typically during bouts of hunting. they have to hunt regularly not only for food, but to gather mana, which they get through drinking the blood of magical creatures. the more powerful the magic of the creature, the more mana they can gain. they will need to shift more frequently during hunting periods, not only to aid in capturing prey, but as a necessary compulsion that coincides with the hormonal state

mana is required for a shapeshifter to shift, so while during hunting periods they exert a lot of mana, they are typically able to stock up on plenty during the hunt to make up for it