When the sun is down and daytime animals, known as diurnal animals, are resting for the night, a new group of animals starts their day. These animals are nocturnal meaning they are active at night. It can be easy for us to overlook them when we are asleep.
Many physical characteristics make nocturnal animals interesting. Nocturnal animals evolved special adaptations to get around at night, including:
- Eyesight: Nocturnal animals, like flying squirrels, have large eyes and their pupils expand more widely so their eyes can capture more light. By having good night vision, they are less reliant on needing colour vision to see.
- Hearing: Nocturnal animals often have larger ears. Many have cupped-shaped ears to allow more sound in. Some species of owls have asymmetrical ear openings, where one ear opening is higher than the other. This allows them to pick up on small differences in the direction that the sound is coming from.
- Touch: Many nocturnal animals have a heightened sense of touch so they can feel around in the dark. For example, raccoons have more sensory receptors in their paws to differentiate objects based on how they feel.
- Echolocation: Bats send out sound waves that bounce off objects and travel back to them. This allows them to “see” at night. They can tell the distance and size of nearby objects such as trees and their dinner – mosquitoes and other insects.
There many advantages to being active at night, including:
- Less competition for food: Many animals have the same food sources. To overcome this, animals that are active at night can take advantage of the same food sources during “off” hours. For example, hawks and owls both feed on small rodents. Since most owls are nocturnal, it reduces competition and increases their chance of finding a meal.
- Less likely to be seen: This is an advantage for both predators and prey. Predators can more easily sneak up on their unsuspecting prey and prey use the cover of darkness to move about and feed.
- Fewer predators: There are less predators at night since animals need special adaptations to see in the dark. Therefore, it’s safer for prey to be active.
Threats to nocturnal animals
Light pollution is one of the primary threats to nocturnal animals. As human populations expand, our nighttime skies have become brighter. Light can:
- Disorient animals: Nocturnal migrating birds rely on the stars and moon to navigate.
- Attract animals: Light also attracts animals, like moths, to areas where they may be an easy target for predators.
- Push animals away: Light pollution pushes nocturnal animals to darker areas, further from areas that they would have otherwise used.
How you can help
The good news is there are a few ways you can help nocturnal animals. The first, is to turn off lights when they are not in use. This easy solution also has the benefit of saving your energy and money. The second, is to become a citizen scientist and submit photos of nocturnal animals to online citizen science platforms like iNaturalist. These records can be used by researchers to study them.
Learn more about wildlife in the Credit River Watershed.
By Christina Kovacs, Natural Heritage Management