ExtendedRaceProperties - Vanilla-Expanded/VanillaExpandedFramework GitHub Wiki
ExtendedRaceProperties makes animals Diurnal (default), Nocturnal or Crepuscular.
        public BodyClock bodyClock; //(values can be Diurnal (default), Nocturnal or Crepuscular Diurnal animals (default ingame): active from 7 AM to 21 PM
Nocturnal animals: active from 19 PM to 9 AM
Crepuscular animals: active from 3 AM to 16 PM
As an example, this patch makes the Nightram in Alpha Animals nocturnal
    <Operation Class="PatchOperationAddModExtension">
        <xpath>/Defs/ThingDef[defName="AA_NightRam"]</xpath>
        <value>
            <li Class="VEF.AnimalBehaviours.ExtendedRaceProperties">
                <bodyClock>Nocturnal</bodyClock>
            </li>
        </value>
    </Operation>