What is "cathemerality"

Cathemerality, sometimes called metaturnality, is the behaviour in which an organism has sporadic and random intervals of activity during the day or night in which food is acquired, socializing with other organisms occurs, and any other activities necessary for livelihood are performed. It has been defined as follows: "The activity of an organism may be regarded as cathemeral when it is distributed approximately evenly throughout the 24 h of the daily cycle, or when significant amounts of activity, particularly feeding and/or traveling, occur within both the light and dark portions of that cycle."

Many animals do not fit the traditional definitions of being strictly nocturnal, diurnal, or crepuscular, often by factors that include the availability of food, predation pressure, and variable ambient temperature. As a result, many species, particularly among primates, may be classified as cathemeral.

Alternative patterns of cathemeral activity have been observed in specific lemurs. Seasonal cathemerality has been described for the mongoose lemur (Eulemur mongoz) as activity that shifts from being predominantly diurnal to being predominantly nocturnal over a yearly cycle. The Common brown lemurs (E. fulvus fulvus) have been observed as seasonally shifting from diurnal activity to cathemerality.