Animal Timing - Biological Clock

Exogenous

A direct response to the environment cues that aren’ internally controlled

Endogenous

Controlled by the internal biological clock that continues in absence of environmental cues, but the period may change slightly from what happens in natural environment

Zeitgeber

“Time Giver” The environmental cues that resets biological clock so that it’s synchronised with environment, acting as a time keeper

Entrainment

When the internal clock is reset to take up the (new) period

Period

Length of one complete cycle of a rhythm

Free running period

Behavioural pattern that continues despite the removal of external cues (zeitgeber)