I purchased 2 isa brown hens 2 weeks ago. They are currently 18weeks old as advised by the pet store keeper. I let them out free ranging an hour before sunset. They are friendly, timid, curious while I'm walking around the garden, inspect each corner and run away if I try to pat them. Last week they would walk themselves to bed when the sun sets. But the past few days one has started to get aggressive 10 minutes before bedtime, run towards humans standing around, threaten to jump and has jumped and fly kicked by father's back. We have stood our ground and held it down for a minute to calm it down. This is starting to become a regular daily bedtime crazy snap this week. Why is this happening and how do I stop this bedtime behavior?