree branches, and other things which may be in their flight paths and at the same time, helps them locate insects to catch and eat.

Although many people aren’t fans of venomous snakes, they also use a truly fascinating feature to hunt at night. All of Missouri’s venomous snakes are pit vipers, which means they have a heat-sensitive pit between the nostril and eye on each side of their head. These pits help the snake detect warm-blooded prey. Even in total darkness, these pits help the snake locate and identify a small mammal or other type of prey within approximately a two-foot radius. Basically, it’s a wildlife version of thermal imaging.

Venomous snakes and bats are not active at night at this time of year, but people can find out more about nocturnal animals that are out and about during winter at the Missouri Department of Conservation’s (MDC) “Discover Nature: Nocturnal Animals Virtual Program” from 1-1:30 p.m. on Saturday, Feb. 27. During this free online event, which is recommended for all ages, MDC Naturalist Morgan Wyatt will discuss Missouri’s nocturnal creatures and the adaptations they use to survive in the dark. People can register for this program at: https://mdc-event-web.s3licensing.com/Event/EventDetails/175733

People can also learn about wildlife that’s active in the state – both at night and during the day – at mdc.mo.gov.

Francis Skalicky is the media specialist for the Missouri Department of Conservation’s Southwest Region. For more information about conservation issues, call 417-895-6880.