Animals Wildlife What Is a Crepuscular Animal? Animals like rabbits, house cats and deer are neither nocturnal nor diurnal. Instead, they're crepuscular. By Jaymi Heimbuch Jaymi Heimbuch Writer California Polytechnic State University, San Luis Obispo Jaymi Heimbuch is a writer and photographer specializing in wildlife conservation, technology, and food. She is the author of "The Ethiopian Wolf: Hope at the Edge of Extinction." Learn about our editorial process Updated February 2, 2022 DamianKuzdak / Getty Images Animals Wildlife Pets Animal Rights Endangered Species Most of us are familiar with two of the terms for periods of activity in plants and animals: nocturnal and diurnal. Nocturnal animals like bats are active at night and diurnal animals like humans are active during the day. But there’s another major category for the activity for animals and that’s crepuscular. Crepuscular—a word drawn from the Latin word for “twilight”—is a term for animals that are active primarily at dawn and dusk. There’s a very smart reason for picking these dimly lit in-between hours to be active: crepuscular critters are avoiding predators. According to SpringerLink: Crepuscular refers to twilight, the time shortly before sunrise and after sunset. In the context of animal ecology, it refers to those species active during these times of day. In other words, a crepuscular animal is one whose diel (24 h) activity pattern has peaks during the twilight hours (e.g., African wild dogs). Crepuscular can also be used to refer to specific behaviors of non-crepuscular species that usually occur during twilight (e.g., nocturnal smooth-tailed newts are crepuscular breeders). The Benefits of Being Crepuscular Many predators are most active at the peak hours of daylight and darkness, so animals like rabbits which are a prey species for countless carnivores, are active during twilight hours when predators are already tired from a night of hunting or are just waking up. Plus, it’s tough to see during these hours, a fact that gives prey species an added edge in hiding from or escaping predators. In hot areas, there’s another reason for crepuscular activity: It allows animals to be active when the temperature is most reasonable. Desert animals can escape the heat of midday and the chill of midnight by being active at dawn and dusk instead. Some species may shift from being nocturnal or diurnal to being crepuscular due to environmental factors such as competition with other species. For example, some owl species may be crepuscular to avoid competition with other raptor species—or disturbance from human activity. Crepuscular activity is further broken down into matutinal animals, which are most active in the morning, and vespertine animals, which are most active at dusk. The domestic house cat is a great example of a crepuscular animal, as are rabbits, deer, some bat species, bears, skunks, bobcats, possums, and many, many more species.