Cathemerality

[2] Many animals do not fit the traditional definitions of being strictly nocturnal, diurnal, or crepuscular, often driven by factors that include the availability of food, predation pressure, and variable ambient temperature.

[3] Although cathemerality is not as widely observed in individual species as diurnality or nocturnality, this activity pattern is seen across the mammal taxa, such as in lions, coyotes, and lemurs.

Such factors include resource variation, food quality, photoperiodism, nocturnal luminosity, temperature, predator avoidance, and energetic constraints.

In other words, an animal's activity distribution may be somewhat dependent on the presence of the lunar disc and the fraction of illuminated moon in relation to sunset and sunrise times.

[11] For example, to reduce heat stress, eastern grey kangaroos (Macropus giganteus) will spend hot daylight hours in the shade and as a result, they increase their nocturnal activity.

This provides an advantage to cathemeral animals as their predators are unable to anticipate the activity pattern of their prey due to their irregular, flexible schedule.

[14] In contrast, small body size causes increased metabolic rate which may also result in cathemeral activity as an attempt to improve foraging efficacy, as seen in shrews and voles.

[15] The evolutionary disequilibrium hypothesis suggests that cathemerality is a result of the diversification of more specialized activity patterns, and somewhat viewed as a transition state between nocturnality and diurnality.