cathemerality , auch: metaturnality

Common brown lemurs (E. fulvus fulvus) have been observed seasonally shifting from diurnal activity to cathemerality.

Predation and cathemerality: Comparing the impact of predators on the activity patterns of lemurids and ceboids (subscription required).

Seasonal cathemerality has been described for the mongoose lemur (Eulemur mongoz) as activity shifting from being predominantly diurnal to being predominantly nocturnal over a yearly cycle.

Cathemerality and increased gregariousness might indicate that the larger living lemurs are evolving to fill the role of the giant lemurs, which were thought to be diurnal (day-living) and more monkey-like in behavior.

In the original manuscript for his paper, "Patterns of activity in the mayotte lemur, Lemur fulvus mayottensis," Ian Tattersall introduced the term "cathemerality" to describe a pattern of observed activity that was neither diurnal nor nocturnal.